Fluid Mechanics Questions And Answers

Introduction to Fluid Mechanics 1. Which one is in a state of failure? a) Solid b) Liquid c) Gas d) Fluid View Answer Answer: d Explanation: A fluid is a Tresca material with zero cohesion. In simple words, fluid is in a state of failure. 2. A small shear force is applied on an element and then removed. If the element regains it’s original position, what kind of an element can it be? a) Solid b) Liquid c) Fluid d) Gaseous View Answer Answer: a Explanation: Fluids (liquids and gases) cannot resist even a small shear force and gets permanently deformed. Hence, the element must be a solid element. 3. In which type of matter, one won’t find a free surface? a) Solid b) Liquid c) Gas d) Fluid View Answer Answer: c Explanation: Solid molecules have a definite shape due to large inter-molecular forces. In liquids, molecules are free to move inside the whole mass but rarely escape from itself. Thus, liquids can form free surfaces under the effect of gravity. But, in case of gases, molecules tend to escape due to low forces of attraction. Thus, gases won’t form any free surface. 4. If a person studies about a fluid which is at rest, what will you call his domain of study? a) Fluid Mechanics b) Fluid Statics c) Fluid Kinematics d) Fluid Dynamics View Answer

Answer: b Explanation: Fluid Mechanics deals with the study of fluid at rest or in motion with or without the consideration of forces, Fluid Statics is the study of fluid at rest, Fluid Kinematics is the study of fluid in motion without consideration of forces and Fluid Dynamics is the study of fluid in motion considering the application forces. 5. The value of the compressibility of an ideal fluid is a) zero b) unity c) infinity d) more than that of a real fluid View Answer Answer: a Explanation: Ideal fluids are incompressible which means they will have zero compressibility. 6. The value of the Bulk Modulus of an ideal fluid is a) zero b) unity c) infinity d) less than that of a real fluid View Answer Answer: c Explanation: Bulk modulus k is the reciprocal of compressibility fi. k = 1⁄fi Ideal fluids are incompressible which means fi = 0. Thus, k will be infinity. 7. The value of the viscosity of an ideal fluid is a) zero b) unity c) infinity d) more than that of a real fluid View Answer Answer: a Explanation: Ideal fluids are non-viscous which means they will have zero viscosity. 8. The value of the surface tension of an ideal fluid is a) zero b) unity c) infinity d) more than that of a real fluid View Answer Answer: a Explanation: Ideal fluids haze zero surface tension but real fluids have some finite value of surface tension.

Fluid Properties 1. Which one of the following is the unit of mass density? a) kg / m3 b) kg / m2 c) kg /m d) kg =/ms View Answer Answer: a Explanation: Mass Density(p) is defined as the mass(m) per unit volume(V ), i.e., p = m ⁄v Thus, the unit of p is kg = m3. 2. The specific gravity of a liquid has a) the same unit as that of mass density b) the same unit as that of weight density c) the same unit as that of specific volume d) no unit View Answer Answer: d Explanation: The specific gravity of a liquid is the ratio of two similar quantities (densities) which makes it unitless. 3. The specific volume of a liquid is the reciprocal of a) weight density b) mass density c) specific weight d) specific volume View Answer Answer: b Explanation: Specific volume(v) is defined as the volume(V ) per unit mass(m). v = v⁄m = 1 / m⁄v = 1⁄p where p is the mass density. 4. Which one of the following is the unit of specific weight? a) N / m3 b) N / m2 c) N / m d) N / ms View Answer Answer: a Explanation: Specific weight(γ) is defined as the weight(w) per unit volume(V ), i.e., γ=w/v Thus, unit of is N = m3.

5. Which one of the following is the dimension of mass density? a) [M1 L-3 T0]. b) [M1 L3 T0]. c) [M0 L-3 T0]. d) [M0 L3 T0]. View Answer Answer: a Explanation: Mass Density(p) is defined as the mass(m) per unit volume(V ), i.e., [p] = [m]/[v] = [m] /[L3] = [ML-3]. 6. Which one of the following is the dimension of specific gravity of a liquid? a) [M1 L-3 T0]. b) [M1 L0 T0]. c) [M0 L-3 T0]. d) [M0 L0 T0]. View Answer Answer: d Explanation: The specific gravity of a liquid is the ratio of two similar quantities (densities) which makes it dimensionless. 7. Which one of the following is the dimension of specific volume of a liquid? a) [M1 L-3 T0]. b) [M-1 L3 T0]. c) [M-1 L-3 T0]. d) [M0 L3 T0]. View Answer Answer: b Explanation: Specific volume(v) is defined as the volume(V ) per unit mass(m). Thus, [v] = [V]/[m] = [L3]/[M] = [M-1L3]. 8. Which one of the following is the dimension of specific weight of a liquid? a) [ML-3 T -2]. b) [ML3 T-2]. c) [ML-2 T-2]. d) [ML2 T-2]. View Answer Answer: c Explanation: Specific weight(γ) is defined as the weight(w) per unit volume(V ), i.e.,

9. Two fluids 1 and 2 have mass densities of p1 and p2 respectively. If p1 > p2, which one of the following expressions will represent the relation between their specific volumes v1 and v2? a) v1 > v2 b) v1 < v2 c) v1 = v2 d) Cannot be determined due to insufficient information. View Answer Answer: b Explanation: Specific volume(v) is defined as the volume(V ) per unit mass(m). v = v⁄m = 1 / m⁄v = 1⁄p where p is the mass density. Thus, if p1 > p2, the relation between the specific volumes v1 and v2 will be represented by v1 < v2. 10. A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the liquid is found to be 6.5 N. The specific weight of the liquid will be a) 6:5 kN / m3 b) 6:6 kN / m3 c) 6:7 kN / m3 d) 6:8 kN / m3 View Answer Answer: a Explanation: Specific weight(γ) is defined as the weight(w) per unit volume(V ), i.e., γ = w⁄V Thus, γ = 6:5 ⁄10-3 N ⁄ m3 = 6:5 kN/m3. 11. A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the liquid is found to be 6.5 N. The specific gravity of the liquid will be a) 0.65 b) 0.66 c) 0.67 d) 0.68 View Answer Answer: b Explanation: Specific gravity(S) of a liquid is defined as the ratio of the density of the liquid(pl) to that of water(pw).

Thus, S = 0:66.

12. A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the liquid is found to be 6.5 N. The specific volume of the liquid will be a) 1 L /kg b) 1:5 L /kg c) 2 L /kg d) 2:5 L /kg View Answer Answer: b Explanation: Specific volume(v) is defined as the volume(V ) per unit mass(m). Thus,

13. Calculate the specific weight and weight of 20dm3 of petrol of specific gravity 0.6. a) 5886,117.2 b) 5886,234.2 c) 11772,117.2 d) None of the mentioned View Answer Answer: a Explanation: Specific weight = density*acceleration due to gravity =.6*1000*9.81=5886N/m3 Weight=volume*specific weight 14. If 200m3 of fluid has a weight of 1060N measured on the planet having acceleration due to gravity 6.625m/s2, what will be it’s specific volume? a) 0.8 b) 0.7 c) 0.9 d) 0.5 View Answer Answer: a Explanation: Specific weight=Weight/volume = (Mass*acceleration due to gravity)/volume =density*acceleration due to gravity =1/(specific volume *acceleration due to gravity) Specific volume=1060/(200*6.625). 15. For an incompressible fluid does density vary with temperature and pressure? a) It varies for all temperature and pressure range b) It remains constant c) It varies only for lower values of temperature and pressure d) It varies only for higher values of temperature and pressure View Answer

Answer: b Explanation: For an incompressible fluid, the change in density is negligible. Thus it does not change with temperature and pressure. 16. Specific gravity is what kind of property? a) Intensive b) Extensive c) None of the mentioned d) It depends on external conditions View Answer Answer: a Explanation: It is independent of quantity of matter present. 17. If there is bucket full of oil and bucket full of water and you are asked to lift them, which one of the two will require more effort given that volume of buckets remains same? a) Oil bucket b) Water bucket c) Equal effort will be required to lift both of them d) None of the mentioned View Answer Answer: b Explanation: Density of water is more that oil. Hence, its weight for same volume of oil will also be higher. Therefore, more effort will be required. 18. If the fluid has specific weight of 10N/m3 for a volume of 100dm3 on a planet which is having acceleration due to gravity 20m/s2 , what will be its specific weight on a planet having acceleration due to gravity 4m/s2? a) 5 N/m3 b) 50 N/m3 c) 2 N/m3 d) 10 N/m3 View Answer Answer: c Explanation: For same volume, specific weight is directly proportional to acceleration due to gravity Specific weight=4*10/20=2.

19. Should Specific Weight of incompressible fluid only be taken at STP? a) Yes, as specific weight may show large variation with temperature and pressure b) No, it can be taken for any temperature and pressure c) It should be taken at standard temperature but pressure may be any value d) It should be taken at standard pressure but temperature may be any value View Answer Answer: b Explanation: Specific weight is inversely proportional to volume. For incompressible fluid ,

variation of volume with temperature and pressure is negligible for practical consideration. Therefore, specific weight remains constant. 20. An instrument with air as fluid was involved in some experiment( specific volume was the characteristic property utilized) which was conducted during day in desert. Due to some reason experiment couldn’t be conducted during day and had to be conducted during night. However there were considerable errors in obtained values. What might be the reason of these errors? a) It was human error b) It was instrumental error c) Error was due to the fact that experiment was conducted at night d) None of the mentioned View Answer Answer: c Explanation: In Desert areas, temperature at night is considerably lower than at day. Due to this air contracts at night. Hence, it’s spe cific volume changes. As specific volume was characteristic property utilized, results obtained showed error due to change in specific volume. 2 1. A stone weighed 177 N on earth. It was dropped in to oil of specific gravity 0.8 on a planet whose acceleration due to gravity is 5m/s2. It displaced oil having weight of 100N. What was the volume of oil displaced by the stone? a) 25 Litres b) 15 Litres c) 25 m3 d) None of the mentioned View Answer Answer: a Explanation: Volume displaced=oil displaced/(specific gravity*water density* acceleration due to gravity )=100/ (0.8*1000*5).

22. An compressible fluid’s specific gravity was measured on earth, on a planet having acceleration due to gravity 5.5 times that of earth, and in space at STP. Where will it be having highest value? a) on the earth b) on the planet c) in the space d) it will be constant everywhere View Answer Answer: d Explanation: Specific gravity is characteristic property of fluid and is independent of external conditions.

23. A perfect gas A.Has zero viscosity C.Satisfies the relation PV = mRT E. None of the above Answer & Explanation

B.Has constant viscosity D.Is incompressible

Answer: Option C Explanation: 24. An ideal fluid is A.Similar to a perfect gas One which obeys Newton's law of C. viscosity One which flows through pipes with E. least friction Answer & Explanation

B.Frictionless and incompressible D.One which satisfies continuity equation

Answer: Option B Explanation: View Answer Workspace Report Discuss in Forum 25. An ideal flow of any fluid must fulfil the following: A.Newton's law of viscosity B.Newton's law of motion C.Boundary layer theory D.Pascals law E. Continuity equation Answer & Explanation Answer: Option E Explanation: View Answer Workspace Report Discuss in Forum 26. The velocity of a fluid particle at the centre of the pipe section is A.Maximum B.Minimum C.Average D.r.m.s. E. Logarithmic average. Answer & Explanation Answer: Option A Explanation: View Answer Workspace Report Discuss in Forum

27. The shear stress velocity gradient relation of the Newtonian fluids is A.Linear B.Parabolic C.Hyperbolic D.Involutic E. There is no such relation Answer & Explanation Answer: Option A Explanation: View Answer Workspace Report Discuss in Forum 28. The units of kinematic viscosity are A.kg/m2-sec C.m/kg sec E. m kg/sec. Answer & Explanation

B.kg sec/m2 D.m2/sec

Answer: Option D Explanation: View Answer Workspace Report Discuss in Forum 29. The units of dynamic viscosity are A.Newton-sec/m2 C.kg-sec/m E. m2/sec Answer & Explanation

B.Newton/m2-sec D.kg m2/sec

Answer: Option A Explanation: View Answer Workspace Report Discuss in Forum 30. The units of surface tension are A.Same as units of force C.Force/unit area E. None of the above Answer & Explanation

B.Energy/unit area D.It is dimensionless

Answer: Option B Explanation: View Answer Workspace Report Discuss in Forum

31. Density in terms of viscosity is A.Kinematic viscosity/Dynamic viscosity B.Dynamic viscosity/Kinematic viscosity Kinematic viscosity x dynamic C. D.Any of the above viscosity E. None of the above Answer & Explanation Answer: Option B Explanation: View Answer Workspace Report Discuss in Forum 32. Newton's law of viscosity relates Shear stress and rate of angular A. deformation in a fluid C.Pressure, velocity and viscosity

Yield shear stress, rate of angular deformation and viscosity Shear stress, temperature, viscosity and D. velocity B.

Pressure, vicosity and rate of angular deformation Answer & Explanation E.

Answer: Option A

Viscosity 1. Water flows between two plates of which the upper one is stationary and the lower one is moving with a velocity V. What will be the velocity of the fluid in contact with the upper plate? a) V b) N ⁄ 2 c) 2V d) 0 View Answer Answer: d Explanation: According to the No-Slip condition, the relative velocity between the plate and the fluid in contact with it must be zero. Thus, the velocity of the fluid in contact with the upper plate is 0 and that with the lower plate is V. 2. The viscous force the relative motion between the adjacent layers of a fluid in motion. Which one of the flowing fits best in the sentence? a) opposes b) never affects c) facilitates d) may effect under certain conditions View Answer

Answer: a Explanation: Viscosity is the internal friction of a fluid in motion. It is the property by the virtue of which the relative motion between two adjacent fluid layers is opposed. 3. The viscosity of a fluid in motion is 1 Poise. What will be it’s viscosity (in Poise) when the fluid is at rest? a) 0 b) 0.5 c) 1 d) 2 View Answer Answer: c Explanation: Viscosity is the property of a fluid and is constant for a given fluid under given conditions, irrespective of the fact whether the fluid is at rest or in motion. 4. Which of the following correctly states how the viscosities of a liquid and a gas will change with temperature? a) Viscosity increases with the increase in temperature of a liquid and decreases with the increase in temperature of a gas b) Viscosity increases with the increase in temperature of a liquid and increases with the increase in temperature of a gas c) Viscosity decreases with the increase in temperature of a liquid and decreases with the increase in temperature of a gas d) Viscosity decreases with the increase in temperature of a liquid and increases with the increase in temperature of a gas View Answer Answer: d Explanation: Viscosity of a liquid is due to the cohesion between it’s molecules. With the increase in temperature of a liquid, cohesion decreases , so fall in viscosity. Viscosity of a gas is due to the momentum transfer between it’s molecules. With the increase in the temperature of a liquid, molecular motion increases, leading to the increase in viscosity. 5. Which one of the following is not a unit of dynamic viscosity? a) Pa-s b) N-s/m2 c) Poise d) Stokes View Answer Answer: d

Explanation: where F= viscous force, A= area, du ⁄ dx = velocity gradient, μ = co-effcient of viscosity. Therefore,

SI unit of μ is N-s/m2 = Pa-s and CGS unit of μ is dyne-s/cm2. 1 Poise= 1 dyne-s/cm2 and 1 Stokes= 1 cm2/s. Thus, Stokes is not an unit of μ, rather it is a unit of kinematic viscosity υ. 6. Which of the following is a unit of dynamic viscosity? a) [M1 L1 T-1]. b) [M1 L-1 T-1]. c) [M1 L-2 T-2]. d) [M1 L-2 T-2]. View Answer Answer: b

Explanation: where F= viscous force, A= area, du ⁄ dx = velocity gradient, μ = co-effcient of viscosity. Therefore,

7. Which one of the following is the CGS unit of dynamic viscosity? a) Stokes b) Pa-s c) m2/s d) Poise View Answer Answer: d

Explanation: where F= viscous force, A= area, du ⁄ dx = velocity gradient, μ = co-effcient of viscosity. Therefore,

CGS unit of μ is = dyne-s/cm2. 1 Poise= 1 dyne-s/cm2 and 1 Stokes= 1 cm2/s. Thus, the CGS unit of μ will be Poise. Stokes is the CGS unit of kinematic viscosity. 8. The dynamic viscosity of a fluid is 1 Poise. What should one multiply to it to get the answer in N-s/m2? a) 0.1 b) 1 c) 10 d) 100 View Answer Answer: a Explanation: 1 Poise = 1 dyne-s/cm2 9. Which of the following is a unit of kinematic viscosity? a) Stokes b) Pa-s c) m2=s d) Poise View Answer Answer: a Explanation: ν = μ/ρ, where ν = kinematic viscosity, μ = dynamic viscosity and ρ = density of the fluid. Unit of μ is dyne-s/cm2 and that of ρ is kg/cm3. Thus, the unit of ν is cm2/s = Stokes Poise is the unit of dynamic viscosity. 1 Poise = 1 dyne-s/cm2 10. Which of the following is the dimension of kinematic viscosity? a) [L1 T-1]. b) [L1 T-2]. c) [L2 T-1]. d) [L2 T-2]. View Answer Answer: c Explanation: ν = μ/ρ, where ν = kinematic viscosity, μ = dynamic viscosity and ρ = density of the

fluid.

11. The kinematic viscosity of a fluid is 0.1 Stokes. What will be the value is m2/s? a) 10-2 b) 10-3 c) 10-4 d) 10-5 View Answer Answer: d Explanation: 1Stokes = 1cm2/s = 10-4m2/s Therefore, 0.1Stokes = 10-1cm2/s = 10-5m2/s. 12. The shear stress at a point in a liquid is found to be 0.03 N/m2. The velocity gradient at the point is 0.15 s-1. What will be it’s viscosity (in Poise)? a) 20 b) 2 c) 0.2 d) 0.5 View Answer Answer: b Explanation: where F= viscous force, A= area, du ⁄ dx = velocity gradient, μ = co-effcient of viscosity. Therefore, 13. The space between two plates (20cm*20cm*1cm), 1 cm apart, is filled with a liquid of viscosity 1 Poise. The upper plate is dragged to the right with a force of 5N keeping the lower plate stationary.

What will be the velocity in m/s of flow at a point 0.5 cm below the lower surface of the upper plate if linear velocity profile is assumed for the flow? a) 1.25 b) 2.5 c) 12.5 d) 0.25 View Answer

Answer: c Explanation: where Fν = viscous force, A = area, du ⁄ dx = velocity gradient, μ = co-effcient of viscosity. If linear velocity profile is assumed, du⁄dx = U/x, where U = velocity of the upper plate and x = distance between the two plates. Now, the viscous force Fv = -F= -5N. Substituting all the values in the equation, U becomes 12.5 m/s. 14. Two horizontal plates placed 250mm have an oil of viscosity 20 poises. Calculate the shear stress in oil if upper plate is moved with velocity of 1250mm/s. a) 20 N/m2 b) 2 N/m2 c) 10 N/m2 d) None of the mentioned View Answer Answer:c Explanation: Shear Stress = Viscosity * Velocity Gradient = 20/10* 1.25/0.25 = 10 N/m2. 15. The kinematic viscosity of oil of specific gravity .8 is .0005 .This oil is used for lubrication of shaft of diameter .4 m and rotates at 190 rpm. Calculate the power lost in the bearing for a sleeve length of 90mm. The thickness of the oil film is 1.5mm. a) 477.65 Watts b) 955.31 Watts c) 238.83 Watts d) None of the mentioned View Answer Answer: a Explanation: Power lost= torque * angular velocity = force* radius* angular velocity = shear stress * area* radius* angular velocity Shear Stress = viscosity* velocity gradient Power lost= 0.0005*0.8*1000* 2*3.142*190/60*0.2*3.142*0.23 * 190/60 = 477.65 Watts. 16. Find the kinematic viscosity of oil having density 1962 g/m3. the force experienced for area of 20 m2 is 4.904 kN and velocity of gradient at that point is 0.2/s. a) 0.625 b) 1.25 c) 2.5 d) None of the mentioned View Answer Answer: a Explanation: kinematic viscosity = dynamic viscosity / density

= (shear stress*density)/velocity gradient = (4904* 1962)/(20*0.2) = .625. 17. The velocity distribution for fluid flow over a flat plate is given by u=2y-6y2 in which u is the velocity in metre per second at a distance of y metre above the plate. Determine the shear stress at y=0.15m.Take dynamic viscosity of fluid as 8.6 poise. a) 0.172 N/m2 b) 0.344 N/m2 c) 0.086 N/m2 d) None of the mentioned View Answer Answer:a Explanation: for y = 0.15m, velocity gradient = 0.2 viscosity= shear stress/velocity gradient shear stress = 0.86*0.2 = 0.172N/m2. 18. In which types of fluids it is observed that momentum transfer dominates cohesive forces with increase in temperature and hence viscosity increases a) Gases b) Liquids c) Solids d) None of the mentioned View Answer Answer:a Explanation: It is the characteristic property of gases which show increase in viscosity with increase in temperature. 19. What is the characteristic variation shown by the thixotropic fluids in their shear stress vs. rate of shear strain graph? a) shear stress increases with increase in rate of shear strain b) shear stress decreases with increase in rate of shear strain c) shear stress shows variation only after a definite shear stress is reached d) shear stress has decreasing constant and then variation relationship with rate of shear strain View Answer Answer: c Explanation: Thixotropic fluid show a Non-Newtonian variation for shear stress vs. rate of shear strain graph after a characteristic limiting value of shear stress is reached.

20. What happens to viscosity in the case of incompressible fluids as temperature is increased? a) It remains constant b) It increases c) It decreases d) None of the mentioned View Answer Answer: c Explanation: In case of incompressible fluids, cohesive forces govern the viscosity. As temperature increases the cohesive forces between fluid molecules decreases due to increase in molecular agitation. Hence, as a result, viscosity decreases. 21. If a fluid, which has a constant specific gravity, is taken to a planet where acceleration due to gravity is 3 times compared to its value on earth, what will happen to its kinematic viscosity. a) It increases b) It decreases c) It remains constant d) None of the above View Answer Answer: c Explanation: Kinematic viscosity depends on density and dynamic viscosity. Both, density and dynamic viscosity, are independent of acceleration due to gravity. Therefore, kinematic viscosity is independent of acceleration due to gravity. 22. In liquids in order to measure the viscosity of fluid experimentally we consider the variation of shear stress with respect to what property? a) strain b) shear strain c) rate of shear strain d) none of the mentioned View Answer Answer: c Explanation: By definition, viscosity is shear stress per unit ‘rate of shear strain’. 23. For a compressible fluid the kinematic viscosity is affected by temperature and pressure variation. a) True b) False View Answer: a Explanation: Viscosity shows variation for change in temperature and pressure for compressible fluids. Hence, kinematic viscosity is affected by temperature and pressure variation.

Vapor Pressure 1. Which of the following statement is true about vapor pressure of a liquid? a) Vapor pressure is closely related to molecular activity and temperature of the liquid b) Vapor pressure is closely related to molecular activity but independent of the temperature of the liquid c) Vapor pressure is not affected by molecular activity and temperature of the liquid d) Vapor pressure is not affected by molecular activity and is independent of the temperature of the liquid View Answer Answer: a Explanation: The vapor pressure of a liquid at a given temperature is given by the pressure exerted by the saturated vapor on the liquid surface. When the vapor is saturated, an equilibrium exists between the liquid and the vapor phases. The number of molecules leaving the liquid surface is equal to the number of molecules entering the liquid surface. Hence, it is obvious that vapor pressure will be related to molecular activity and consequently to temperature. With the increase in temperature molecular activity increases as a result of which vapor pressure increases. 2. Which of the following equation correctly depicts the relation between the vapor pressure of a liquid and it’s temperature? a) Vapor pressure increases linearly with the increase in temperature of the liquid b) Vapor pressure increases slightly with the increase in temperature of the liquid at low temperatures and the rate of increase goes high at higher temperatures c) Vapor pressure increases rapidly with the increase in temperature of the liquid at low temperatures and the rate of increase goes low at higher temperatures d) Vapor pressure remains unchanged with the increase in temperature of the liquid View Answer Answer: b Explanation: Vapor pressure is closely related to molecular activity which is in turn dependant on the temperature of the liquid. With the increase in temperature molecular activity of a vapor increases slowly at first and then rapidly. Similar is the nature of variaion of vapor pressure. 3. Which of the following is the condition for the boiling of a liquid? a) Absolute pressure of a liquid must be greater than or equal to it’s vapor pressure b) Absolute pressure of a liquid must be less than or equal to it’s vapor pressure c) Absolute pressure of a liquid must be equal to it’s vapor pressure d) Absolute pressure of a liquid must be greater than it’s vapor pressure View Answer

Answer: b Explanation: As the absolute pressure of a liquid goes below it’s vapor pressure, the formation of vapor bubbles start. Thus, for boiling to start, the absolute pressure of a liquid must be less than or equal to it’s vapor pressure.

4. Which of the following machines have the possibility of cavitation? ( c r pump) a) Reaction turbines and centrifugal pumps b) Reaction turbines and reciprocating pumps c) Impulse turbines and centrifugal pumps d) Impulse turbines and reciprocating pumps View Answer Answer: a Explanation: Cavitation occurs whenever absolute pressure of a liquid drops below it’s vapor pressure. Dropping of pressure is observed mainly in reaction turbines and centrifugal pumps. 5. The three liquids 1, 2, and 3 with vapor pressures V1, V2 and V3 respectively, are kept under same pressure. If V1 > V2 > V3, which liquid will start boiling early? a) liquid 1 b) liquid 2 c) liquid 3 d) they will start boiling at the same time View Answer Answer: a Explanation: A liquid starts to boil whenever it’s absolute pressure drops below it’s vapor pressure. Thus, the absolute pressure of liquid 1 will drop early, as a result it’ll start boiling early. 6. Equal amount of a particular liquid is poured into three similar containers, namely 1, 2 and 3, at a temperature of T1, T2 and T3 respectively. If T1 < T2 < T3, the liquid in which container will have the highest vapor pressure? a) container 1 b) container 2 c) container 3 d) the vapor pressure of the liquid will remain the same irrespective of it’s temperature View Answer Answer: c Explanation: Higher the temperature, higher is the molecular activity and consequently, higher is the vapor pressure of a given liquid. Since, container 3 is at the highest temperature, liquid in it will have the highest vapor pressure. 7. The absolute pressure of a water is 0.5kN/m2 above it’s vapor pressure. If it flows with a velocity of 1m/s, what will be the value of Cavitation Number describing the flow induced boiling? a) 0.25 b) 0.5 c) 1 d) 2 View Answer Answer: c Explanation:

8. Which of the following is correct regarding the formation and collapse of vapor bubbles in a liquid? a) Vapor bubbles are formed when the fluid pressure goes above the vapor pressure and collapses when the fluid pressure goes above the bubble pressure b) Vapor bubbles are formed when the fluid pressure goes above the vapor pressure and collapses when the fluid pressure goes below the bubble pressure c) Vapor bubbles are formed when the fluid pressure drops below the vapor pressure and collapses when the fluid pressure goes below the bubble pressure d) Vapor bubbles are formed when the fluid pressure drops below the vapor pressure and collapses when the fluid pressure goes above the bubble pressure View Answer Answer: d Explanation: Whenever the absolute pressure of a fluid drops below it’s vapor pressure, bubble formation starts. Again, when the fluid pressure goes above the bubble pressure, it’ll collapse. This is how cavitation formation takes place.

Compressibility and Bulk Modulus ”. 1. Which one of the following is the correct relation between compressibility β and Bulk Modulus k a) β = k b) β = 1/k c) β = 2k d) β = k/2 View Answer Answer: b Explanation: Compressibility β of a liquid is deβned as the ratio of volumetric strain to the compressive stress while Bulk Modulus is the ratio of compressive stress to volumetric strain. Hence, β = 1/k is the correct relation. 2. Which one of the following is true about Bulk Modulus of elasticity? a) it is the ratio of compressive stress to volumetric strain b) it is the ratio of compressive stress to linear strain c) it is the ratio of tensile stress to volumetric strain d) it is the ratio of tensile stress to linear strain View Answer Answer: a Explanation: Bulk Modulus k is related to the compression of a liquid and the decrease in volume per unit volume. It is the ratio of compressive stress to the volumetric strain.

3. The value of the Bulk Modulus of elasticity for an incompressible fluid is a) zero b) unity c) infinity d) very low View Answer Answer: c Explanation: k = 1/β, where k= Bulk Modulus of elasticity and β= compressibility. For an incompressible fluid, β=0, thus the value of k will tend to infinity. 4. Three fluids 1, 2 and 3 have Bulk Moduli of k1, k2 and k3 respectively. If k1 > k2 > k3, which liquid will have the highest compressibility? a) liquid 1 b) liquid 2 c) liquid 3 d) they’ll have equal compressibilities View Answer Answer: c Explanation: k = 1=β, where k= Bulk Modulus of elasticity and β= compressibility. If k1 > k2 > k3, then β1 < β2 < β3. Thus, liquid 3 will have the highest compressibility. 5. Bulk Modulus, Pressure, Force, Stress – Which one of these won’t have the same unit as the others? a) Bulk Modulus b) Pressure c) Force d) Stress View Answer Answer: c Explanation: The SI unit of Bulk Modulus, Pressure and Stress is N/m2 but the unit of Force is N. 6. Which of the following is the dimension of Bulk Modulus? a) [M1L-1T-1]. b) [M1L-1T-2]. c) [M1L1T-2]. d) [M1L1T-1]. View Answer Answer: b Explanation:

7. Which one of the following is the unit of compressibility? a) m/N b) m2/N c) m3/N d) it is unitless View Answer Answer: b Explanation: k = 1/β, where k= Bulk Modulus of elasticity and β= compressibility.

Thus the unit of Bulk modulus is N/m2 and the unit of compressibility becomes m2/N. 8. Which of the following is the dimension of compressibility? a) [M1L1T-2]. b) [M1L1T-1]. c) [M-1L1T-2]. d) [M-1L1T2]. View Answer Answer: d Explanation: k = 1/β, where k = Bulk Modulus of elasticity and β= compressibility.

and [β] = [1/k] = [M-1L1T2].

Types of Fluids

1. The relation between shear stress Z and velocity gradient

of a fluid is given by

where A and n are constants. If n = 1, what type of fluid will it be? a) Newtonian fluid b) Non-Newtonian fluid c) Pseudoplastic d) Bingham plastic View Answer Answer: a Explanation: When n = 1, the relation reduces to Newton’s law of viscosity: z = A * , where A will represent the viscosity of the fluid. The fluid following this relation will be a Newtonian fluid.

2. The relation between shear stress Z and velocity gradient

of a fluid is given by

where A and n are constants. If n > 1, what type of fluid will it be? a) Newtonian fluid b) Dilatant c) Pseudoplastic d) Bingham plastic View Answer Answer: b Explanation: When n ≠ 1, the relation will be treated as Power law for Non-Newtonian fluids: . For n > 1, the rate of change of the shear stress increases with the increase in the value of velocity gradient. Such fluids are called Dilatants.

3. The relation between shear stress Z and velocity gradient

of a fluid is given by

where A and n are constants. If n < 1, what type of fluid will it be? a) Newtonian fluid b) Dilatant c) Pseudoplastic d) Bingham plastic View Answer

Answer: c Explanation: When n ≠ 1, the relation will be treated as Power law for Non-Newtonian fluids: . For n < 1, the rate of change of the shear stress decreases with the increase in the value of velocity gradient. Such fluids are called Pseudoplastics.

4. The relation between shear stress Z and velocity gradient

of a fluid is given by

+ B where A, n and B are constants. Which of the following conditions will hold for a Bingham plastic? a) A = 0;B ≠ 0; n ≠ 1 b) A ≠ 0;B = 0; n ≠ 1 c) A = 0;B = 0; n = 1 d) A ≠ 0;B ≠ 0; n = 1 View Answer Answer: d Explanation: For Bingham Plastics , shear stress will not remain constant after an yield value of stress. Thus, A ≠ 0;B ≠ 0. After the yield value, the relation between the shear stress and velocity gradient will become linear. hus, n = 1.

5. The relation between shear stress Z and velocity gradient

of a fluid is given by

+ B where A, n and B are constants. Which of the following conditions will hold for a Rheopectic? a) A = 0;B ≠ 0; n > 1 b) A ≠ 0;B = 0; n < 1 c) A = 0;B = 0; n < 1 d) A ≠ 0;B ≠ 0; n > 1 View Answer Answer: d Explanation: For Rheopectics, shear stress will not remain constant after an yield value of stress. Thus, A ≠ 0; B ≠ 0. After the yield value, the rate of change of the shear stress increases with the increase in the value of velocity gradient. Thus, n > 1.

6. The relation between shear stress Z and velocity gradient

of a fluid is given by

+ B where A, n and B are constants. Which of the following conditions will hold for a Thixotropic fluid? a) A = 0;B ≠ 0; n > 1 b) A ≠ 0;B = 0; n > 1

c) A = 0;B = 0; n < 1 d) A ≠ 0;B ≠ 0; n < 1 View Answer Answer: d Explanation: For Thixotropics, shear stress will not remain constant after an yield value of stress. Thus, A ≠ 0;B ≠ 0. After the yield value, the rate of change of the shear stress decreases with the increase in the value of velocity gradient. Thus, n < 1.

7. The graph shows relation between shear stress Z and velocity gradient

of a fluid is given

by where A and n are constants. The graphs are drawn for three values of n. Which one will be the correct relationship between n1, n2 and n3?

a) n1 > n2 > n3 b) n1 < n2 < n3 c) n1 > n3 > n2 d) n1 < n3 < n2 View Answer Answer: b Explanation: The graph corresponding to n = n1 represents Pseudoplastics, for which the rate of change of the shear stress decreases with the increase in the value of velocity gradient. The graph corresponding to n = n2 represents Newtonian fluids, for which shear stress changes linearly with the change in velocity gradient. The graph corresponding to n = n3 represents Dilatents, for which the rate of change of the shear stress increases with the increase in the value of velocity gradient.

8. Which of the following is a shear-thinnning fluid? a) Bingham plastic b) Rheopectic c) Dilatant d) Pseudoplastic View Answer Answer: d Explanation: Shear-thinning fluids are those which gets strained easily at high values of shear stresses. The relation between shear stress Z and velocity gradient given by Pseudoplastics.

of a shear-thinning fluid is

, where A and n are constants and n < 1. This relation is followed by

9. Which of the following is a shear-thickening fluid? a) Bingham plastic b) Thixotropic c) Dilatant d) Pseudoplastic View Answer Answer: c Explanation: Shear-thickening fluids are those for which it gets harger to strain it at high values of shear stresses. The relation between shear stress Z and velocity gradient thickening fluid is given by relation is followed by Dilatants.

of a shear-

where A and n are constants and n > 1. This

10. For what value of flow behaviour index, does the consistency index has a dimension independent of time? a) 0 b) 1 c) 2 d) 3 View Answer Answer: c Explanation: The relation between shear stress Z and velocity gradient

where A is the flow consistency index and n is the flow behaviour index.

of a fluid is given by

Thus [A] will be independent of time when n = 2.

11. What will be the dimension of the flow consistency index for a fluid with a flow behaviour index of 3? a) [M L-2 T]. b) [M L-2 T-1]. c) [M L-1 T-2]. d) [M L-1 T]. View Answer Answer: d Explanation: The relation between shear stress Z and velocity gradient

of a fluid is given by

where A is the flow consistency index and n is the flow behaviour index. Putting n = 3,

12. What will be the dimension of the flow consistency index for a fluid with a flow behaviour index of -1? a) N/m2 s2 b) N/m2 s c) N/ms d) N/ms2 View Answer Answer: b Explanation: The relation between shear stress Z and velocity gradient

of a fluid is given by

where A is the flow consistency index and n is the flow behaviour index. If n = -1, A = Z *

Unit of Z is N/m2 and

is s-1. Thus, the unit of A will be N/m2 s.

Surface Tension 1. Which of the following contribute to the reason behind the origin of surface tension? a) only cohesive forces b) only adhesive forces c) neither cohesive forces nor adhesive forces d) both cohesive forces and adhesive forces View Answer Answer: d Explanation: The molecules on the surface of a liquid experience cohesive forces due to surrounding liquid molecules acting downward and adhesive forces due to surrounding gaseous molecules acting upwards. Surface tension orginates due to this unbalanced force on the surface molecules. 2. A soap film is trapped between a frame and a wire of length 10 cm as shown.

If the surface tension is given as 0.0049 N/m, what will be the value of m (in mg) such that the wire remains in equilibrium? a) 0.1 b) 1 c) 10 d) 100 View Answer Answer: d Explanation: For the wire to be in equilibrium, Force exerted by the film on the wire due to surface tension (acting upwards) must be equal to the downward force due to the weight of the wire (acting downwards). If σ=surface tension, l=length of the wire 2σl = mg Substituting all the values, m = 2σl/g = 2 * 0.0049 * 0.01 ⁄ 9.81 = 99.9mg.

3. What will be the diameter (in mm) of a water droplet, the pressure inside which is 0.05 N/cm2 greater than the outside pressure? (Take surface tension as 0.075 N/m) a) 3 b) 0.3 c) 0.6 d) 6 View Answer Answer: c Explanation: p = 4σ/d where p = pressure difference between the liquid droplet and the surrounding medium, σ = surface tension and d = diameter of the droplet. Substituting all the values,

4. A soap bubble of d mm diameter is observed inside a bucket of water. If the pressure inside the bubble is 0.075 N/cm2, what will be the value of d? (Take surface tension as 0.075 N/m) a) 0.4 b) 0.8 c) 1.6 d) 4 View Answer Answer: b Explanation: p = 8σ/d where p = pressure difference between the bubble and the surrounding medium, σ = surface tension and d = diameter of the bubble. Substituting all the values,

5. A liquid jet of 5 cm diameter has a pressure difference of N/m2. (Take surface tension as 0.075 N/m) a) 12 b) 6 c) 3 d) 1.5 View Answer Answer: d Explanation: p = σ/d where p = pressure difference between the bubble and the surrounding medium, σ = surface tension and d = diameter of the bubble. Substituting all the values, p = 0.075 / 5 * 10-2 = 1.5 N/m2.

6. The rise in the level of a liquid in a tube is h. What will be the rise in the level if the same amount of liquid is poured into a tube of half the diameter. a) 0 b) h/2 c) h d) 2h View Answer Answer: d

Explanation: where h = rise in liquid height in the tube, S = surface tension, θ = the angle of contact, d = diameter of the tube, ρ = density of liquid and g = acceleration due to gravity. All other factors remaining constant, h α d. Thus, if d is halved, h will be doubled. 7. The ratio of the surface tension S and density ρ of liquid 1 and 2 are 1:2 and 1:4 respectively. Equal amount of the two liquids is poured into two identical tubes. what will be the ratio of the rise in the liquid level in the two tubes? (Assume the angle of contact to be same) a) 1:2 b) 2:1 c) 8:1 d) 1:8 View Answer Answer: b

Explanation: where h = rise in liquid height in the tube, S = surface tension, θ = the angle of contact, d = diameter of the tube, ρ = density of liquid and g = acceleration due to gravity. Given, S1 / ρ1 = 1 : 2 and S2 / ρ2 = 1 : 4.

8. The rise in the level of a liquid in a tube is h. If half the amount is poured outside, what will be the new rise in liquid level? a) 0 b) h/2 c) h d) 2h View Answer Answer: c Explanation: The rise in liquid level for a liquid is independent of the amount of liquid present in

the tube. Since, same tube is used and same liquid is considered, the rise in the liquid level will remain the same. 9. If a glass tube of 10 mm diameter is immersed in water, what will be the rise or fall in capillary? (Take surface tension = 0.075 N/m, g = 10 m/s2 and angle of contact = 0) a) 0.75 b) 1.5 c) 3 d) 6 View Answer Answer: c

Explanation: where h = rise in liquid height in the tube, S = surface tension, θ = the angle of contact, d = diameter of the tube, ρ = density of liquid and g = acceleration due to gravity. Substituting all the values,

10. A water drop of diameter 1 cm breaks into 1000 similar droplets of same diameter. What will be the gain or loss in the surface energy? (Take surface tension as 0.075 N/m) a) gain of 0.424 mJ b) gain of 0.212 mJ c) loss of 0.212 mJ d) loss of 0.424 mJ View Answer Answer: b Explanation: According to the Principle of Conservation of mass, M = 1000 * m, where M = mass of the big drop, m = mass of each droplet. Assuming density to be constant, D3 = 1000 * d3, i.e. D = 10d, where D = diameter of big drop, d = diameter of a droplet. Change in surface energy = Surface tension * Change in surface area = 0:075*(1000 * πd2 – πD2) = 0:075 * (10 * πD2 – πD2) = 0:075 * 9π * (10-2)2 = 0:212 mJ Since, the change is positive, there will be a gain in the surface energy

Thermodynamic Properties & Compressibility

1. If there is no exchange of heat between system and surrounding where system comprises of a compressible fluid but the heat is generated due to friction, the process is an adiabatic. a) True b) False View Answer Answer: b Explanation: For process to be adiabatic, there is no heat exchange and no heat generation within fluid. 2. For a compressible fluid, if there is no change in specific volume at constant temperature, what type of process it is? a) Isothermal process b) Adiabatic Process c) Polytropic process d) None of the mentioned View Answer Answer:a Explanation: As, specific volume remains constant, density remains constant. Therefore for given temperature there is no change in volume. hence, the process is isothermal. 3. If the fluid is incompressible, do thermodynamic properties play an important role in its behaviour at varying temperature and pressure? a) Yes b) No c) Depends on the fluid d) None of the mentioned View Answer Answer: b Explanation: If fluid is incompressible there is not much change in observed properties with variation in temperature and pressure. Hence, no perceivable change. 4. If for same temperature and pressure change, the value of bulk modulus is compared for isothermal process and adiabatic process, which one would be higher? a) Isothermal process b) Adiabatic process c) Value is constant for both the processes d) None of the mentioned View Answer Answer: b Explanation: For isothermal process K=p For adiabatic process K=kp where K=Bulk modulus

k=Polytropic constant p=Pressure. 5. The value of gas constant is same for all the gases a) True b) False View Answer Answer: b Explanation: The value of gas constant depends on molecular weight. As the molecular weight is different, gas constant will be different. 6. Calculate the pressure exerted by 9 kg of air at a temperature of 20℃ if the volume is 0.8m3. Assuming ideal gas laws are applicable. a) 946 kN/m2 b) 1892 kN/m2 c) 1419 kN/m2 d) None of the mentioned View Answer Answer: a Explanation: Ideal gas Law: PV=nRT n=M/m P=(9*8314*293)/28.97=946 kN/m2. 7. A gas weighs 16 N/m3 at 30℃ and at an absolute pressure of 0.35 N/mm2. Determine the gas constant. a) 708.23 b) 354.11 c) 531.17 d) 1062.34 View Answer Answer:a Explanation: R=P/(ρ*T)=3500000*9.81/16*303=708.23. 8. A cylinder of 0.8 m3 in volume contains superheated steam at 70℃ and .4 N/m2 absolute pressure. The superheated steam is compressed to .3 . Find pressure and temperature. a) 0.74 N/m2, 422.3℃ b) 1.48 N/m2, 422.3℃ c) 0.74 N/m2, 844.6℃ d) 1.48 N/m2, 844.6℃ View Answer Answer: a Explanation: For polytropic process,

P2=(v1/v2)n *P1 =(0.8/0.3)1.3 * 0.4 ……..(for superheated stream n=1.3) =.74 N/m2 T1=P1v1/nR=422.3℃. 9. Determine the compressibility of an incompressible fluid, if the pressure of the fluid is changed from 70 N/m2 to 130 N/m2. The volume of the liquid changes by 0.15 percent. a) 0.0025 m2/N b) 0.0050 m2/N c) 0.0070 m2/N d) 0.0012 m2/N View Answer Answer :a Explanation: Compressibility=1/Bulk Modulus =1/K K=(dp*V/dv) =60/0.15 =400 Compressibility=.0025. 10. What is the variation of cp, cv and k in case of gases when the temperature increases? a) cp and cv decreases with temperature, and k increases b) cp and cv increase with temperature, and k decreases c) cp and cv increase with temperature, and k increases d) cp and cv decreases with temperature, and k decreases View Answer Answer:b Explanation: cp is molar heat capacity at constant pressure. As temperature is increased, enthalpy increases, heat capacity increases. Same is for cv, cp is molar heat capacity at constant volume. However cp-cv=R and cp/cv = R Hence, as cp, cv increases R decreases.

Surface Tension, Capillarity, Vapour Pressure and Cavitation 1. Calculate the magnitude of capillary effect in millimeters in a glass tube of 7mm diameter, when immersed in mercury. The temperature of the liquid is 25℃ and the values of surface tension of mercury at 25℃ is 0.51 N/m. The angle of contact for mercury is 130°. a) 140 b) 280 c) 170

d) 210 View Answer Answer: a Explanation: Capillarity rise or fall h=4*cosθ*σ/ρ*g*d =4*cos130*0.51/13600*9.81*0.007 =140 mm. 2. Determine the minimum size of glass tube that can be used to measure water level if the capillary rise in the tube is restricted to 5mm. Consider surface tension of water in contact with air as 0.073 N/m a) 5.95mm b) 11.9mm c) 2.97mm d) 4.46mm View Answer Answer: a Explanation: d=4*cosθ*σ/ρ*g*h =4*1*0.073/1000*9.81*0.005 =5.95mm. 3. An oil of vicosity 7 poise is used for lubrication between shaft and sleeve. The diameter of shaft is 0.6 m and it rotates is 360 rpm. Calculate the power lost in oil for a sleeve length of 160mm. The thickness of oil film is 1.0mm a) 25.31 kW b) 50.62 kW c) 37.97 kW d) 12.65 kW View Answer Answer: a Explanation: Power lost= torque * angular velocity = force* radius* angular velocity = shear stress * area* radius* angular velocity Shear Stress = viscosity* velocity gradient Power lost= 7916.8*3.142*0.3*0.3*0.3*2*3.142*60 = 25.31 kW. 4. Find the capillarity rise or fall if a capillary tube of diameter .03m is immersed in hypothetical fluid with specific gravity 6.5, surface tension 0.25 N/m and angle of contact 147°. a) 0.44mm fall b) 0.88mm fall c) 0.44mm rise d) 0.88mm rise View Answer

Answer: a Explanation: h=4*cosθ*σ/ρ*g*d =4*cos147*0.25/6.5*1000*9.81*0.03 =-0.44 mm i.e 0.44 mm fall. 5. Will capillary rise occur and if it occurs what will be capillary rise if glass capillarity tube is immersed in water and experiment is carried out by astronauts in space. a) Capillarity rise will not occur b) Capillarity rise will occur infinitely and will come out in form of fountain c) Capillarity rise will occur finitely and will be the whole length of tube d) None of the mentioned View Answer Answer: c Explanation: Capillary rise is given by h=4*cosθ*σ/ρ*g*d hence rise is inversely proportional to g In space g is 0 m/s2 Hence, capillarity rise will occur finitely and will be the whole length of tube. 6. The surface tension of fluid in contact with air at 25℃ is 0.51N/m. The pressure inside a droplet is to be 0.05 N/cm2 greater than outside pressure. Determine the diameter of the droplet of water. a) 4.08mm b) 8.16mm c) 2.04mm d) None of the mentioned View Answer Answer: a Explanation: P=4*σ/d d= 4*.51/500 =4.08 mm. 7. If a fluid of certain surface tension and diameter is used to create a soap bubble and a liquid jet. Which of the two, bubble or liquid jet, will have greater pressure difference on the inside and outside. a) Liquid jet b) Soap bubble c) Both will have same pressure differrence d) None of the mentioned View Answer Answer: b Explanation: For soap bubble, P=8*σ/d For liquid jet, P=2*σ/d Hence, soap bubble will be having more pressure difference.

8. Capillarity fall is reduced if we take the appartus (capillary tube immersed in fluid having acute angle of contact) considerable distance inside the earth( i.e below the earth crust). a) True b) False View Answer Answer: a Explanation: Capillary rise is given by h=4*cosθ*σ/ρ*g*d Inside the earth, g (acceleration due to gravity) decreases. Hence, capillary rise will increase compared to that on the earth’s surface. 9. For liquid fluids will capillarity rise (or fall) increase or decrease with rise in temperature. a) Increase b) Decrease c) Remain constant d) First decrease then increase View Answer Answer: b Explanation: Capillary rise is given by h=4*cosθ*σ/ρ*g*d As temperature increases, σ(surface tension) decreases. Therefore, correspondingly rise(or fall) will decrease as their is direct proportional relation between the two. 10. Cavitation is more pronounced in rough pipes than smooth surfaced pipes. a) True b) False View Answer Answer: a Explanation: Rough surfaced pipes have more friction with the fluid and hence possibility of cavitation is more pronounced.

Fluid Pressure 1. What is the pressure in Pascals at a depth of 1m below the water surface? a) 98100 Pa b) 980 Pa c) 98 Pa d) 1 Pa View Answer Answer: a Explanation: It’s the summation of weights on top of the water surface. In this case, it is the weight of the atmosphere and water above 1m. [Formula: P (depth) = Patm +(density of water*gravitational constant*depth)].

2. 15 bar equals to __________ Pascals. a) 105Pa b) 1.5 x 106 Pa c) 100 Pa d) 1000 Pa View Answer Answer: b Explanation: Bar is a metric unit of pressure, but it does not fall under the SI units. One bar is exactly equal to a 100,000 Pascals. This value is taken from the atmospheric pressure on the earth at sea level. 3. The pressure at any given point of a non-moving fluid is called the ____________ a) Gauge Pressure b) Atmospheric Pressure c) Differential Pressure d) Hydrostatic Pressure View Answer Answer: d Explanation: Hydrostatic pressure varies with the increase in depth. Hydrostatic pressure is measured from the surface of the fluid because of the increasing weight of the fluid. The fluid exerts a downward force from the surface of water thus making it a non-moving fluid.

4. The device used to measure the fluid pressure is _____________ a) Hygrometer b) Calorimeter c) Manometer d) Thermometer View Answer Answer: c Explanation: Manometer is the most preferred measuring device as the pressure is measured by difference in the column heights of the manometer. It is expressed in terms of inches or centimeters of fluid making it easier for the conversion process. 5. What type of liquids are measured using a manometer? a) Heavy liquids b) Medium Liquids c) Light Liquids d) Heavy and light liquids View Answer Answer: c Explanation: Measurement of liquid in a manometer takes place through differential pressures by balancing the weight. Thus, it is easier for the manometer to measure liquids of lesser density than the heavier ones. Example of a light liquid is Water.

6. Which among these devices are the best suited for the measurement of high pressure liquids with high accuracy? a) Dead Weight Gauge b) Vacuum Gauge c) Manganin wire pressure d) Ionization Gauge View Answer Answer: c Explanation: Manganin wire is the most suitable measurement device for high pressure liquids. It has a high stability and durability on a long term basis. It also has a high hydrostatic pressure sensitivity and low strain sensitivity. 7. How do we measure the flow rate of liquid? a) Coriolis method b) Dead weight method c) Conveyor method d) Ionization method View Answer Answer: a Explanation: Coriolis concept of measurement of fluid takes place through the rotation with the reference frame. It is an application of the Newton’s Law. The device continuously records, regulates and feeds large volume of bulk materials. 8. What is the instrument used for the automatic control scheme during the fluid flow? a) Rotameters b) Pulley plates c) Rotary Piston d) Pilot Static Tube View Answer Answer: d Explanation: Pilot static tube is a system that uses an automatic control scheme to detect pressure. It has several holes connected to one side of the device. These outside holes are called as a pressure transducer, which controls the automatic scheme during fluid flow. 9. Define Viscosity? a) Resistance to flow of an object b) Resistance to flow of air c) Resistance to flow of fluid d) Resistance to flow of heat AView Answer nswer: c Explanation: Viscosity is developed due to the relative motion between two surfaces of fluids at different velocities. It happens due to the shear stress developed on the surface of the fluid.

10. What is the viscosity of water at 30oC? a) 80.1 b) 0 .801 c) 801 d) 0.081 View Answer Answer: b Explanation: A graph is plotted with temperature in the x-axis and dynamic viscosity in the yaxis. With the increase in pressure the viscosity decreases. It corresponds to an informal concept of thickness.

Pressure Distribution in a Fluid 1. Which one of the following is the unit of pressure? a) N b) N/m c) N/m2 d) N/m3 View Answer Answer: c Explanation: Pressure is defined as the force per unit area acting normal to a surface. The SI unit of force is N and area is m2. Thus, the unit of pressure will be N /m2. 2. Which one of the following is the dimension of pressure? a) [MLT2]. b) [MLT-2]. c) [ML-1T2]. d) [ML-1T-2]. View Answer Answer: d Explanation: Pressure (p) is defined as the force (F) per unit area (A) acting normal to a surface.

Thus, 3. Which one of the following statements is true regarding pressure? a) Pressure is a scalar quantity

b) Pressure is a vector quantity c) Pressure is a scalar quantity only when the area is infinitesimally small d) Pressure is a vector quantity only when the area is infinitesimally small View Answer Answer: a Explanation: Pressure is defined as the force per unit area acting normal to a surface. Both force and area are vectors, but the division of one by the other leads to a scalar quantity.

4. A beaker half-filled with water is exposed to the atmosphere. If the pressure at points A, B and C as shown are Pa, Pb and Pc respectively, which one of the following will be the relation connecting the three?

a) Pa > Pb = Pc b) Pa > Pb > Pc c) Pa < Pb < Pc d) Pa < Pb = Pc View Answer Answer: d Explanation: Since the beaker is exposed to the atmosphere, the pressure at point A will be atmospheric, Pa = 0. Pressure increases in the vertically downward direction, Pa < Pb and Pa < Pc. Pressure remains constant in the horizontal direction, Pb = Pc. Therefore, Pa < Pb = Pc. 5. A beaker is filled with a liquid up to a height h. If A and B are two points, one on the free surface and one at the base as shown, such that the minimum distance between the two is l, what will be the pressure at point B?

View Answer Answer: b Explanation: For a constant density liquid, pressure varies linearly in the vertically downward direction. Thus, PB = PA + ρgh where PB=Pressure at B, PA=Pressure at A, ρ=density of the liquid, g=acceleration due to gravity and h=vertical distance sePArating the two points. Since A is at the free surface, PA = 0, PB = ρgh. 6. A beaker of height h is filled with a liquid of density ρ up to a certain limit. The beaker is rotated by an angle θ such that further increase in the angle will result in over flow of the liquid. If the liquid surface is exposed to the atmosphere, what will be the gauge pressure at point B?

a) ρgh

b) ρgh sin θ c) ρgh cos θ d) ρgh=2 View Answer Answer: c Explanation: Vertical distance below the free surface at which the point B is located will be h cos θ. Since the pressure at the free surface is atmospheric, the gauge pressure at B will be = 0 + ρgh cos θ. 7. An arm of a teapot is completely filled with tea (density=ρ) If the arm has a length of l and is inclined at 30o to the horizontal, what will be the pressure difference between the two points, C at the mouth and D at the base of the arm?

a) ρgl b) ρgl/2 c) √2ρgl d) 2ρgl View Answer Answer: b Explanation: Vertical distance difference between the two points, C at the mouth and D at the base of the arm will be l sin θ = l sin 30o = l=2. Thus, pressure difference between C and D is = ρgl/2. 8. A beaker is filled with a liquid of density ρ1 up to a certain height. The pressure at the base of the beaker id Pb. If the liquid is replaced by an equal volume of another liquid of density ρ2, what will be the pressure at the base of the beaker now?

View Answer Answer: d Explanation: PB = ρ1gh, where h=height up to which the liquid is filled. Since equal volume of the second liquid is poured, it’ll also rise to a height of h. Thus, the pressure at the base will become

9. A beaker is filled with a liquid of density ρ1 up to a certain height. A is a point, h m downwards from the free surface of the liquid as shown. The liquid is replaced by equal volume of another liquid of density ρ2. If ρ1 > ρ2, how will the pressure at point A change?

a) remain same b) increase

c) decrease d) become zero View Answer Answer: c Explanation: P1= ρ1gh and P2 = ρ2gh, where P1 and P2 are the pressures at point A when liquids of density ρ1 and ρ2 are poured. If ρ1 > ρ2, P1 > P2. Thus the pressure at point A will decrease. 10. A beaker is filled with a liquid of density ρ1 up to a certain height. A is a point, h m downwards from the free surface such that the pressure at A is P. If the liquid is replaced by equal volume of another liquid of density ρ2, at what distance from the free surface will the pressure be P now?

View Answer Answer: c Explanation: P = ρ1gh. Let the point inside the liquid where the pressure is P be at a distance of hx from the surface. Thus, P = ρ2ghx. Hence, ρ1 * h = ρ2 * hx, ie, hx = ρ1/ρ2 h. 11. If the pressure at a point is 1m of water, what will be it’s value in terms of m of oil? (Take, the specific gravity of oil to be 0.8) a) 0.8 b) 1 c) 1.25

d) 2.5 View Answer Answer: c Explanation: Pressure at a point P is equal to ρgh, where ρ is the density and h is the height of the liquid column. Therefore, ρwater * 1 * g = ρoil * h * g, where h is the pressure in terms of m of oil. Thus, h = ρwater / ρoil = 1/0.8 = 1.25. 12. A beaker is filled with a liquid of density ρ up to a height h. If half the liquid is replaced by equal volume of another liquid of twice the density, what will be the change in the base pressure?

a) increased by ρgh b) decreased by ρgh c) increased by ρgh/2 d) decreased by ρg/h2 View Answer Answer: c Explanation: Base pressure when the beaker is filled with a liquid of density ρ up to a height h = ρgh Base pressure when half the liquid is replaced by equal volume of another liquid of twice the density = ρg h⁄2 + 2ρg h⁄2 = 3⁄2 ρgh Thus the change in base pressure is = ρgh / 2. Since, P2 > P1, there will be an increase in pressure. 13. A cuboidal contain ner (each side of 30 cm0) is completely filled with water. A is a point, 25 cm above the base such that the pressure at point A is P. At what height (in cm) from the base will the pressure be 2P?

a) 20 b) 15 c) 12.5 d) 10 View Answer

Answer: a Explanation: Pressure at a point P is equal to ρgh, where ρ is the density and h is the height of the liquid column from the top. Thus, ρ * g *(30 – h) = 2 * ρ * g *( 30-25), where h from the base where the pressure will be 2P. Thus, h = 30 – 2(30 – 25) = 20. 14. A closed tank (of height 5 m) is PArtially filled with a liquid as shown. If the pressure of the air above the fluid is 2 bar, find the pressure at the bottom of the tank. Assume the density of the liquid to vary according to the following relation: where y is the height from the base

a) 2.12 b) 2.15 c) 2.18 d) 2.5 View Answer Answer: c Explanation: The change of pressure P with vertical direction y is given by

15. The pressure gauges 1, 2 and 3 are installed on the system as shown. If the readings of the gauges be P1 = 1 bar, P2 = 2bar and P3 = 3 bar, what will be the value of P? (Take Patm = 1.01 bar)

a) 3.01 b) 4.01 c) 6.01 d) 7.01 View Answer Answer: d Explanation: PA = PAtm + P1 PB = PA + P2 PC = PB + P3 P = PC = PAtm + P1 + P2 + P3 = 1.01 + 1 + 2 + 3 = 7.01.

Pressure Distribution in a Fluid – 2

1. Three beakers 1, 2 and 3 of different shapes are kept on a horizontal table and filled with water up to a height h. If the pressure at the base of the beakers are P1, P2 and P3 respectively, which one of the following will be the relation connecting the three?

a) P1 > P2 > P3 b) P1 < P2 < P3 c) P1 = P2 = P3 d) P1 > P2 < P3 View Answer Answer: c Explanation: The pressure on the surface of the liquid in the beakers is the same. Pressure varies in the downward direction according to the formula P = ρgh, where ρ is the density of the liquid and h is the height of the liquid column from the top. P1 = ρgh P2 = ρgh P3 = ρgh Since all the beakers contain water up to to the same height, P1 = P2 = P3. 2. A beaker is filled with a liquid of specific gravity S = 1:2 as shown. What will be the pressure difference (in kN/m2) between the two points A and B, 30 cm below and 10 cm to the right of point A?

a) 2.5 b) 3.5

c) 4.5 d) 5.5 View Answer Answer: b Explanation: Pressure increases in the vertically downward direction but remains constant in the horizontal direction. Thus, PB = PA + ρgh where PB = Pressure at B, PA = Pressure at A, ρ = density of the liquid, g = acceleration due to gravity and h = vertical distance separating the two points. PB – PA = 1:2 * 103 * 9.81 * 0.3 N/m2 = 3.53 kN/m2 3. The arm of a teapot is 10 cm long and inclined at an angle of 60o to the vertical. The center of the arm base is 2 cm above the base of the beaker. Water is poured into the beaker such that half the arm is filled with it. What will be the pressure at the base of the beaker if the atmospheric pressure is 101.3 kPa?

a) 101.3 b) 101.5 c) 101.7 d) 101.9 View Answer Answer: c Explanation: Total height of the water in the beaker = 2 + 1⁄2 * 10 cos 60o cm = 4:5 cm. Pressure at the base of the beaker = 101.3 + 103 * 9.81 * 0.045 Pa = 101.3 + 0.44 kPa = 101.74 kPa. 4. A beaker of height 10 cm is half-filled with water (Sw = 1) and half-filled with oil (So = 1). At what distance (in cm) from the base will the pressure be half the pressure at the base of the beaker?

a) 4.375 b) 4.5 c) 5.5 d) 5.625 View Answer Answer: b Explanation: Gauge pressure at the base of the beaker = So * 103 * 0.05 * g + Sw * 103 * 0.05 * g = 882.9Pa. Let the required height be h m from the base. If 0.05 ≤ h < 0.1, 800(0.1 – h)g = 1⁄2 * 882.9 Thus, h = 0.04375 (out of the range considered). If 0 < h ≤ 0:05, 800 * 0.05 * g + 103 * (0.05 – h) * g = 1⁄2 * 882.9 Thus, h = 0.045 (in the range considered). Hence, the correct answer will be 45 cm. 5. A beaker of height 30 cm is filled with water (Sw = 1) up to a height of 10 cm. Now oil (So = 0:9) is poured into the beaker till it is completely filled. At what distance (in cm) from the base will the pressure be one-third the pressure at the base of the beaker?

a) 27.33 b) 19.2 c) 10.8 d) 2.67 View Answer

Answer: b Explanation: Gauge pressure at the base of the beaker = So * 103 * 0.2 * g + Sw * 103 * 0.1 * g = 2550.6Pa. Let the required height be h m from the base. If 0.1 ≤ h < 0.3, 800(0.3 – h)g = 1⁄3 * 2550.6 Thus, h = 0.192 (in the range considered). Even if there’s no need to check for the other range, it’s shown here for demonstration purpose.If 0 < h ≤ 0.1, 800 * 0.2 * g + 103 * (0.2 – h) * g = 1⁄3 * 2550.6 Thus, h = 0.2733 (out of the range considered). Hence, the correct answer will be 19.2 cm. 6. An oil tank of height 6 m is half-filled with oil and the air above it exerts a pressure of 200 kPa on the upper surface. The density of oil varies according to the given relation: What will be the percentage error in the calculation of the pressure at the base of the tank if the density is taken to be a constant equal to 800?

a) 0.01 b) 0.05 c) 0.10 d) 0.15 View Answer Answer: a Explanation: The change of pressure with the vertical direction y is given by dP/dy = – ρg dP = -ρg dy If Pa and Pb be the pressures at the top and bottom surfaces of the tank,

Thus, Pb = 223.5746kPa. If the density is assumed to be constant,

Pb = 200 + 800 * 9.81 * 3 * 103 = 223.544 kPa. Hence, precentage error

7. If a gas X be confined inside a bulb as shown, by what percent will the pressure of the gas be higher or lower than the atmospheric pressure? (Take the atmospheric pressure equal to 101.3 kPa)

a) 4:75% higher b) 4:75% lower c) 6:75% higher d) 6:75% lower View Answer Answer: a Explanation: Pa = Patm = 101.3 Pb = Pa + 0.9 * 9.81 * 0.03 = 101.56 Pc = Pb + 13.6 * 9.81 * 0.04 = 106.9 Pd = Pc – 1 * 9.81 * 0.05 = 106.41 Pe = Pd – 0.9 * 9.81 * 0.04 = 106.1 PX = Pe = 106.1 Since, PX > Patm, the percentage by which the pressure of the gas is higher than the atmospheric p ressure will be 8. A tank of height 3 m is completely filled with water. Now two-third of the liquid is taken out and an equal amount of two other immiscible liquids of specific gravities 0.8 and 1.2 are poured into the tank. By what percent will the pressure at the base of the tank change?

a) 0% b) 5%higher c) 5%lower d) 10%higher View Answer Answer: a Explanation: Pressure at the base initially = 1 * 9.81 * 3 = 29.43 kPa; Pressure at the base after adding the other two liquids= 0.8 * 9.81 * 1 + 1 * 9.81 * 1 + 1.2 * 9.81 * 1 kPa; Thus the pressure at the base remains the same. 9. A beaker of height 15 cm is completely filled with water. Now two-third of the liquid is taken out and an equal amount of two other immiscible liquids of specific gravities 0.8 and 1.2 are poured into the tank. What will be the pressure (in kPa) at a point situated at a height, half the height of the beaker?

a) 588.6 b) 637.65 c) 735.75 d) 833.85 View Answer Answer: b Explanation: PA = 0.8 * 103 * 9.81 * 0.05 + 1 * 103 * 9.81 * 0.025 = 637.65 kPa.

10. A beaker of height h is completely filled with water. Now two-third of the liquid is replaced by another liquid. If the pressure at the base of the beaker doubled, what is the specific gravity of the liquid poured? a) 0.5 b) 1 c) 2 d) 2.5 View Answer Answer: d Explanation: Pressure at the base initially = Sw * h⁄3 * g; Pressure at the base after pouring the second liquid = Sw * h⁄3 * g + Sl * 2h⁄3 * g, where Sw and Sl are the specific gravities of water and the second liquid.

11. A beaker, partially filled with a liquid is rotated by an angle 30o as shown. If the pressure at point B becomes 12 bar, what will be the height (in cm) of the beaker?

a) 23.5 b) 24.5 c) 26.5 d) 27.5 View Answer Answer: b Explanation: If the height of the beaker is h, the pressure at point B = 103 * g * h * cos 30o = 12 * 103kPa; h = 24.5 cm. 12. A beaker of height 15 cm is partially filled with a liquid and is rotated by an angle θ as shown. If the pressure at point B becomes 5 bar, what will be the value of θ?

a) 30o b) 50o c) 60o d) 70o View Answer Answer: d Explanation: If the angle of inclination is taken to be θ, the pressure at point B = 103 * g * 0.15 * cos θ = 5 * 103 kPa; θ = 70.12o.s 13. A beaker of height 30 cm is partially filled with a liquid and is rotated by an angle θ as shown. At this point, the pressure at point B is found to be 5 bar. By what angle should θ be increased such that the pressure at B gets halved?

a) 12o b) 15o c) 17o d) 20o View Answer Answer: b Explanation: Let θ1 and θ2 be the angles at which the beaker is inclided for the two cases mentioned. 103 * 9.81 * 0.15 * cos θ1 = 5 * 100; θ1 = 70.12o

103 * 9.81 * 0.3 * cos θ2 = 1⁄2 * 5 * 100; θ1 = 85.12o θ2 – θ1 = 15o 14. A closed tank (each side of 5 m) is partially filled with fluid as shown. If the pressure of the air above the fluid is 2 bar, find the pressure at the bottom of the tank. Assume the density ρ of the fluid to vary according to the given relation:

a) 766 b) 776 c) 786 d) 796 View Answer Answer: c Explanation: PA = Patm = 760 PB = PA + 30 PC = PB – 50 / 13.6 = 786.32 PX = PC = 786.3. 15. For what height of the mercury column will the pressure inside the gas be 40 cm Hg vacuum?

a) 36 b) 40 c) 76 d) 116 View Answer Answer: b Explanation: Pgas = Patm – ρgH Taking gauge pressure in terms of cm of Hg, -40 = 0 – H; H = 40.

Fluid Pressure at a Point and Pascal’s Law 1. A Hydraulic press has a ram of 30 cm diameter and a plunger of of 2 cm diameter. It is used for lifting a weight of 35 kN. Find the force required at the plunger. a) 233.3 kN b) 311.1 kN c) 466.6 kN d) 155.5 kN View Answer Answer: d Explanation: F/a=W/A F=(35000*3.142*.02*.02)/(3.142*0.3*0.3) =155.5 kN. 2. The pressure at a point in the fluid is 4.9 N/cm2. Find height when the fluid under consideration is in oil of specific gravity of 0.85. a) 5.83 m b) 11.66 m c) 17.49 m d ) 8.74 m View Answer Answer: a Explanation: Height=p/ρg =48620/850*9.81 =5.83 m. 3. An open tank contains water upto a depth of 350 cm and above it an oil of specific gravity 0.65 for a depth of 2.5 m. Find the pressure intensity at the extreme bottom of the tank. a) 5.027 N/cm2 b) 10.05 N/cm2 c) 2.51 N/cm2 d) None of the mentioned View Answer

Answer: a Explanation: p= (specific gravity of water* height of water + specific gravity of oil* height of oil) * 9.81 = 5.027 N/cm2. 4. The diameters of a small piston and a large piston of a hydraulic jack are 45 mm and 100 mm respectively.Force of 0.09 kN applied on smaller in size piston. Find load lifted by piston if smaller in size piston is 40 cm above the large piston. The density of fluid is 850 kg/m3 a) 60 N/cm2 b) 12 N/cm2 c) 30 N/cm2 d) None of the mentioned View Answer Answer: a Explanation: Pressure at bottom of tank =ρgh + F/a =850*9.81*0.4 + 90/3.142*0.045*0.045 =60 N/cm2. 5. If fluid is at rest in a container of a narrow mouth at a certain column height and same fluid is at rest at same column height in a container having broad mouth, will the pressure be different at certain depth from fluid surface. a) Pressure will be same for both. b) Pressure will be more for narrower mouth c) Pressure will be less for narrower mouth d) None of the mentioned View Answer Answer: a Explanation: As per hydrostatic law, the pressure depends only on the height of water column and not its shape. 6. We can draw Mohr’s circle for a fluid at rest. a) True b) false View Answer Answer: b Explanation: Mohr’s circle is used to denote shear stress distribution. For fluid at rest, there is no shear stress. Hence, we cannot draw Mohr’s circle for fluid at rest. 7. Pressure intensity or force due to pressure gradient for fluid at rest is considered as which kind of force? a) Surface force b) Body force c) Force due to motion d) None of the mentioned View Answe r

Answer: a Explanation: Pressure force is surface force. 8. Calculate the hydrostatic pressure for water moving with constant velocity at a depth of 5 m from the surface. a) 49 kN/m2 b) 98 kN/m2 c) since fluid is in motion, we cannot analyse d) None of the mentioned View Answer Answer: a Explanation: If fluid is moving with uniform velocity we treat it analytically same as if fluid is at rest p= ρgh. 9. Pressure distribution for fluid at rest takes into consideration pressure due to viscous force. a) True b) False View Answer Answer: b Explanation: Viscous force term in pressure expression for fluid at rest is absent as their is no motion of liquid. 10. Barometer uses the principle of fluid at rest or pressure gradient for its pressure calculation. a) True b) False View Answer Answer: a Explanation: Principle of Barometer is Hydrostatic law.

Measurement of Pressure, Simple and Differential Manometers 1. The right limb of a simple U-tube manometer containing mercury is open to the atmosphere while the lift limb is connected to a pipe in which a fluid of specific gravity 0.85 is flowing. The centre of the pipe is 14 cm below the level of mercury in the right limb.Evaluate the pressure of fluid flowing in the pipe if the difference of mercury level in the two limbs is 22 cm. a) 2.86 N/cm

2

b) 5.73 N/cm c) 1.43 N/cm

2

2

d) None of the mentioned View Answer

Answer: a Explanation: Pressure at centre of pipe + Pressure at depth 8 cm in left limb = Pressure at depth 22 cm in right limb P = 13600×9.81×0.22 – 850×9.81×.08 = 2.86 N/cm2.

2. A single coloumn manometer is connected to a pipe containing a liquid of specific gravity 0.75. Find the pressure in the pipe if the area of reservoir is 250 times the area of tube for the manometer reading. The difference in mercury level is 40 cm. On the left limb the fluid is upto the height of 20 cm. a) 10.42 N/cm b) 5.21 N/cm c) 2.60 N/cm

2

2

2

d) None of the mentioned View Answer Answer: b Explanation: Pressure = a/A height × (density of mercury × 9.81-density of fluid × 9.81)+ height in right limb × density of mercury × 9.81 – height in left limb × density of fluid × 9.81 = 5.21 N/cm2 { Here a/A = 1/ 250}.

3. A Differential manometer is connected at the points A and Bat the centre of two pipes. The pipe A(left limb) contains a liquid of specific gravity = 1.5 while pipe B (right limb)contains a liquid of specific gravity 0.85. The pressure at A and B are .5 kgf/cm and 1.2 kgf/cm2 respectively. Find the 2

difference in level of mercuru in the differential manometer. A is 2.5m above B and 5 m above the mercury in its own limb. B is 2.5 m above the mercury level in limb A. a) 12.7 cm b) 25.5 cm c) 6.28 cm d) 10.85 cm View Answer Answer: a Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B\ 0.5*9.81*10000 + 5*9.81*1500 + h*9.81*13600 = 1.2*9.81*10000 + (h+2)*9.81*850 After solving, h=12.7 cm.

4. An inverted differential manometer is connected to two pipes A and B which covey water. The fluid in manometer is oil of specific gravity 0.75. For the manometer readings, find the pressure difference between A and B. Datum in left limb is 40 cm above point A. Point B is 60 cm below datum line. Difference in level of fluid is 20 cm. a) 1471 N/m

2

b) 2943 N/m

2

c) 735.75 N/m

2

d) None of the mentioned View Answer Answer: a Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B Pressure difference between A and B = -0.4*9.81*100 + 0.2*9.81*750 + 0.4*9.81*1000 = 1471 N/m2.

5. In the inverted U-tube Differential manometer, how is the specific gravity of manometric fluid used relative to the fluid flowing in the pipes a) Specific gravity is more than that of fluid flowing in pipes b) Specific gravity is less than that of fluid flowing in pipes c) Specific gravity is equal to that of fluid flowing in pipes d) None of the mentioned View Answer Answer: b Explanation: In the inverted U-tube Differential manometer, specific gravity of manometric fluid used is less than relative to the fluid flowing in the pipes as the manonmetric fluid is at the top.

6. Why is large reservoir used in single column manometer? a) In order to enhance the change in level of liquid in reservoir b) In order to negate the effects of change in level due to pressure variation c) In order to reduce the effect due to dynamic pressure variation due to motion d) None of the mentioned View Answer Answer: b Explanation: Single column manometer directly gives the pressure by measuring the height in the other limb and due to large cross sectional area of the reservoir, for any variation in pressure, the change can be neglected.

7. Manometers are the pressure measuring devices which use the principle of dynamic pressure to measure the pressure difference. a) True b) False View Answer Answer: b Explanation: Manometers are the pressure measuring devices which use the principle of pressure due to static fluid (i.e the column height) to measure the pressure difference.

8. The distance moved by liquid will be more in which type of manometer? a) Inclined Single coloumn manometer b) Vertical Single coloumn manometer c) Horizontal Single coloumn manometer d) None of the mentioned View Answer

Answer: a Explanation: The distance moved by liquid will be more in Inclined Single column manometer due to its inclination.

9. Differential manometer gives the pressure reading with respect to atmospheric pressure. a) True b) False View Answer Answer: b Explanation: Differential manometer gives the pressure difference between the fluid flowing in two pipes with respect to each other.

10. Which device is popularly used for measuring difference of low pressure? a) Inverted U-tube Differential Manometer b) U-tube Differential Manometer c) Inclined Single column manometer d) Vertical Single column manometer View Answer Answer: a Explanation: Inverted U-tube Differential Manometer has lighter manometric fluid, Hence it is used for measuring the low pressure difference.

Fluid Mechanics Questions and Answers – Manometer This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Manometer”. 1. In a stationary fluid, how does the local pressure of the fluid vary? a) With depth only b) In the horizontal direction only c) Both with depth and along horizontal direction d) Neither with depth nor along horizontal direction View Answer Answer: a Explanation: According to Pascal’s law, the local pressure of a fluid is same in all directions. Hence, the pressure won’t vary along the x and y direction. The local pressure will increase with an increase in depth due to the extra weight of water column above that point. 2. Which of the following cannot be the value of absolute pressure of a fluid at any point? a) 0 b) 1.013 bar c) – 1 bar d) 200 bar View Answer

Answer: c Explanation: Absolute zero pressure is the reference used for the measurement of absolute pressure. Absolute zero pressure is possible (theoretically). Hence, 0 and positive values are possible, but a negative value is impossible. 3. A student wants to find the absolute pressure of water at a point below the surface of water. He has a barometer and a manometer pressure gauge. The barometer reads 1.3152 bar where as the manometer pressure gauge reads 0.3152 bar. What is the absolute pressure? (Assume that pressure at one end of the manometer is atmospheric.) a) 1 bar b) 1.6304 bar c) 0.3152 bar d) 1.3152 bar View Answer Answer: b Explanation: The options may tempt you to subtract the readings, but the concept of barometer and manometer is important. Barometer measures the atmospheric pressure whereas, the manometer reads the gauge pressure. Hence, we need to add the two values. 4. In a U-tube manometer, one end is open to the atmosphere, the other end attached to a pressurized gas of gauge pressure 40 kPa. The height of the fluid column in the atmospheric side is 60 cm, and that on the gas side is 30 cm. The manometic fluid used is: (Take g = 9.8 m/s2). a) Water b) Liquid ammonia c) Oil d) Mercury View Answer Answer: d Explanation: Gauge pressure = 40000 Pa. Height difference = 60 – 30 = 30 cm = 0.3 m. ρ*g*(h 2 – h1) = 40000. We get, ρ = 13605 kg/m3 = Density of mercury. 5. In a U-tube mercury manometer, one end is exposed to the atmosphere and the other end is connected to a pressurized gas. The gauge pressure of the gas is found to be 40 kPa. Now, we change the manometric fluid to water. The height difference changes by: (ρmercury = 13600 kg/m3, ρwater = 1000 kg/m3). a) 1260% b) 92.64 % c) Remains unchanged (0%) d) 13.6% View Answer Answer: a Explanation: Since the gauge pressure remains the same ρ*(h2 – h1) = constant. The height difference in mercury manometer is 0.30 m and that in a water manometer is 4.08 m. Percent change is thus, 1260%. Be careful about the denominator used for computing percent change.

6. A manometric liquid should suitably have _________ a) Low density & Low Vapour pressure b) Low density & High Vapour pressure c) High density & Low Vapour pressure d) High density & High Vapour pressure View Answer Answer: c Explanation: A high density is favourable because the height of the column required for the manometer would be low. A liquid with high vapour pressure would be less sensitive to changes in pressure and may result in a slower rise of the manometric fluid. Thus, a fluid with low vapour pressure is favourable. 7. A simple U-tube manometer can measure negative gauge pressures. a) True b) False View Answer Answer: a Explanation: The height of the manometric fluid in a U-tube manometer in the test column would fall if there is a positive gauge pressure. The height would increase if there is a negative gauge pressure. It is possible to measure negative gauge pressures with a U-tube manometer. However, the negative pressure cannot fall below -1 Bar. 8. Both ends of a U-tube manometer are exposed to the atmosphere. There exists a possibility that the height difference of the manometer is non-zero. True or False? a) True b) False View Answer Answer: a Explanation: The height difference may be non-zero when there are multiple immiscible fluids used in the same manometer. Even though the pressure is same on both surfaces, the height would be different as the fluid with higher density will be at a lower height. 9.The below figure shows an inclined U-tube mercury manometer. The vertical end of the tube is exposed to a gas of gauge pressure 50 kPa and the inclined end is exposed to the atmosphere. The inclined part of the tube is at an angle of 30o with the horizontal. Find the value of h (in cm) (take g = 9.8 m/s2, ρmercury = 13600 kg/m3)

a) 60 b) 50 c) 75 d) 25 View Answer Answer: c Explanation: Pressure along the dotted line will be 50 kPa. Gauge pressure in an inclined manometer is given by P = ρ.g.h.sin (Ɵ). Substituting P, ρ and Ɵ, we get the value of h as 0.75 m. 10. In the manometer given above, 2 immiscible fluids mercury (ρ = 13600 kg/m 3) and water (ρ = 1000 kg/m3) are used as manometric fluids. The water end is exposed to atmosphere (100 kPa) and the mercury end is exposed to a gas. At this position, the interface between the fluids is at the bottom most point of the manometer. Ignore the width of the manometer tube and the radius of curvature. The value of h is found to be 9.45 m. The height of the mercury column is given to be 75 cm. Find the gauge pressure of the gas. (g = 9.8 m/s2)

a) 100 kPa b) 50 kPa

c) 200 kPa d) 0 kPa View Answer Answer: d Explanation: Height of water column = 0.75 + 9.45 = 10.2 m. We equate the pressures at the bottom most point. Pa + ρw.g.(10.2) = Pg + ρm.g.(0.75). We find, Pg = 100 kPa = Absolute pressure. Hence, gauge pressure will be 0.

Fluid Mechanics Questions and Answers – Bouyancy This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Bouyancy”. 1. Find the position of centre of buoyancy for a wooden block of width 3.5 m and depth 1 m, when it floats horizontally in water. The density of wooden block id 850 kg/m3 and its length 7.0 m. a) 0.95 b) 0.85 c) 1.05 d) 1.65 View Answer Answer: b Explanation: Weight of the block=ρ*g*Volume=850*9.81*7*3.5*1=204.29 kN Volume of

water displaced= Weight of water displaced/weight density of water = 20.825 m3. h=20.825/3.5*7=0.85 m.

2. A stone weighs 450 N in air and 200 N in water. Compute the volume of stone. a) .025 m b) .05 m

3

3

c) .075 m

3

d) None of the mentioned View Answer Answer: a Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water =250 Volume of water displaced=Volume of stone=250/9.81*1000=0.025 m3.

3. A stone weighs 650 N in air and 275 N in water. Compute its specific gravity. a) 1.73 b) 2.45 c) 3.46 d) 0.865 View Answer Answer: a Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water =375 Volume of water displaced=Volume of stone=375/9.81*1000=0.038 m3 Density of stone= mass/volume=650/9.81*0.038=1733 kg/m3 specific gravity= Density of stone/Density of water=1.73.

4. A body of dimensions 2.7 m * 3.8 m * 2.5 m, weighs 2500 N in water.Find its weight in air. a) 254.12 kN b) 508.25 kN c) 101.65 kN d) 127.06 kN View Answer Answer: a Explanation: Weight of stone in air = Weight of water displaced+Weight of stone in water = 9.81*1000*2.7*3.8*2.5+2500=254.12 kN.

5. Find the density of metallic body which floats at the interface of mercury of sp.gr 13.6 and water such that 40 % of its volume is sub-merged in mercury and 60% in water. a) 6040 kg/m

3

b) 12080 kg/m c) 24160 kg/m d) 3020 kg/m

3

View Answer

3

3

Answer: a Explanation: Total Bouyant force=Force of bouyancy due to water+Force of bouyancy due to mercury For equilibrium, Total bouyant force= Weiht of body 1000*9.81*0.6*V + 13.6*1000*9.81*0.4*V=ρ*g*V ρ=6040 kg/m3.

6. What is the principal cause of action of buoyant force on a body submerged partially or fully in fluid? a) Displacement of fluid due to submerged body b) Development of force due to dynamic action c) Internal shear forces mitigating external forces d) None of the mentioned View Answer Answer: a Explanation: The principal cause of action of buoyant force on a body submerged partially or fully in fluid is the force equal in magnitude to the weight of the volume of displaced fluid.

7. How can relatively denser object be made to float on the less dense fluid? a) By altering the shape. b) By altering the forces acting on the object c) By altering the shear forces acting on the object d) None of the mentioned View Answer Answer: a Explanation: By changing the shape of an object it can be made to float on a fluid even if it is denser than that fluid. This principle is used in ship building.

8. What happens to the buoyant force acting on the airship as it rises in the air? a) Buoyant force increases b) Buoyant force decreases c) Buoyant force remains constant d) Buoyant force first increases then shows decrease View Answer Answer: b Explanation: Buoyant force acting on the airship decreases as it rises in the air as air at higher altitude becomes rarer and its density decreases.

9. As a balloon rises in the air its volume increases, at the end it acquires a stable height and cannot rise any further. a) True b) False View Answer Answer: a Explanation: As balloon rises in air, pressure acting on it reduces and therefore its volume increases. Also, a rising balloon ceases rising when it and the displaced air are equal in weight.

10. Submarines use principle of ‘neutral buoyancy’ to go into the water. a) True b) False View Answer Answer: a Explanation: To dive, the submarine tanks are opened to allow air to exhaust, while the water flows in. When the weight has been balanced so the overall density of the submarine is equal to the water around it, it has neutral buoyancy and hence will go down.

Fluid Mechanics Questions and Answers – Metacentre and Metacentric Height This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Metacentre and Metacentric Height”. 1. A rectangular pontoon is 5 m long, 3 m wide and 1.40 m high. The depth of immersion of the pontoon is 0.60 m in seawater. If the centre of gravity is 0.7 m above the bottom of the pontoon, determine the metacentric height. The density for seawater = 1045 kg/m3. a) 0.135 b) 0.271 c) 0.543 d) 0.068 View Answer Answer: a Explanation: BG=Centre of pontoon – Centre of immersed portion=0.7-0.3=0.4 Metacentric height=I/∀ -BG I=bd³/12 = 5*3³/12 ∀=5*3*1.4 Metacentric height=0.135 m. 2. A uniform body of size 4 m long * 2.5 m wide * 1.5 m deep floats in water. What is the weight of the body if depth of immersion is 1 m ? a) 147.1 kN b) 294.3 kN c) 73.5 kN d) 588.6 kN View Answer Answer: a Explanation: Weight of Body = Weight of water displaced = ρ*g*Volume of displaced water=9.81*1000*4*2.5*1.5=147.1kN.

3. A block of material of specific gravity 0.45 floats in water. Determine the meta-centric height of the block if its size is 3 m * 2 m* 0.8 m. a) 0.506 m b) 0.376 m c) 1.012 m d) 0.127 m View Answer Answer: b Explanation: BG= Centre of pontoon – Centre of immersed portion=0.4 – 0.55*0.8=0.04 Metacentric height=I/∀ -BG I=bd³/12 = 3*2³/12 ∀=3*2*0.8 Metacentric height=0.376 m. 4. A solid cylinder of diameter 4.5 has a height of 2.5 metres. Find the meta-centric height of the cylinder when it is floating in water with its axis vertical. The sp. gr. of the cylinder=0.45. a) 1.9 m b) 3.8 m c) 5.7 m d) .95 m View Answer Answer: a Explanation:BG= Centre of pontoon – Centre of immersed portion=1.25-0.45*2.5=0.125 Metacentric height=I/∀ -BG I=π*r⁴ ∀= π*r*r*h Metacentric height=1.9 m. 5. In case of spherically shaped bodies of uniform mass distribution and completely immersed in fluid and floating, the centre of buoyancy coincides with centre of gravity. a) True b) False View Answer Answer: a Explanation: The volume of fluid displaced by the body is equal to the actual volume of body in air. Hence, In case of spherically shaped bodies of uniform mass distribution and completely immersed in fluid and floating, the centre of buoyancy coincides with centre of gravity. 6. Proper explanation for metacentre is: a) Point at which line of action of force meets the normal axis of body when it is given angular displacement b) Intersection of line passing through new centre of buoyancy and centre of gravity. c) point about which body starts oscillating when it is given small angular displacement d) All of the mentioned View Answer

Answer: d Explanation: All of the above explanation are apt. 7. The metacentric height is affected by the change in density. a) True b) False View Answer Answer: True Explanation: Metacentre does depend on the density. Hence, the metacentric height is affected by the change in density. 8.For a completely immersed body, the metacentric height is always zero. a) True b) False View Answer Answer: b Explanation: The metacentric height may or may not be zero as metacentre will not always coincide with centre of gravity. 9. Meta centre always lies below the centre of gravity a) True b) False View Answer Answer: b Explanation: It depends on the stability of floating body. 10. The principle of floatation of bodies is based on the premise of a) Metacentre b) Newtons first law c) Newtons law of viscosity d) None of the mentioned View Answer Answer: a Explanation: The principle of floatation of bodies is based on the premise of Metacentre.

Fluid Mechanics Questions and Answers – Conditions of Equilibrium of a Floating and Submerged Bodies This set of Fluid Mechanics Multiple Choice Questions & Answers focuses on “Conditions of Equilibrium of a Floating and Submerged Bodies”.

1. A solid cylinder of diameter 5.0 m has a height of 6.0 m. Find the meta-centric height of the cylinder if the specific gravity of the material of cylinder 0.45 and it is floating in water with its axis vertical. State whether the equilibrium is stable or unstable. a) -0.29 m b) -0.61 m c) -1.16 m d) 0.14 m View Answer Answer: b Explanation: BG=Centre of pontoon – Centre of immersed portion=0.3-0.45*0.3=1.65 Metacentric height=I/∀ -BG I=π*r⁴=π*2.5⁴ ∀=π*r*r*h=π*2.5*2.5*6 Metacentric height=-0.61. 2. A solid cylinder of 15 cm diameter and 40 cm long, consists of two parts made of different materials. The first part at the base is 1.5 cm long and of specific gravity=6.5. The other part of the cylinder is made of the material having specific gravity 0.75. State, if the it can float vertically in water. a) It will float b) It will not float c) Data insufficient d) None of the mentioned View Answer Answer: a Explanation: AG=(weight of base*distance of C.G from base point A) + (weight of upper part*distance of C.G from point A)/ )weight of base + weight of upper part) = 14.52 By principle of buoyancy, Weight of cylinder = Weight of water displaced h=38.625 AB=19.31 BG=14.25-19.31= -4.79 GM= Metacentric height=I/∀ -BG = 6.16 As metacentric height is positive, it will float. 3. A wooden cylinder of sp.gr. = 0.6 and circular in cross-section is required to float in oil(sp.gr. = 0.90). Find the L/D ratio for the cylinder to float with its longitudinal axis vertical in oil, where L is the height of cylinder and D is its diameter. a) L/D<9/16 b) L/D<3/4 c) L/D<2/3 d) None of the mentioned View Answer

4. A cylinder(uniform density distribution) of radius 3.0 m has a height of 9.0 m. The specific gravity of the material of cylinder 0.85 and it is floating in water with its axis vertical. State whether the equilibrium is stable or unstable. a) Stable b) Unstable c) Insufficient Data d) None of the mentioned View Answer Answer: a Explanation: BG=Centre of pontoon – Centre of immersed portion=0.3-0.45*0.3=1.65 Metacentric height=I/∀ -BG I=π*r⁴=π*3⁴ ∀=π*r*r*h=π*3*3*9 Metacentric height=0.325. 5. If the magnitude of dimension of a rectangular wooden block is length>breadth>height, then for it to float on the water, it should be immersed in what manner? a) It should be immersed vertically such that length is partially immersed b) It should be immersed horizontally such that breadth is partially immersed c) It should be immersed such that height is partially immersed d) None of the mentioned View Answer Answer: b Explanation: When it is immersed in such a manner where height is partially immersed, its stability is most as moment of inertia is most about that axis. 6. When body is completely or partially immersed in a fluid, how much its weight be distributed for it to be in stable equilibrium. a) Around the lower part b) Around the upper part c) Is independent of weight distribution d) None of the mentioned View Answer Answer: a Explanation: When the weight distribution is around the lower part, the centre of gravity is at lower portion and hence below the centre of buoyancy which is condition for stable equilibrium. 7. In unstable equilibrium what is the relation between forces? a) Buoyancy force= Weight of body b) Buoyancy force > Weight of body c) Buoyancy force < Weight of body d) None of the mentioned View Answer Answer: a Explanation: Fb=W and the the centre of buoyancy is below the centre of gravity.

8. The floating body is said to be in unstable equilibrium if the metacentre is below the centre of gravity. a) True b) False View Answer Answer: b Explanation: The floating body is said to be in unstable equilibrium if the metacentre is above the centre of gravity. 9. The floating body is said to be in neutraL equilibrium if the metacentre is above the centre of gravity. a) True b) False View Answer Answer: b Explanation: The floating body is said to be in unstable equilibrium if the metacentre coincides with the centre of gravity. 10. In stable equilibrium for completely submerged bodies what is the relation between forces? a) Buoyancy force= Weight of body,the centre of buoyancy is below the centre of gravity. b) Buoyancy force=Weight of body, the centre of buoyancy is above the centre of gravity. c) Buoyancy force < Weight of body d) None of the mentioned View Answer Answer: b Explanation: Fb=W and the the centre of buoyancy is above the centre of gravity.

Bernoulli’s Equation for Real Fluids and Applications of Bernoulli’s Equation 1. Which is the cheapest device for measuring flow / discharge rate. a) Venturimeter b) Pitot tube c) Orificemeter d) None of the mentioned View Answer Answer: c Explanation: Orificemeter is the cheapest availab le device for measuring flow/discharge rate.

2. The principle of Orificemeter is same as that of Venturimeter. a) True b) False View Answer Answer: a Explanation: The working principle for both Orificemeter and Venturimeter is same. 3. What is the relationship between Orificemeter diameter and pipe diameter a) Orificemeter diameter is 0.5 times the pipe diameter b) Orificemeter diameter is one third times the pipe diameter c) Orificemeter diameter is one fourth times the pipe diameter d) Orificemeter diameter is equal to the pipe diameter View Answer Answer: c Explanation: None. 4. The Orificemeter readings are more accurate than Venturimeter. a) True b) False View Answer Answer: b Explanation: The Venturimeter readings are more accurate than Orificemeter. 5. The Orificemeter readings are more accurate than Pitot tube readings. a) True b) False View Answer Answer: b Explanation: The Pitot tube readings are more accurate than Orificemeter. 6. The Orificemeter has a smooth edge hole. a) True b) False View Answer Answer: b Explanation: The Orificemeter has a rough edge hole. 7. A Manometre is connected to a section which is at a distance of about 4 to 6 times the pipe diameter upstream from orifice plate. a) True b) False View Answer

Answer: b Explanation: A manometre is connected to a section which is at a distance of about 1.5 to 2.0 times the pipe diameter upstream from orifice plate.

8. Venturimeter is based on integral form of Euler’s equation. a) True b) False View Answer Answer: a Explanation: Venturimeter is based on Bernoulli’s equation. 9. Orifice Meter can only be used for measuring rate of flow in open pipe like structure. a) True b) False View Answer Answer: a Explanation: Orificemetre can only be used for measuring rate of flow in an enclosed pipe like structure. 10. Orifice meter consists of a flat rectangular plate. a) True b) False View Answer Answer: b Explanation: Orifice meter consists of a flat circular plate.

Hydraulic Machines – Centrifugal Pumps 1. Centrifugal pump is a_________ a) Turbomachinery b) Flow regulating device c) Drafting device d) Intercooling device View Answer Answer: a Explanation: Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer

energy between a rotor and a fluid, including both turbines and compressors. It is a mechanical device. 2. Turbomachines work under ________ a) Newtons first law b) Newtons second law c) Newtons third law d) Kepler’s law View Answer Answer: b Explanation: Turbomachines work under Newtons second law. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. It is a mechanical device. 3. The main function of nozzle is to __________ a) Varying temperatures b) Pressure variations c) Load variations d) Heat variations View Answer Answer: b Explanation: The main function of nozzle is to vary the pressure of fluid passing through the nozzle. It is done by opening and shutting the sets of nozzles. Thus, its main function is to regulate pressure of the fluid. 4. The main function of centrifugal pumps are to ________ a) Transfer speed b) Transfer pressure c) Transfer temperature d) Transfer energy View Answer Answer: d Explanation: The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. It is a mechanical device. 5. Centrifugal pumps transfer energy from _______ a) Rotor to fluid b) Fluid to rotor c) Draft to rotor d) Rotor to draft View Answer Answer: a Explanation: Centrifugal pumps transfer energy from rotor to fluid. The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery.

6. Which among the following control the flow rate? a) Valve b) Pump c) Head d) Tank pipe View Answer Answer: a Explanation: Flow rate of the tank is controlled by the valve. The actuation of individual valve closes. This corresponds to the set of nozzle thereby controlling the actual flow rate of the fluid passing through the valve. 7. Turbines and compressors work with the gas, while centrifugal pump transfers energy. a) True b) False View Answer Answer: a Explanation: Turbines and compressors work with the gas, while centrifugal pump transfers energy. Centrifugal pumps transfer energy from rotor to fluid. The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbo machinery. 8. The inlet passage of water entry is controlled by ________ a) Head race b) Gate c) Tail race d) Pump View Answer Answer: b Explanation: The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine. 9. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. a) True b) False View Answer Answer: a Explanation: The statement is true. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. The main function of centrifugal pumps are to transfer energy. 10. Centrifugal pumps are used to transport ________ a) Pressure b) Speed c) Power d) Fluid View Answer

Answer: d Explanation: Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. 11. Centrifugal pumps transport fluids by converting _________ a) Kinetic energy to hydrodynamic energy b) Hydrodynamic energy to kinetic energy c) Mechanical energy to kinetic energy d) Mechanical energy to Hydrodynamic energy View Answer Answer: a Explanation: Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. 12. With the increase in load, Energy in the turbine________ a) Decreases b) Increases c) Remains same d) Independent View Answer Answer: a Explanation: When there is an increase in the load, the energy in the turbine is drained off. Thus, to increase the energy, the by pass valve is opened to increase the amount of fresh steam entry. This increases the energy in the turbine.

13. The rotational kinetic energy comes from ______ a) Engine motor b) Pump c) Tank d) Draft tube View Answer Answer: a Explanation: Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. The rotational kinetic energy comes from engine or electrical motor. 14. When the balancing of the turbine is disturbed, we use ________ a) Throttle governing b) Steam governing c) Nozzle governing

d) Emergency governing View Answer Answer: d Explanation: When the balancing of the turbine is disturbed, we use emergency governing. These governors come into action only when there are emergencies in the turbine. 15. The fluid coming into the centrifugal pump is accelerated by ________ a) Throttle b) Impeller c) Nozzle d) Governor View Answer Answer: b Explanation: The fluid coming into the centrifugal pump is accelerated by an impeller. The fluid enters the pump along a radially outward direction into the diffuser or a volute chamber.

Main Parts of Centrifugal Pumps 1. A gear pump uses ___________ a) Petrochemical pumps b) Meshing of gears c) Froth pumps d) Airlift pumps View Answer Answer: b Explanation: A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations.

2. The fundamental significance of all the turbomachinery is _______ a) Conservation of momentum b) Conservation of mass c) Conservation of heat d) Conservation of speed View Answer Answer: a Explanation: The fundamental significance of all the turbomachinery is the conservation of momentum. It plays an important role in various turbomachinery. 3. The most common pump used for hydraulic fluid power application is __________ a) Centrifugal pumps b) Gear pump c) Froth pumps d) Airlift pumps View Answer Answer: b Explanation: The most common pump used for hydraulic fluid power application is gear pump. A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations. 4. The change of angular momentum in a pump is equal to the _________ a) Sum of speeds b) Sum of individual momentum c) Sum of temperatures d) Sum of energy transferred from a body View Answer Answer: b Explanation: The change of angular momentum in a pump is equal to the sum of individual momentum. 5. Conservation of angular momentum is described by _______ a) Newtons equation b) Euler’s equation c) Rutherford’s equation d) Maxim equation View Answer Answer: b Explanation: Conservation of angular momentum is described by Euler’s equation. It states that the change of angular momentum in a pump is equal to the sum of individual momentum. 6. Gear pumps are mainly used in chemical installations because they pump ________ a) High viscosity fluids b) High density fluids c) High pressure fluids

d) High temperature fluids View Answer Answer: a Explanation: Gear pumps are mainly used in chemical installations because they pump high viscosity fluids. They use two external spur gears for this purpose. 7. Gear pumps convert rotational kinetic energy to hydrodynamic energy. a) True b) False View Answer Answer: a Explanation: Gear pumps are used to transport fluids. They transport fluids by conversion of energies. Gear pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. 8. The inlet passage of centrifugal pump is controlled by ________ a) Gate b) Head race c) Turbine d) Pump View Answer Answer: a Explanation: The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine. 9. Absolute exit velocity in a pump is denoted as ______ a) c2 b) v2 c) p2 d) w2 View Answer Answer: a Explanation: Absolute exit velocity in a pump is denoted as ‘c2’. 10. Gear pumps are used to transport ________ a) Pressure b) Speed c) Power d) Fluid View Answer Answer: d Explanation: Gear pumps are used to transport fluids. They transport fluids by conversion of

energies. A gear pump uses meshing of gears. This meshing is done to pump fluid by displacement. Gear pumps are widely used in chemical installations. 11. Vertical Centrifugal pumps are also called as _________ a) Cantilever pumps b) Hydrodynamic pump c) Mechanical pump d) Hydroelectric pump View Answer Answer: a Explanation: Vertical Centrifugal pumps are also called as cantilever pumps. 12. With the increase in load, Energy in the turbine________ a) Decreases b) Increases c) Remains same d) Independent View Answer Answer: a Explanation: When there is an increase in the load, the energy in the turbine is drained off. Thus, to increase the energy, the by pass valve is opened to increase the amount of fresh steam entry. This increases the energy in the turbine. 13. The rotational kinetic energy comes from ______ a) Engine motor b) Pump c) Tank d) Draft tube View Answer Answer: a Explanation: Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. The rotational kinetic energy comes from engine or electrical motor. 14. When the balancing of the turbine is disturbed, we use ________ a) Throttle governing b) Steam governing c) Nozzle governing d) Emergency governing View Answer Answer: d Explanation: When the balancing of the turbine is disturbed, we use emergency governing. These governors come into action only when there are emergencies in the turbine.

15. Gear pumps are ___________ a) Tangential flow pumps b) Positive displacement pumps c) Negative displacement pumps d) Radial pumps View Answer Answer: a Explanation: Gear pumps are positive displacement pumps or fixed displacement pumps. This means that they pump at a constant amount of fluid each revolution.

Work done by Centrifugal Pump 1. The fluid gains _________ while passing through the impeller. a) Velocity b) Pressure c) Temperature d) Velocity and pressure View Answer Answer: d Explanation: The fluid gains both velocity and pressure while passing through the impeller. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. 2. What is the shape of the diffuser in the centrifugal pump? a) Round b) Dough nut c) Rectangle d) Cylindrical View Answer Answer: b Explanation: The shape of the diffuser passing present in the centrifugal pump is doughnut shaped. It is made into that shape as it allows the device to scroll up and down. Due to this, the casing decelerates the flow. 3. When the casing in a centrifugal pump decelerates the flow, what increases? a) Pressure b) Temperature c) Volume d) Flow rate View Answer Answer: a Explanation: When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped.

4. The velocity imparted by the impeller is converted into _________ a) Pressure energy b) Kinetic energy c) Momentum d) Potential energy View Answer Answer: a Explanation: The velocity imparted by the impeller is converted into pressure energy. It is in accordance with the Newtons second law. 5. The consequence of Newtons second law is_________ a) Conservation of angular momentum b) Conservation of mass c) Conservation of potential energy d) Conservation of kinetic energy View Answer Answer: a Explanation: The consequence of Newtons second law is the conservation of angular momentum. This, in accordance with newtons second law, provides the basic details to define parameters in the centrifugal pump. 6. Change of angular momentum is equal to ________ a) Sum of external moments b) Sum of their potential energies c) Sum of their kinetic energies d) Sum of their pressures View Answer

Answer: a Explanation: Change of angular momentum is equal to Sum of external moments. This is in accordance with Newton’s second law. The consequence of Newtons second law is the conservation of angular momentum. 7. Euler developed the head pressure equation in centrifugal pumps. a) True b) False View Answer Answer: a Explanation: Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. Euler developed the head pressure equation in centrifugal pumps. 8. What is a major advantage of centrifugal pump? a) Cost

b) Simple in construction c) Efficiency d) Pump parameters View Answer Answer: b Explanation: The major advantage of the centrifugal pump is that it has got a simple construction when compared to other types of centrifugal pumps. 9. ‘Ht’ means _______ a) Tangential head b) Horizontally head c) Theory head pressure d) Radially head pressure View Answer Answer: c Explanation: ‘Ht’ in the context of centrifugal pump means theory head pressure. It is used in a centrifugal pump equation that was derived by Euler. Euler developed the head pressure equation in centrifugal pumps. 10. Centrifugal pumps are used to transport ________ a) Pressure b) Speed c) Power d) Fluid View Answer Answer: d Explanation: Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. 11. Different velocities in a centrifugal pump are determined by using ________ a) Velocity triangle b) Reynolds number c) Froude number d) Overall efficiency View Answer Answer: a Explanation: Different velocities in a centrifugal pump are determined by using velocity triangle. This is an important triangle that determines the way the pump works. 12. Due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications. a) True b) False View Answer

Answer: a Explanation: Due to its impeller action, centrifugal pumps can cover a wide range of fluid pump applications. Thus, the impeller action plays an important role. 13. With the increase in the input power, efficiency _______ a) Increases b) Decreases c) Same d) Independent View Answer Answer: b Explanation: With the increase in the input power, efficiency decreases. As the input power is inversely proportional to the efficiency of the pump. 14. What is unit of standard acceleration? a) kg/m b) kg/s c) kg/m3 d) N/m View Answer Answer: c Explanation: The unit of standard acceleration of the centrifugal pump is kg/m3. It is denoted as g. It is also called as the acceleration due to gravity. 15. What does PSP stand for? a) Pump start procedure b) Positive start pump c) Pump start pointer d) Positive start pointer View Answer Answer: a Explanation: PSP stands for Pump start procedure. It is the basic method to start the pump by lining up the pump valves in a sequence by ensuring that the drain valve is closed.

Heads and Efficiencies in Centrifugal Pumps 1. What is the unit of flow rate? a) kg.m b) kg/m c) m3/s d) /s View Answer

Answer: c Explanation: The unit of flow rate in a centrifugal pump is m3/s. It is denoted as ‘Q’. It plays an important role to determine the efficiency of the pump. 2. With the increase in the flow rate, efficiency ______ a) Decreases b) Increases c) Remains same d) Independent View Answer Answer: b Explanation: With the increase in the flow rate, efficiency increases. The unit of flow rate in a centrifugal pump is m3/s. It is denoted as ‘Q’. It plays an important role to determine the efficiency of the pump. 3. Pump efficiency is defined as the ratio of ___________ a) Pressure to temperature b) Temperature to pressure c) Water horsepower to pump horsepower d) Pump horse power to water horse power View Answer Answer: c Explanation: Pump efficiency is defined as the ratio of water horsepower to the pump horsepower. The unit of flow rate in a centrifugal pump is m3/s. It is denoted as ‘Q’. It plays an important role to determine the efficiency of the pump. 4. The difference in the total head of the pump is called _______ a) Manometric head b) Euler head c) Pressure head d) Shaft head View Answer Answer: a Explanation: The difference in the total head of the pump is called manometric head. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. 5. The ratio of manometric head to the work head is called _______ a) Manometric head b) Euler head c) Pressure head d) Shaft head View Answer

Answer: b Explanation: The ratio of manometric head to the work head is called Euler head. It is also called as manometric efficiency. 6. What is the unit of energy head? a) m b) m/s c) m3/s d) /s View Answer Answer: a Explanation: The unit of energy head is meter. The energy head is denoted as ‘H’. It plays an important role to determine the efficiency of the pump. 7. With the increase in energy head, efficiency ________ a) Decreases b) Increases c) Remains same d) Independent View Answer Answer: b Explanation: With the increase in energy head, efficiency increases. Since energy is directly proportional to the efficiency of the turbine. The unit of energy head is meter. The energy head is denoted as ‘H’. It plays an important role to determine the efficiency of the pump. 8. The head added by the pump is a sum of _________ a) Pressure b) Static lift c) Volume d) Flow rate View Answer Answer: b Explanation: The head added by the pump is a sum of static lift. With the increase in energy head, efficiency increases. Since energy is directly proportional to the efficiency of the turbine. The unit of energy head is meter. The energy head is denoted as ‘H’. It plays an important role to determine the efficiency of the pump. 9. Power is most commonly expressed as ________ a) m b) kW c) m3/s d) /s View Answer

Answer: b Explanation: Power is most commonly expressed as kilo watts. One kilo watts is equal to 0.746 horse power. It plays an important role in determining the efficiency of the turbine. 10. PHE stands for __________ a) Pump Hydraulic efficiency b) Pressure Hydraulic efficiency c) Power Hydraulic efficiency d) Pump hydraulic engine View Answer Answer: a Explanation: PHE stands for Pump hydraulic efficiency. Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. 11. Vertical centrifugal pumps are also called as cantilever pumps. a) True b) False View Answer Answer: a Explanation: Vertical centrifugal pumps are also called as cantilever pumps. Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery. 12. With increase in power, the efficiency_________ a) Decreases b) Increases c) Remains same d) Independent View Answer Answer: a Explanation: With the increase in the input power, efficiency decreases. As the input power is inversely proportional to the efficiency of the pump.

13. Vertical pumps utilize unique shaft and bearing support configuration. a) True b) False View Answer Answer: a Explanation: Vertical pumps utilize unique shaft and bearing support configuration. It allows them to hang in the sump while the bearings are outside the sump. Thus, it is a true.

14. Which among the following is used in mineral industries? a) Vertical pumps b) Horizontal pumps c) Froth pumps d) Multistage pumps View Answer Answer: c Explanation: In the mineral industries, we use froth pumps to extract oil sand. Froth is generated to separate rich minerals.

Minimum Speed for Starting Centrifugal Pump 1. Vertical centrifugal pumps are also called as ________ a) Froth pumps b) Multistage pumps c) Cantilever pumps d) Magnetic pumps View Answer Answer: c Explanation: Vertical centrifugal pumps are also called as cantilever pumps. They utilize a unique shaft and bearing support for configuration. Thus, it is called as cantilever pumps.

2. Vertical pump uses _______ a) Draft tube b) Throttle bush c) Stuffing box d) Interlining View Answer Answer: b Explanation: Vertical pumps use throttle bush. They do not use stuffing box. Vertical centrifugal pumps are also called as cantilever pumps. They utilize a unique shaft and bearing support for configuration. Thus, it is called as cantilever pumps.

3. When the casing in a centrifugal pump decelerates the flow, what increases? a) Pressure b) Temperature c) Volume d) Flow rate View Answer Answer: a Explanation: When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped.

4. The maximum volumetric efficiency of a pump(100cc) is ________ a) 60% b) 70% c) 80% d) 90% View Answer Answer: d Explanation: The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. It is a mechanical device.

5. The most common application of vertical centrifugal pump is used in _______ a) Parts washer b) Mineral industry c) Paper plating d) Jukebox View Answer Answer: a Explanation: The most application of the vertical centrifugal pump is used in parts washer. Vertical pumps use throttle bush. They do not use stuffing box. Vertical centrifugal pumps are also called as cantilever pumps.

6. What does BEP stand for? a) Best efficiency point b) Brake ejection point c) Break effect point d) Best effect point View Answer Answer: a Explanation: BEP stands for Best efficient point. It is a point at which Shut off and Run out point. It helps to identify the pumps performance.

7. The height of a column in a pump is called as _______ a) Vertical head b) Horizontal head c) Static head d) Multi head View Answer Answer: c Explanation: In a centrifugal pump, the height of the column is called as a static head. Static head corresponds to the pressure depending on the weight.

8. The centrifugal pump has varying flow depending on the _________ a) Pressure b) Static lift

c) Volume d) Flow rate View Answer Answer: a Explanation: Due to pressure variations there are changes that take place in the centrifugal pump. Thus, the flow keeps varying.

9. What is purpose of froth in froth pumps? a) Separates rich minerals b) Mixes rich minerals c) Removes ores d) Detects oil View Answer Answer: a Explanation: The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

10. Froth contains air that blocks the pumps. a) True b) False View Answer Answer: a Explanation: Froth contains air that blocks the pumps. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

11. When froth blocks the pump, it leads to _______ a) Separation of rich minerals b) Mixing of rich minerals c) Removing of ores d) Loss of prime View Answer Answer: d Explanation: When froth blocks the pump, it leads to loss of prime. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

12. What affects volumetric efficiency of the pump? a) Complex interactions b) Internal interactions c) Retain flow d) Air flow View Answer Answer: a Explanation: The volumetric efficiency of the centrifugal is affected due to complex interactions. Thus, some engines use two intake manifolds.

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13. The Positive Displacement Pump has more or less a constant flow regardless of the system pressure or head. a) True b) False View Answer Answer: a Explanation: The Positive Displacement Pump has more or less a constant flow regardless of the system pressure or head.

14. What is the purpose of inducer in a froth pump? a) It recirculates air b) The pressurizes the air c) Froths are generated d) It breaks the bubbles View Answer Answer: d Explanation: The purpose of the inducer in a froth pump is to break the bubbles. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays

Hydraulic Machines Questions and Answers – Multistage Centrifugal Pumps for High Heads This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Multistage Centrifugal Pumps for High Heads”. 1. A multistage centrifugal pumps has more than two _______ a) Pumps b) Impellers c) Turbines d) Magnetic pumps View Answer Answer: b Explanation: A multistage centrifugal pumps has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 2. The impeller is mounted on a ________ a) Draft tube b) Throttle bush c) Stuffing box

d) Shaft View Answer Answer: d Explanation: The impeller is mounted on one shaft or different shaft. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 3. At each stage the fluid is directed ________ a) Towards the centre b) Away the centre c) Towards the surface d) Away from the centre View Answer Answer: a Explanation: At each stage in the centrifugal pump, the fluid is directed to towards the centre. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 4. If the cylinder is filled with fuel or air it is said to be ___________ a) 100% efficient b) Transfer efficient c) Nil efficient d) Flow effective View Answer Answer: a Explanation: If the cylinder is filled with fuel or air, it is said to be 100 percent efficient. It plays a major role in regulating the flow of fluid. 5. SOH in a pump stands for_______ a) Shut Off head b) Shut off heat c) Shut off hybrid d) Set off head View Answer Answer: a Explanation: SOH in a pump stands for Shut OFF head. The shut off head is located at the maximum head of the pipe. 6. At higher pressures, the impeller is connected in _______ a) Series b) Parallel c) Equilibrium d) Series and parallel View Answer

Answer: a Explanation: At higher pressures, the impeller is connected in series. The impeller is mounted on one shaft or different shaft. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 7. When the flow output is higher, impellers are connected in________ a) Series b) Parallel c) Equilibrium d) Series and parallel View Answer Answer: b Explanation: When the flow output is higher, impellers are connected in parallel. The impeller is mounted on one shaft or different shaft. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 8. The point at which piping system controls the flow rate is called ______ a) Pressure point b) Static lift c) Operating point d) Flow point View Answer Answer: c Explanation: The point at which piping system controls the flow rate is called operating point of the pump. It plays a major role in controlling the piping system before regulation. 9. What is the common application of multistage centrifugal pump? a) Mineral industries b) Boiler feed water pump c) Removes ores d) Detects oil View Answer Answer: b Explanation: The most common application of multistage centrifugal pump is boiler feed water pump. 10. A multistage centrifugal pump produces a pressure of __________ a) 10 Pa b) 100 MPa c) 21 MPa d) 150 MPa View Answer Answer: c Explanation: A multistage centrifugal pump produces a pressure of 21 MPa. A multistage

centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 11. All energy that is transferred from the fluid is derived from ________ a) Electrical energy b) Mechanical energy c) Thermal energy d) Chemical energy View Answer Answer: b Explanation: All energy that is transferred from the fluid is derived from Mechanical energy. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 12. The point at which the centrifugal pump operates at maximum efficiency is called _______ a) Duty point b) Flow point c) Static point d) Operating point View Answer Answer: a Explanation: The point at which the centrifugal pump operates at maximum efficiency is called duty point. It is determined by the flow rate of the pump. advertisement

13. The energy transferred can be measured by isentropic compression. a) True b) False View Answer Answer: a Explanation: The energy transferred in a centrifugal pump can be measured by isentropic compression. The multistage centrifugal is similar to the centrifugal pumps working. 14. What does TDH stand for? a) Total dynamic head b) Total depth head c) Tight drum head d) Target dynamic head View Answer Answer: a Explanation: TDH stands for total dynamic head. It is total height at which fluid is to be pumped for maximum effiency.

15. The mechanical energy is developed by the impeller.

Hydraulic Machines Questions and Answers – Multistage Centrifugal Pumps for High Discharge This set of Hydraulic Machines Multiple Choice Questions & Answers focuses on “Multistage Centrifugal Pumps for High Discharge”. 1. The mechanical energy can be measured by ______ a) Adiabatic expansion b) Isentropic compression c) Adiabatic compression d) Isentropic expansion View Answer Answer: b Explanation: The mechanical energy in a centrifugal pump that is driven by the impeller mounted on a shaft is measured by isentropic compression. Thus, the correct choice is isentropic compression. 2. How many impellers does a multistage centrifugal pump have? a) Zero b) One c) Exactly two d) Two and more View Answer Answer: d Explanation: The centrifugal pump consists of two or more impellers. The impeller is mounted on one shaft or different shaft. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working. 3. The energy usage in pumping installation is determined by _______ a) Friction characteristics b) Pipe diameter c) Surface tension d) Thermal expansion View Answer Answer: a Explanation: At each stage in the centrifugal pump, the fluid is directed to towards the centre. The energy usage in pumping installation is determined by Friction characteristics. Thus, it is the most suitable option. 4. Which among the following is a friction factor? a) Newtons factor

b) Darcy’s factor c) Transfer temperature d) Heizenberg’s factor View Answer Answer: b Explanation: From the above, the factor that involves friction is determined by Darcy’s friction factor. The energy usage in pumping installation is determined by Friction characteristics. Thus, it is used in energy calculations in a pump. 5. What is the dimension for Darcy’s friction factor? a) kg/m b) N/mm c) kg d) Dimensionless View Answer Answer: d Explanation: Darcy’s friction factor is dimensionless. It is one of the major applications in Fluid dynamics. The energy usage in pumping installation is determined by Friction characteristics. Thus, it is dimensionless. 6. Formation of bubbles in an impeller is called ______ a) Cavities b) Defects c) Friction d) Heat burn View Answer Answer: a Explanation: Formation of bubbles in an impeller is called as its as its cavities. These cavities develop intense shockwaves in the impeller. 7. Centrifugal pump works by imparting _______ a) Potential energy b) Kinetic energy c) Heat energy d) Electrical energy View Answer Answer: b Explanation: Centrifugal pump works by imparting kinetic energy to the liquid for rotating the impeller rotor. 8. What is the full form of NPSH in a pump? a) Net pressure suction head b) Net positive suction head c) Non-pressure suction head

d) Net pressure super head View Answer Answer: b Explanation: The full form of NPSH is Net positive suction head. The head added by the pump is a sum of static lift. Thus, corresponds to the efficient working of the pump. Higher the NPSH, more efficient the pump is. 9. When the NPSH is low, it leads to ________ a) Breaking b) Wear c) Corrosion d) Cavitation View Answer Answer: d Explanation: When the NPSH is low, it leads to cavitation. Cavitation is one of the major drawbacks that are seen in a centrifugal pump. There are various other problems as well. But, cavitation is due to low NPSH. 10. Wear of impeller can be worsened by __________ a) Draft tube b) Pump pressure c) Suspended solenoids d) Turbine head View Answer Answer: c Explanation: Wear of impeller can be worsened by suspended solenoids. Wear and tear is one of the major drawbacks that are seen in a centrifugal pump. It affects the working of the impeller, thus resulting in an inefficient working. 11. Which pump is the most efficient centrifugal pump? a) Electrical pump b) Reciprocating pump c) Heat pump d) Pressure pump View Answer Answer: b Explanation: Reciprocating pump is the most efficient centrifugal pump because as the pressure increases, the flow rate remains constant. 12. Corrosion in the pump is developed due to _______ a) Pressure of air b) Fluid properties c) Draft tube d) Tank dimensions View Answer

Answer: b Explanation: Corrosion in the pump is developed due to fluid properties. The flow of fluid plays a major role in determining the corrosion developed. Fluid flow can broadly be classified into laminar and turbulent depending on its Reynolds number. advertisement

13. Over heating is a major problem faced in a pump. a) True b) False View Answer Answer: a Explanation: Over heating is a major problem faced in a pump. The temperature in a centrifugal pump is increases mainly due to the presence of low flow. Thus, by heating the fluid, the velocity of fluid flow increases. 14. What is the effect of cavitation in boat propeller? a) It recirculates air b) The pressurizes the air c) It leads to fast spinning d) It breaks the bubbles View Answer Answer: c Explanation: Cavitation in a boat propeller or a ship propeller leads to fast spinning due to the formation of bubbles. 15. Lack of prime is a problem faced in centrifugal pump. a) True b) False View Answer Answer: a Explanation: Yes, Lack of prime is a problem faced in centrifugal pump. It means that the centrifugal pump must be filled in order to operate in an effective way. The fluid must be filled in such a way so that it can pump

Hydraulic Machines Questions and Answers – Specific Speed Centrifugal Pumps This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Specific Speed Centrifugal Pumps”. 1. The energy usage of a pump is determined by _______ a) Adiabatic expansion b) Power required c) Adiabatic compression

d) Isentropic expansion View Answer Answer: b Explanation: The energy usage of a pump is determined by power required. Thus, it plays an important role in determining the amount of energy that a pump dissipates during its operation. It is with respect to the length of time. 2. For an oil field to have solid control, it needs _______ a) Draft tubes b) Throttle bush c) Stuffing box d) Centrifugal pumps View Answer Answer: d Explanation: For an oil field to have solid control, it needs centrifugal pumps. At each stage in the centrifugal pump, the fluid is directed to towards the centre. This makes it more efficient in operating a large oil field. 3. If we lower the temperature, the water pump cavitation ________ a) Increases b) Decreases c) Same d) Independent View Answer Answer: b Explanation: If we lower the temperature, the water pump cavitation decreases. This happens as the NPSH value reaches a safety margin. 4. Which among the following is not a centrifugal pump? a) Sand pumps b) Froth pumps c) Slurry pumps d) Energy pumps View Answer Answer: d Explanation: From the above, Energy pumps are not a type of centrifugal pump. At each stage in the centrifugal pump, the fluid is directed to towards the centre. The energy usage in pumping installation is determined by Friction characteristics. Thus, it is not a suitable option. 5. Centrifugal pumps work under the same principle, but differ in their _______ a) Working b) Functions c) Dimensions d) Impeller View Answer

Answer: b Explanation: Centrifugal pumps work under the same principle, but differ in their functions. At each stage in the centrifugal pump, the fluid is directed to towards the centre. The energy usage in pumping installation is determined by Friction characteristics. 6. If we raise the liquid level in the suction vessel, cavitation ______ a) Increases b) Decreases c) Same d) Independent View Answer Answer: b Explanation: If we raise the liquid level in the suction vessel, cavitation decreases. This happens as the NPSH value reaches a safety margin. 7. Magnetic coupled pumps are also called as _________ a) Series pumps b) Parallel pumps c) Froth pumps d) Drive pumps View Answer Answer: d Explanation: Magnetic coupled pumps are also called a magnetic drive pumps. They show a lot of difference in their traditional pumping style. It is connected by means of direct mechanical shaft. 8. Magnetic coupled pumps works via ________ a) Antiferromagnet b) Drive magnet c) Pump magnet d) Ferromagnet View Answer Answer: b Explanation: Magnetic coupled pumps works via drive magnet. Magnetic coupled pumps are also called a magnetic drive pumps. They show a lot of difference in their traditional pumping style. It is connected by means of direct mechanical shaft. 9. When we change the pump, the cavitation ______ a) Increases b) Decreases c) Same d) Independent View Answer

Answer: b Explanation: By changing the pump we can decrease the cavitation in the pump by bringing the NPSH value to a safety margin. 10. If we reduce the motor rpm in an impeller, cavitation _______ a) Increases b) Decreases c) Same d) Independent View Answer Answer: b Explanation: If we reduce the motor rpm in an impeller, cavitation decreases. This can be done by setting the NPSH value in the safety limit. 11. Decreasing the diameter of the eye of the impeller, cavitation _________ a) Increases b) Decreases c) Same d) Independent View Answer Answer: a Explanation: Decreasing the diameter of the eye of the impeller, cavitation increases due to deviation from the safety limit. 12. No gland is needed for the centrifugal pump. a) True b) False View Answer Answer: a Explanation: No gland is needed for the centrifugal pump. This is because they have no direct connection between the motor shaft and the impeller, so there is not a requirement of gland in pumps. advertisement

13. Pump is always supported by bearings. a) True b) False View Answer Answer: b Explanation: Pump shaft is not always supported by bearings. Since the pumps have no bearing support. The pumps are provided with a housing. The inner walls of the pump are provided with bushings. 14. If we use an impeller inducer, we can reduce the cavitation in a centrifugal pump. a) True

b) False View Answer Answer: a Explanation: Yes, If we use an impeller inducer, we can reduce the cavitation in a centrifugal pump by bringing the NPSH value to a safety limit. 15. There will be leakage only if there is ________ a) High pressure b) High temperature c) Froths are generated d) Casing breakage View Answer Answer: d Explanation: Pumps have a major problem called as leakage. This might lead to a lot of losses during product manufacture. Thus, the leakage is mainly due to the breaking of the case. Thus, the correct option is casing breakage.

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Priming Centrifugal Pumps 1. When a pump casing is filled with liquid before it is started, it is called as _________ a) Adiabatic expansion b) Priming c) Adiabatic compression d) Isentropic expansion View Answer

Answer: b Explanation: When a pump casing is filled with liquid before it is started, it is called as priming. Most of the centrifugal pumps are not self priming. At this stage, the pump will not be able to function.

2. The pump will become incapable of pumping in case of _______ a) Gas bounding b) Throttle bush c) Stuffing box d) Casing breakage View Answer Answer: d Explanation: For an oil field to have solid control, it needs centrifugal pumps. At each stage in the centrifugal pump, the fluid is directed to towards the centre. This makes it more efficient in operating a large oil field.

3. Priming is needed when impeller cannot impart enough _________ a) Draft speed b) Energy c) Pressure d) Heat View Answer Answer: b Explanation: Priming is needed when impeller cannot impart enough energy. Therefore priming is compulsory in this case.

4. Priming performs response using ________ a) Stimulus b) Froth c) Slurry d) Heat View Answer Answer: a Explanation: Priming performs response using a stimulus. It is an implicit method in which exposure to flow of fluid takes place.

5. To avoid gas bounding, the pump is _________ a) Heated b) Elevated c) Primed d) Charged View Answer Answer: c Explanation: Centrifugal pumps work under the same principle, but differ in their functions. At each stage in the centrifugal pump, the fluid is directed to towards the centre. To avoid gas bounding, the pump is primed.

6. Centrifugal pumps are located ________ the level of source a) Below b) Above c) Parallel with d) Series with View Answer Answer: a Explanation: Centrifugal pumps are located below the level of source. It is located in such way because, it takes away the suction at a faster rate.

7. A pump that can evacuate air is called as _________ a) Series pumps b) Self priming pumps c) Froth pumps d) Drive pumps View Answer Answer: b Explanation: A pump that can evacuate air is called as self priming pumps. In normal conditions, it is difficult for centrifugal pumps to evacuate the air from the inlet line leading to a fluid level to a different altitude.

8. What does CPO stand for? a) Centrifugal pump operation b) Centrifugal part operation c) Centrifugal pump output d) Centrifugal part output View Answer Answer: a Explanation: CPO stands for centrifugal pump operation. It has got a pump start off procedure and pump shut down procedure.

9. Self priming pumps overshadow the function of __________ a) Self auxiliary device b) Wear rate c) Corrosion device d) Cavitation device View Answer Answer: a Explanation: Self priming pumps overshadow the function of self auxiliary device. A pump that can evacuate air is called as self priming pumps. In normal conditions, it is difficult for centrifugal pumps to evacuate the air from the inlet line leading to a fluid level to a different altitude.

10. What is necessary for self priming to take place? a) Draft tube b) Pump casing

c) Suspended solenoids d) Turbine head View Answer Answer: b Explanation: For self priming to take place, pump casing is necessary. This helps to evacuate air in normal conditions.

11. Centrifugal pumps with an internal suction stage are called as _________ a) Series pumps b) Self priming pumps c) Froth pumps d) Drive pumps View Answer Answer: b Explanation: Centrifugal pumps with an internal suction stage are called as self priming pumps. A pump that can evacuate air is called as self priming pumps. In normal conditions, it is difficult for centrifugal pumps to evacuate the air from the inlet line leading to a fluid level to a different altitude.

12. Two phase mixture is pumped unit the suction line is evacuated. a) True b) False View Answer Answer: a Explanation: Two phase mixture is pumped unit the suction line is evacuated as the pump operates without a foot valve and without an evacuation device on the suction side. The pump has to be primed for this purpose.

13. During normal working operation, the pump works like __________ a) Centrifugal pumps b) Self priming pumps c) Froth pumps d) Drive pumps View Answer Answer: a Explanation: Pump shaft is not always supported by bearings. Since the pumps have no bearing support. The pumps are provided with a housing. During normal working operation, the pump works like centrifugal pumps.

14. The pump function that works on rinsing is called as dialysis of pump. a) True b) False View Answer Answer: a Explanation: Yes, The pump function that works on rinsing is called as dialysis of pump.

15. What is purpose of vent valve in a pump? a) High pressure control b) High temperature control c) Froths are generated can be minimized d) To prevent siphon action View Answer Answer: d Explanation: The main function of a suction swindle valve or vent valve in a centrifugal pump is to prevent any siphon action and ensure that the fluid remains in the casing when the pump has been stopped.

Net Positive Suction Head – NPSH 1. In hydraulic head, NPSH is used for the analysis of __________ a) Adiabatic expansion b) Priming c) Wear d) Cavitation View Answer

Answer: d Explanation: In hydraulic head, net positive circuit is used for the analysis of cavitation. It determines the cavitation present in the centrifugal pump by different methods. 2. NPSH is the difference between _______ a) Suction pressure and vapour pressure b) Vapour pressure and suction pressure c) Suction pressure and heat d) Shaft and head View Answer Answer: a Explanation: NPSH is defined as the difference suction pressure and vapour pressure. It is called as the net positive suction head. 3. What can NPSH be used to determine _______ a) Friction characteristics b) Pipe diameter c) Cavitation d) Thermal expansion View Answer Answer: c Explanation: NPSH is used to determine the cavitation in pumps. NPSH is defined as the difference suction pressure and vapour pressure. It is called as the net positive suction head. 4. The measure of how close the fluid is to the given point is called _________ a) Flashing b) Darcy’s factor c) Transfer temperature d) Heizenberg’s factor View Answer Answer: a Explanation: The measure of how close the fluid is to the given point is called flashing. It is one of the major methods in the NPSH to determine the cavitation. 5. What is the dimension for Darcy’s friction factor? a) kg/m b) N/mm c) kg d) Dimensionless View Answer Answer: d Explanation: Darcy’s friction factor is dimensionless. It is one of the major applications in Fluid dynamics. The energy usage in pumping installation is determined by Friction characteristics. Thus, it is dimensionless.

6. NPSH is relevant ________ a) Outside the pumps b) Inside the pumps c) Away from the pumps d) Series and parallel with the pumps View Answer Answer: a Explanation: NPSH is relevant inside the pumps. hydraulic head, net positive circuit is used for the analysis of cavitation. It determines the cavitation present in the centrifugal pump by different methods. 7. With the increase in cavitation, the drag coefficient of the impeller ______ a) Increases b) Decreases c) Same d) Independent View Answer Answer: a Explanation: With the increase in cavitation, the drag coefficient of the impeller increases. When the flow output is higher, impellers are connected in parallel. The impeller is mounted on one shaft or different shaft. 8. What is the full form of NPSH in a pump? a) Net pressure suction head b) Net positive suction head c) Non-pressure suction head d) Net pressure super head View Answer Answer: b Explanation: The full form of NPSH is Net positive suction head. The head added by the pump is a sum of static lift. Thus, corresponds to the efficient working of the pump. Higher the NPSH, more efficient the pump is. 9. When the NPSH is low, it leads to ________ a) Breaking b) Wear c) Corrosion d) Cavitation View Answer Answer: d Explanation: When the NPSH is low, it leads to cavitation. Cavitation is one of the major drawbacks that are seen in a centrifugal pump. There are various other problems as well. But, cavitation is due to low NPSH.

10. What is positive suction head? a) Draft tube is above b) Pump pressure is above c) Liquid level is above d) Turbine head is above View Answer Answer: c Explanation: Positive suction head is defined as the point in which the liquid level is above the centre line of the pump. 11. NPSHr is determined by using ______ a) Pump pressure b) PumpLinx c) Heat transfer d) Chemical energy View Answer Answer: b Explanation: NPSHr of a pump can be determined by using Pumplinx. The full form of NPSH is Net positive suction head. The head added by the pump is a sum of static lift. 12. Corrosion in the pump is developed due to _______ a) Pressure of air b) Fluid properties c) Draft tube d) Tank dimensions View Answer Answer: b Explanation: Corrosion in the pump is developed due to fluid properties. The flow of fluid plays a major role in determining the corrosion developed. Fluid flow can broadly be classified into laminar and turbulent depending on its Reynolds number. 13. Calculation of NPSH in a turbine is different from the calculation of NPSH in a pump. a) True b) False View Answer Answer: a Explanation: Calculation of NPSH in a turbine is different from the calculation of NPSH in a pump. It is mainly because the point at which the cavitation will first occur is in a different place. 14. If we use two lower capacity pumps in parallel, cavitation ________ a) Increases b) Decreases c) Same d) Independent View Answer

Answer: b Explanation: If we use two lower capacity pumps in parallel, cavitation decreases. It happens when the NPSh value is bought in its safety limit. 15. Vapour pressure is strongly dependent on temperature in a pump. a) True b) False View Answer Answer: a Explanation: Yes, Vapour pressure is strongly dependent on temperature in a pump. It will thus increase the net positive suction head of the centrifugal pump

Hydraulic Machines Questions and Answers – Main Characteristic Curves This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Main Characteristic Curves”. 1. The characteristic curves of a centrifugal pump, plots ______ required by the pump. a) Velocity b) Pressure c) NPSH d) Velocity and pressure View Answer Answer: c Explanation: The characteristic curves of a centrifugal pump, plots net positive suction head required by the pump. These curves play an important role in determining the efficiency of a centrifugal pump. 2. What is the shape of the diffuser in the centrifugal pump? a) Round b) Dough nut c) Rectangle d) Cylindrical View Answer Answer: b Explanation: The shape of the diffuser passing present in the centrifugal pump is doughnut shaped. It is made into that shape as it allows the device to scroll up and down. Due to this, the casing decelerates the flow. 3. When the casing in a centrifugal pump decelerates the flow, what increases? a) Pressure b) Temperature

c) Volume d) Flow rate View Answer Answer: a Explanation: When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped. 4. Which among the following is not a characteristic curve for centrifugal pump? a) Transfer speed vs Transfer pressure b) Head vs Flow rate c) Power input vs pump efficiency d) Specific speed vs pump efficiency View Answer Answer: a Explanation: The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery. Transfer speed vs Transfer pressure is not considered as a correct characteristic curve. 5. The consequence of Newtons second law is _________ a) Conservation of angular momentum b) Conservation of mass c) Conservation of potential energy d) Conservation of kinetic energy View Answer Answer: a Explanation: The consequence of Newtons second law is the conservation of angular momentum. This, in accordance with newtons second law, provides the basic details to define parameters in the centrifugal pump. 6. Which of the following is taken into account during a characteristic curve? a) Flow rate b) Cavitation c) Tolerances d) Casing View Answer Answer: a Explanation: Flow rate is an important parameter that is taken into account for a characteristic curve. These curves play an important role in determining the efficiency of a centrifugal pump. 7. The normal operating range of centrifugal pump is sufficient to plot the characteristic curve. a) True b) False View Answer

Answer: a Explanation: The normal operating range of centrifugal pump is sufficient to plot the characteristic curve. Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. 8. The inlet passage of water entry is controlled by ________ a) Head race b) Gate c) Tail race d) Pump View Answer Answer: b Explanation: The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine. 9. As the specific speed increases, the slope of HQ curve _______ a) Decreases b) Increases c) Independent d) Remains the same View Answer Answer: c Explanation: As the specific speed increases, the slope of HQ curve increases. It becomes steeper with the corresponding increase in the specific speed. 10. The primary selection tool is called as _______ a) Pump curve b) Speed curve c) Power curve d) Fluid curve View Answer Answer: a Explanation: The primary selection tool is called as pump curve. It plays an essential role in determining efficiency. 11. In case of centrifugal turbines with low specific speed, the efficiency curve is _________ a) Pointed b) Small c) Steep d) Flat View Answer Answer: d Explanation: In case of centrifugal turbines with low specific speed, the efficiency curve is

relatively flat in the vertex. These curves play an essential role in determining the overall performance of the turbine. 12. In case of centrifugal turbines with high specific speed, the efficiency curve is a) Pointed b) Small c) Steep d) Flat View Answer Answer: a Explanation: In case of centrifugal turbines with high specific speed, the efficiency curve is relatively pointed in the vertex. These curves play an essential role in determining the overall performance of the turbine. advertisement

13. With the increase in the input power, efficiency _______ a) Increases b) Decreases c) Same d) Independent View Answer Answer: b Explanation: With the increase in the input power, efficiency decreases. As the input power is inversely proportional to the efficiency of the pump. 14. What is unit of standard acceleration? a) kg/m b) kg/s c) kg/m3 d) N/m View Answer Answer: c Explanation: The unit of standard acceleration of the centrifugal pump is kg/m3. It is denoted as g. It is also called as the acceleration due to gravity. Thus, the correct option is ‘c’