Geas

CNS: GEAS 2 1. Which of the following radiations will produce electron with highest energy? A. Visible Light C. X-rays B. Ultraviolet light D. Gamma rays ANSWER: Gamma Rays

A. 22.23 mm C. 33.33 mm* C. 23.44 mm D. 42.55 mm SOLUTION:

S

2. Two twins are 25 years old when one of them sets out on a journey through space at nearly constant speed. The twin in the spaceship measures time with an accurate watch. When he returns to earth, he claims to be 31 years old, while the twin left is then 43 years old. What was the speed of the spaceship? A. 3.83x108 m/s C. 2.8383x108 m/s B. 1.5683x108 m/s D. 4.5383x108 m/s SOLUTION: The spaceship clock reads the trip to be only 6 years long, while the earth clock reads it to be 18 years. Then using time dilation formula:

;

ts

 v   c

 r100 2   400   4  

P = 1,000,000r N From shearing of plate:

As  rDt  100rt

P  AsSs

1,000,000π  100π0300 t  33.33mm

ANSWER: 33.33 mm

= time moving clock

9. A cylindrical pressure vessel is fabricated from steel plates which have thickness of 20 mm. The diameter of the pressure vessel is 500 mm and its length is 3 m. Determine the maximum internal pressure which can be applied if the stress in the steel is limited to 140 MPa. A. 12.4 MPa C. 11.2 MPa B. 15.6 MPa D. 17.9 MPa

= time of stationary clock

6  18 1  

v v

tm ;

2

= 0.943c

SOLUTION:

= 2.83x108 m/s

F  ρDL  ρ 500 3000 F  1,500,000ρN

ANSWER: 2.83x108 m/s 3. The flow of heat from a hot to a cold body is an example of A. adiabatic process C. reversible process B. irreversible process D. isothermal process ANSWER: irreversible process

2T  F  1,500,000ρ T  750,000ρ P S A 750,000ρ 140  20 300 ρ  11.2MPa

4. How fast is an object moving if its apparent mass is to be 1 percent larger than its rest mass. A. 4.2x107 m/s C. 5.2x107 m/s B. 2.2x107 m/s D. 3.2x107 m/s SOLUTION:

 v   c

1 Solving gives

v

 mo    m 



2



mo     1.01m o 

 

ANSWER: 11.2 MPa

mo

m We make use of the formula

2

 Stress

P  AS  

2

 v t m  ts 1     c

P A

 v 1   c

2

to obtain

10. Compute the apparent mass of an electron traveling at half the speed of light. A. 1.05x10-30 kg C. 2.05 x10-30 kg B. 1.50 x10-30 kg D. 2.50 x10-30 kg SOLUTION: The rest mass of an electron is 9.1 x10-31 kg. Then

2  0.9803

= 0.14c = 4.2x10 m/s 7

ANSWER: 4.2x107 m/s 5. A heat engine with 100% of efficiency would have to A. do no work C. use no heat B. be at a uniform temperature D. discharge at 0ºC ANSWER: discharge at 0ºC 6. The process in which no heat enters or leaves the system is termed as A. isochoric C. isothermal B. isobaric D. adiabatic ANSWER: adiabatic 7. Two reversible engines A and B have their sources at 800 and 640K. Their sinks are at 400K and 300K respectively A. A is more efficient than B B. A is less efficient than B C. They are equally efficient D. Their efficiencies depend only upon the type of fuels used ANSWER: A is less efficient than B 8. A hole is to be punched out of a plate having an ultimate shearing stress of 300MPa. If the compressive stress in the punch is limited to 400MPa. Determine the maximum thickness of plate from a hole 100mm in diameter can be punched.

m

mo  v   c

1

2

mo



 0.5c    c 

1

2



mo 1  0.5

2



9.1  10-31kg 0.866

m  1.05  1031kg ANSWER: 1.05x10-30 kg 11. Compute the speed of sound in neon gas at 27ºC. For neon, N=20.18kg/kmol. A. 293 m/s C. 454 m/s B. 156 m/s D. 544 m/s SOLUTION: Neon being monoatomic gas, has Thus,

v

γRT  M

  1.67

1.678314J/kmolK300K 20.18kg/kmol

v  454m/s ANSWER: 454 m/s 12. The volume strain for a constqatn applied force increases directly with an increase in A. volume C. surface area

B. compressibility ANSWER: compressibility

D. bulk modulus

13. An explosion occurs at a distance of 6.0 km from a person. How long after the esplosion does the person hear it? Assume the temperature is 14ºC. A. 12.6 s C. 17.6 s B. 21.5 s D. 10.7 s SOLUTION: Because the speed of sound increases by 0.61 m/s for each ºC rise in temperature, we have v = 331 m/s + 0.61(14) v = 640 m/s Using s = vt, we find that the time taken is

s 6000m t   17.6s v 340s

ANSWER: 17.6 s

14. A property of matter that is often used by chemis as an “identification tag” for s asubstance. A. mass C. volume B. specific gravity D. density ANSWER: density 15. The mass of an alpha α particle is how many times more than that of the electron? A. 3500 times C. 1400 times B. 7300 times D. 6300 times ANSWER: 7300 times 16. What kind of chemical bond will form in binary compounds where the electronegativity difference between atoms is greater than 2.0? A. metallic bond C. ionic bond C. covalent bon D. mechanical bond ANSWER: Ionic Bond 17. What kind of chemical bond will form in binary compounds where the electronegativity difference between atoms is less than 1.5? A. metallic bond C. ionic bond B. covalent bond D. mechanical bond ANSWER: Covalent Bond 18. If the indeterminate error in weighing on a laboratory balance is 0.003 g. What size sample should you take to keep the relative error to 1.0%? A. 0.03 g C. 0.30 g B. 1.30 g D. 2.03 g ANSWER: 0.30 g of sample SOLUTION:

1.0% Relative error 

1 part in weight  100% total parts in weight

1 0.0030 g  100 X g of sample X  0.30 g of sample 19. What type of stress is produced whenever the applied load cause one section of a body to tend to slide past its adjacent section? A. normal stress C. sliding stress B. shearing stress* D. bearing stress ANSWER: shearing stress 20. The actual stress that the material has when under load is called: A. allowable stress C. working stress B. proportional limit D. rupture stress ANSWER: working stress 21. What type of deformation is caused by shearing stress? A. change in area C. change in shape B. change in volume D. angular change ANSWER: change in shape 22. The straight-line portion of stress-strain is actually a measure of ______ of the material. A. elasticity C. stiffness B. stress D. strain ANSWER: stiffness 23. Who coined the term “energy” in 1807? A. Thomas Young C. Lord Kelvin B. William Thompson D. William Rankine ANSWER: Thomas Young

24. A process during which the entropy remains constant: A. isentropic process C. polytropic process B. entropic process D. endothermic process ANSWER: isentropic process 25. A pure substance at absolute zero temperature is in perfect order, and its entropy is zero. This is known as: A. the zeroth law of thermodynamics C. the third law of thermodynamics B. first law of thermodynamics D. second law of thermodynamics ANSWER: third law of thermodynamics 26. A steel rod is stretched between two rigid walls and carries a tensile load of 5000 N at 20ºC. If the allowable stress is not to exceed 130 MPa at -20ºC, what is the minimum diameter of the rod? Assume α = 11.7 µm/m-ºC and E = 200GPa. A. 12.33 mm C. 13.22 mm B. 14.55 mm D. 16.22 mm SOLUTION:

y  yT  yL SL PL  αL ΔT  E AE 130 5000  11.7  106 40  3 200  10 A 200  103



A  137.4 mm







2

πd 2  137.4 mm 2 4 d  13.22 mm

ANSWER: 13.22 mm

27. A solid shaft 5 m long and 104 mm in diameter is stressed to 60 MPa when twisted through 4º. Using G = 83 GPa, what power can be transmitted by the shaft at 20 rev/s? A. 1.665 MW C. 6.155 MW B. 3.665 MW D. 7.244 MW ANSWER: 1.665 MW SOLUTION:

Ss  60 

16T πd 3 16T1000

π104 T  13,252 N - m 2

ρ  T 2ππ  power transmitted by a shaft ρ  13,252 2π 20 ρ  1.665 MW 28. What do you call the type of reaction in which heat is absorbed? A. endothermic C. exothermic B. redox rection D. isothermic ANSWER: endothermic 29. The ratio between the energy dissipated in some process and the heat appears as a result is the A. specific heat C. kilocalorie B. triple point D. mechanical equivalent of heat ANSWER: mechanical equivalent of heat 30. The light cable supports a mass of 12 kg per meter of horizontal length and is suspended between the two points on the same level 300 m apart. If the sag is 60 m, find the length of the cable. A. 329 m C. 139 m B. 239 m D. 429 m

ANSWER: 329 m SOLUTION:

ANSWER: Toricelli’s theorem

8d 2 32d 4  3L 5L3 2 4 860 3260 S  300   3300 5300 3 SL

S  329 m 31. The Golden Gate Bridge in San Francisco has a main span of 1280 m, a sag of 143 m, and a total static loading of 310.8 kN per linear meter of horizontal measurement. The weight of both of the main cable is included in this load and is assumed to be uniformly distributed along the horizontal. Calculate the midspan tension in each of the main cables. A. 233 MN C. 223 MN B. 322 MN D. 232 MN ANSWER: 23 MN SOLUTION:

ωL2  for two cables 8d 2 310.8  103 1280 2H  8142 2H  445 MN 2H 





H  223 MN 32. Two wires, A and B, are made of the same material and are subjected to the same loads. The strain is greater for A when A. has twice the diameter of B B. A has twice as long as B C. A has twice the length and half the diameter D. A has twice the diameter and half the length ANSWER: A has twice the length and half the diameter 33. Electron are emitted from a metal surface when light falling on it has a minimum A. energy C. wavelength B. velocity D. change ANSWER: energy 34. Who designed the atomic reactor? A. Wilson C. Rutherford B. Fermi D. Teller ANSWER: Fermi 35. Whenever a system is made to complete a cyclic process, the workdone during the complete cycle A. is zero C. is negative B. positive D. depends upon the path followed ANSWER: depends upon the path followed 36. Streamlined objects move more easily through fluids than those of irregular shape. The reason is that A. turbulence is decreased C. turbulence is increased B. viscosity is increased D. viscosity is increased ANSWER: turbulence is decreased 37. Two pieces of wire of the same material have their length in the ratio of 1:2 and diameters in the ratio of 2:1. If they are stretched by the equal force, elongation will be in the ratio of A. 1:2 C. 1:8 B. 2:1 D. 8:1 ANSWER: 1:8

40. In a city water system the water will flow A. from the mains to the water outlet B. only if the outlet is higher than the water in the water tower C. faster from a first floor tap than from one on the third floor D. only when the water tower has been completely emptied ANSWER: faster from a first floor tap than from one on the third floor 41. The nib of a pen is split keeping in view the phenomenon of A. diffusion C. osmosis B. capillarity D. cohesion ANSWER: capillarity 42. A double convex air bubble in water acts as A. converging lens C. diverging lens B. pane slab D. none of these ANSWER: diverging lens 43. What determines longitudinal chromatic aberration of a lens? A. Dispersive power only C. Focal length only B. Both dispersive power and focal length D. None of these ANSWER: Both dispersive power and focal length 44. The energies of photo electrons in photoelectric effect A. changes with intensity of light B. changes with frequency of light C. changes with velocity of light falling as the metal surface D. None of the above is correct ANSWER: changes with frequency of light 45. Which of the following functions is performed by a photocell? A. It converts chemical energy into electrical energy B. It converts magnetic energy into electrical energy C. It converts light energy into electrical energy D. It converts electrical energy into light energy ANSWER: It converts light energy into electrical energy 46. The maximum energy of emitted photoelectron is measured by A. the largest potential difference they can traverse B. the current they produce C. the potential difference they produce D. the speed with which they emerge ANSWER: the speed with which they emerge 47. The theory that light is emitted in discrete amounts of energy rather than in a continuous fashion is known as A. the photoelectric effect B. the quantum theory C. Huygen’s principle D. the electromagnetic theory ANSWER: the quantum theory 48. Which of the following colour phenomenon is not an interference phenomenon? A. Oil spread on the surface of water exposed to extended sources of light exhibits brilliant colours B. Soap bubbles in sunlight show colours C. Sky appears blue at noon but red in the evening and dawn D. Metallic surface when heated show colours ANSWER: Sky appears blue at noon but red in the evening and dawn 49. Air bubbles in water shines because of A. reflection C. refraction B. diffraction D. total internal reflection ANSWER: total internal reflection 50. When a helium atom loses an electron it becomes A. an alpha particle C. a proton B. a positive helium ion D. a negative helium ion ANSWER: a positive helium ion

38. The volume strain for a constant applied force increases directly with an increase in A. volume C. surface area B. compressibility D. bulk modulus ANSWER: compressibility

51. Emission of a β-particle from a nucleus A. changes its atomic number C. changes its mass number B. changes both the above D. None of these ANSWER: changes its mass number

39. Bernoulli’s equation includes as a special case A. Hooke’s Law C. Newton’s third law of motion B. Toricelli’s theorem D. Archimedes’ principle

52. Which of the following propagate at the same speed as velocity of light? A. Heat waves C. Sound waves B. Shock Waves D. β-rays ANSWER: Heat waves

53. The standard fixed point for calibrating a thermometer is A. the boiling point of water C. the boiling point of ice B. the temperature of steam D. the triple point of water ANSWER: the triple point of water 54. The gas thermometer is taken as the primary standard because A. the thermometers are easily reproducible B. readings can be accurately taken C. no corrections are necessary D. it reproduces the thermodynamic scale ANSWER: it reproduces the thermodynamic scale

55. The Carnot Cycle is a A. reversible cyclic process with two isotherms and two adiabatics B. constant pressure cycle C. constant-volume cycle D. a reversible two-stroke cycle ANSWER: reversible cyclic process with two isotherms and two adiabatics 56. The process by which nuclei emit α,β and γ- rays in order to attain stability is called A. radioactive disintegration C. β –decay B. radioactivity D. radioactive transmutation ANSWER: radioactivity 57. The process by which a heavy nucleus splits up into two lighter nuclei is known as A. fission C. fusion B. α – decay D. a chain reaction ANSWER: fission 58. Which atomic particle is used to cause fission in an atomic reactor? A. Alpha particle C. Beta particle C. Deuteron D. Neutron ANSWER: Neutron 59. The driver of an automobile traveling at speed ‘v’ suddenly sees a brick wall at a distance ‘d’ directly in front of him. To avoid crashing A. it is better to turn the car sharply away from the wall B. it is better to slam on the brakes C. the choice depends on the height of the brick wall D. it is difficult to decide ANSWER: it is difficult to decide 60. A particle having rest mass equal to that of electron but charge equal and opposite to that of electron is called A. proton C. positron B. hyperon D. meson ANSWER: positron 61. Which is the most massive particle? A. Deutron B. Neutron ANSWER: α – particle

C. α – particle D. Positron

62. Kelvin’s statement of the second law of thermodynamics is called the law of Degeneration because A. all the heat supplied to the working substance is converted into work B. in heat engines, heat can be converted to mechanical energy C. some of the heat supplied to the working of substance is not available D. the heat engine is not very efficient ANSWER: some of the heat supplied to the working of substance is not available 63: Thermodynamics is a subject dealing with A. the motion of molecules in matter B. The macroscopic variables, such as pressure, temperature and volume C. the motion of atoms in matter D. the kinetic energy of molecules ANSWER: The macroscopic variables, such as pressure, temperature and volume 64. Which of the following constitute β – particles? A. Electrons C. Protons B. Photons D. None of these ANSWER: Electrons 65. Why does nuclear fission requires high temperature? A. Because all nuclear reactions absorbs heat

rapidly

B. The mass deficit must be supplied C. The particles can not come together unless they move

D. The binding energy must be supplied from external sources ANSWER: Because all nuclear reactions absorbs heat 66. Who discovered radioactivity? A. M. Curie B. Both the above ANSWER: Bequerel

C. Bequerel D. None of these

67. The source of energy of the sun A. fusion of heavy nuclei C. fission of light nuclei ANSWER: fusion of light nuclei

C. fusion of light nuclei D. All of the above

68. Which of the following phenomenon is responsible for the production of shadow? A. Interference C. Diffraction B. Polarization D. Rectilinear propagation of light ANSWER: Rectilinear propagation of light 69. The defect in image due to oblique centric rays falling on the lens is called A. astigmatism C. coma B. curvature of image field D. spherical aberration ANSWER: curvature of image field 70. The burring of the image due to dispersion in lens is called A. spherical aberration C. chromatic aberration B. astigmatism D. curvature of image field ANSWER: Chromatic aberration 71. When a body is accelerated A. its velocity always changes C. its direction always changes B. its speed always changes D. its falls towards the earth ANSWER: its velocity always changes 72. A 2000 kg truck traveling at 36km/hr strikes a tree and comes toa top in 0.1 sec. The average force on the truck during the crash is A. 2x103 newtons C. 2x102 newtons B. 2x104 newtons D. 2x105 newtons ANSWER: 2x105 newtons 73. When a charged particle moves through a magnetic field, it suffers a change in its A. charge C. energy B. mass D. direction of motion ANSWER: direction of motion 74. Lenz’s law follows from the law of conversion of A. mass C. charge B. energy D. momentum ANSWER: mass 75. If a car is moving towards you with its horn sounding, you hear a higher pitch than you would hear if the car were at rest, this is because A. the waves travel faster B. successive crests produced by the horn are closer to each other C. you received successive crests more frequently even though the wave itself is unchanged D. the motion of the car raises the frequency of the horn ANSWER: you received successive crests more frequently even though the wave itself is unchanged 76. A tuning fork A produces 4 beats with a tuning fork B of frequency 256. A is filled at the top of the prong and the number of beats increases. What was its original frequency? A. 260 C. 258 B. 252 D. 250 ANSWER: 260 77. Neutral temperature of a thermocouple is the temperature at which A. the thermo e.m.f. changes sign B. the thermo e.m.f. is maximum C. the thermo e.m.f. is minimum D. the thermo current is maximum ANSWER: the thermo e.m.f. is maximum 78. Factor of safety may be defined by

A. yielding stress/yielding stress stress/yielding stress B. breaking stress/working stress ANSWER: breaking stress/working stress

C. working D. all of the above

79. The first patented diode used as a detector for ratio signal is credited to A. Edison C. de Forest B. Fleming D. Thomson* AMSWER: Thomson 80. A fathometer is an instrument used to measure A. velocity of sound C. frequency of sound B. depth of sea D. wavelength of sound ANSWER: depth of sea 81. A satellite travels in a circular orbit at a speed of 20,000 km/h to stay at a constant attitude. To escape from the earth, the speed would have to be increased to A. 28,000 km/h C. 21,000 km/h B. 40,000 km/h D. 64,000 km/h ANSWER: 40,000 km/h

82. When a car is traveling at constant speed around a circular track, a quantity that is constant but not zero is A. acceleration C. angular velocity B. velocity D. angular acceleration ANSWER: angular velocity 84. Which element has the highest ionization energy? A. Na C. Li B. K D. Cs ANSWER: Li 85. Kinetic energy of molecules is highest in A. solids C. gases B. liquids D. solutions ANSWER: gases