Pencil Stopwatch

Title: Acceleration due to gravity Aim: Plan and design an experiment to find the value of acceleration due to gravity Apparatus/Materials:  Pencil  Stopwatch Diagram:

Principle/Theory: 1 When something falls freely the displacement 𝑠 = 𝑢𝑡 2 𝑔𝑡 2 . Where the initial velocity is u = 0 1

ms-1.Therefore 𝑠 = 2 𝑔𝑡 2 hence𝑔 =

2𝑠 𝑡2

.

Procedure: 1. The height a section of a wall was measured with a ruler 2. The height of the wall was divided into 5 parts 3. A pencil was dropped at each height and timed 4. The time taken for the pencil to fall was recorded along with its corresponding height 5. The results were tabulated

Observations/Results: Displacement(cm) Time (s) 0.88 0.43 0.80 0.40 0.72 0.3.8 0.64 0.36 0.56 0.34 TABLE SHOWING THE DISPLACEMENT OF THE PENCIL AND THE TIME IT TOOK TO FELL.

Calculations: 𝑔=

2𝑠 𝑡2 2(0.88)

1.76

2(0.80)

1.6

g = (0.43)2 =0.1849=9.52 ms-2

g=

(0.4)2

=0.16 = 10 ms-2

2(0.72)

1.44

2(0.64)

1.28

2(0.56)

1.12

g = (0.38)2 =0.1444 = 9.97 ms-2

𝑔 = (0.36)2 =0.1296 = 9.87 ms-2

g = (0.34)2 =0.1156 = 9.68 ms-2 Average g

9.52 + 10+ 9.97 +9.87+9.68 5

= 9.8 ms-2

Discussion: A force is a push or pull, which one object applies to another object .Forces always involve an interaction between two objects. When objects are joined together or in contact, the forces are known as contact forces. When the force acts over a distance without any direct contact, the forces are called non-contact forces. The regions over which non-contact forces act are called fields. The gravitational attraction between the earth and the moon is a non-contact force. The Earth’s gravitational field is the region around the earth where there is a force on masses due to the Earth’s gravity. In this region, an object not acted on by the other forces will accelerate towards the earth. This acceleration due to the Earth’s gravitational force is called ‘g’. It is also called the Earth’s gravitational field strength. The units of g are usually given as either ms-2 or Nkg-1.

Conclusion It can be concluded that the acceleration due to gravity is 9.8 ms-2 Limitations:

❋ Sources of error  It was ensured that the readings taken properly.  It was ensured that the experiment was done more than once to obtain readings that are more accurate. ❋Precaution  

The stopwatch might not have been stopped on time. The height of the wall might not have been measured correctly.

Reflection: The Earth’s gravitational field even affects astronauts in orbits around the earth. They experience ‘weightlessness’ even though they are not‘weightless’. Because they are in orbit and so freely towards earth, (their sideways movement as well means they never actually get any closer to Earth) they don’t feel any resultant force from their surroundings, so they feel as though they have no weight.