# Defying Gravity

Topics: Gravitation, Mass, Balls Pages: 10 (1542 words) Published: May 14, 2014
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Contents

Defying Gravity
M.C. Herden

Abstract: This report will investigate two theories about gravity, these including Aristotle’s theory, of which states, the heavier the object, the faster it falls, alongside Galileo’s trialed theory; Two object of different masses, when dropped from the same height will reach the ground at the same time. Correspondingly, this investigation shall trail and prove correct Galileo’s theory of gravity. Introduction and Background: Gravity is the attraction of all masses in the universe, similarly, it is not possible to have gravity without mass. Although Aristotle, a Greek philosopher, was the first to try and explain gravity, Galileo was the first to correctly understand it. Aristotle believed that the heaver the object the faster it falls. This is understandable if a feather and a stone were dropped from the same height. However Aristotle failed to further test his hypothesis in order to take into consideration other variables such as air resistance, surface area and friction. Galileo conducted many experiments to prove his theory correct that objects of different masses, dropped from the same height will reach the ground at the same time. (Kallos, 2004) Galileo also deduced that in a vacuum, all objects fall at the same rate as there was no other forces acting on the bodies. (Giancoli, 1980) Using Newton’s second law, F = ma, it is clear that Galileo’s theory of objects falling at the same rate is correct. As F = W = m g, (where W is the weight of the object and mg is the weight) the acceleration of the free falling objects is not affected by its mass. This is shown in Figure 1 below.

Figure 1

Experimental Procedure

Aim/ hypothesis: The aim of this experiment is to determine Galileo’s theory of gravity that objects of different masses that are dropped from the same height will reach the ground at the same time. It is predicted that Galileo’s theory will be proved correct and that the masses tested will reach the ground at the same time. Materials:

2 x Metre Rules
2 x 4.5cm thick textbooks
1 x Stopwatch
4 x Balls of different masses. (Tennis, Golf, Ping Pong and Rubber Ball) Method:
1. Set up the experiment using one 4.5cm thick textbook as the height to lay 2 x one metre rules on diagonally, with the ends on the edge of the textbook to create a ramp, as shown below:

2. Release the first ball from the top of the rules whilst timing how long the balls takes to reach the base of the rules using the stopwatch. 3. Repeat three times for each ball, record findings.

4. Repeat the steps 1 – 3 only changing the height to 9cm (two textbooks) or changing the length of the rules to either 25cm, 50cm or 75cm. 5. Graph and analyse results.
Results:
When Height = 4.5cm, Hypotenuse = 100cm (1m)

Ball
Mass (g)
Trial One
Trial Two
Trial Three
(s)
Golf Ball
39.4
2.79
2.75
2.84
2.79
0.36
Ping Pong Ball
2.1
3.34
2.62
2.85
2.93
0.34
Tennis Ball
56.6
3.44
3.287
4.00
3.57
0.28
Rubber Ball
51.2
2.97
3.12
3.46
3.18
0.31

When Height = 9cm, Hypotenuse = 100cm (1m)

Ball
Mass (g)
Trial One
Trial Two
Trial Three
(s)
Golf Ball
39.4
2.10
2.06
2.19
2.12
0.47
Ping Pong Ball
2.1
2.09
1.93
1.94
1.99
0.50
Tennis Ball
56.6
2.16
2.09
2.16
2.14
0.47
Rubber Ball
51.2
2.00
2.00
2.29
2.10
0.48

When Height = 4.5cm, Hypotenuse = 75cm

Ball
Mass (g)
Trial One
Trial Two
Trial Three
(s)
Golf Ball
39.4
2.19
2.22
2.06
2.16
0.35
Ping Pong Ball
2.1
2.15
2.28
2.10
2.18
0.34

When Height = 4.5cm, Hypotenuse = 50cm

Ball
Mass (g)
Trial One
Trial Two
Trial Three
(s)
Golf Ball
39.4
1.38
1.38
1.28
1.35
0.19
Ping Pong Ball
2.1
1.57
1.53
1.41
1.50
0.17

When Height = 4.5cm, Hypotenuse = 25cm

Ball
Mass (g)
Trial One
Trial Two
Trial Three
(s)...

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Geddes, S.M. 1981, Advanced Physics: Gravitation - The Acceleration due to Gravity, Macmillian Education Limited, Hampshire, pp. 116-118.
Giancoli, Douglas C. 1980, Physics - Principles with Applications: Circular and Rotational Motion; Gravitation, Prentice-Hall, Inc., New Jersey, pp. 70-73.
Kallos 2004, 'A Brief History of Gravity ', University of Southern California, [Online], Available: http://www-scf.usc.edu/~kallos/gravity.htm [2012, May 5].
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