Bouncy Ball Experiment
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Bouncy Ball Experiment
The aim of this experiment is to investigate the efficiency of a bouncing ball, and the factors which affect its efficiency.
Prediction
I predict that the higher I drop the ball from the higher it will rebound up, because it will have more gravitational potential energy the higher dropped from. As it is dropped the ball will have kinetic energy, and then when it hits the ground changes to heat and sound energy, and kinetic as it rebounds back up. The higher up the ball is dropped from the more gravitational potential, more kinetic energy on the way down and therefore more sound heat and kinetic energy when hitting the ground. The ball will bounce higher the higher dropped from as the energy has to go somewhere! The balls efficiency (what fraction of the energy the ball has left after being dropped), will when dropped from a small height i.e. 25cm, be a high percentage, because air resistance wont affect the ball. As the height dropped from increases the ball will bounce higher but the amount it increases by will get less. (See graph) This is because as the ball is dropped from a higher height the amount of kinetic energy on the way down is greater, this could make the ball reach terminal velocity, but even if it does not air resistance will affect it more. The ball will reach a certain height where it reaches terminal velocity on the way down and will rebound up as high as it if it was dropped from a higher height.
Theory:
The ball has gravitational potential energy at point A just before it is released.
As the ball falls from point A to B it has kinetic energy.
At B just before the ball hits the surface it has gravitational potential and kinetic energy.
When the ball hits the surface and deforms it has elastic energy.
At point C when the ball is rebounding and travelling upwards it has kinetic energy.
At point D when the ball has reached its maximum rebound and is momentarily stationary it has gravitational potential energy.
The height of the ball at point D (its maximum rebound height) is lower than the point A (the height the ball was dropped from) it shows that the ball has lost energy.
This shows that when the ball hit the surface it lost energy through sound and hitting the air, sound and heat energy was involved.
The equation for gravitational potential energy is:
Mass x gravity x height
The equation for efficiency of an energy transfer process is:
Useful energy input
Useful energy output x 100
The efficiency in the ball situation is:
Mass at start
Mass at end x 100
The total of the energy input is at point A on the diagram at the start.
The useful energy output is at point D at the end.
To calculate the efficiency of the bouncy ball the equation to use is:
Height at end
Height at start x 100
Before doing my experiment I conducted a preliminary experiment using different types of balls. A variable which I wont change when conducting my experiment, firstly at 1m with all the balls and then at 0.5m with all the balls. I dropped each ball 3 times to get an average and a more accurate result.
1st Drop at 1m (cm)
2nd Drop at 1m (cm)
3rd Drop at 1m (cm)
Average (cm)
Efficiency (%)
Ping Pong
63.33333333
63.33333333
Tennis
56.66666667
56.66666667
Bouncy
Squash
68.33333333
68.33333333
Ist drop at 0.5m (cm)
2nd Drop at 0.5m (cm)
3rd Drop at 0.5m (cm)
Average (cm)
Efficiency (%)
Ping Pong
35.33333333
70.66666667
Tennis
Bouncy
39.66666667
79.33333333
Squash
Diagram