Bouncy Ball Experiment

Bouncy Ball Experiment

Aim:

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 ball’s 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 won’t 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 won’t 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.

Ball 1st Drop at 1m (cm) 2nd Drop at 1m (cm) 3rd Drop at 1m (cm) Average (cm) Efficiency (%)

Ping Pong 61 66 63 63.33333333 63.33333333

Tennis 55 57 58 56.66666667 56.66666667

Bouncy 75 71 73 73 73

Squash 36 34 35 35 35

Golf 64 70 71 68.33333333 68.33333333

Ball Ist drop at 0.5m (cm) 2nd Drop at 0.5m (cm) 3rd Drop at 0.5m (cm) Average (cm) Efficiency (%)

Ping Pong 37 38 31 35.33333333 70.66666667