This is because the gravitational potential energy of the tennis ball is changing to kinetic energy (KE) of the ball and KE the ball is changing to GPE.
I also predict that if the dropping height is double, I expect the rebound height to be double.
Equipment:
- Tennis ball
- Two meter rulers
- Clamp stand
Factors that will affect the bouncing height of the tennis ball:
If I drop, a tennis ball from a certain height the ball will rebound from the surface. The rebound height of the ball depends on the following factors:
1. The height from which it is dropped.
2. The surface at which it is failing.
3. Air resistance faced by the ball.
4. Temperature of the ball
I am going to investigate the height from which the tennis ball is dropped.
Diagram:
Plan:
If I drop a tennis ball from a height of one meter the gravitational potential energy is changed to kinetic energy of the tennis ball.
The ball is losing gravitational potential energy and gaining kinetic energy when the ball hits the surface some of its kinetic energy is lost through sound and heat. This is because of the initial velocity of the ball is less when the velocity at which the ball hits the ground and consequently the height gained after rebound will be less.
The loss of kinetic energy by hitting the surface is also dependable on the surface itself. On a hard surface, the tennis ball will lose less kinetic energy and such it would bounce a higher height.
A soft surface will absorb more kinetic energy and bouncing would be less.
Method:
1. Set up all equipment as shown in the diagram.
2. I am going to drop a ball and see when it rebounds how high it goes.
3. Measure the height this will be dropping height.
4. Allow the ball to drop and measure the rebound height.
5. Double check readings, by doing the experiment again.
6. When it rebounds, I am going to be at eye level with top of the ball so I can get an exact measurement.
7. Repeat experiment three times.
8. Record dropping height and rebound height on a results table.
9. Repeat 3 to 8 from different dropping heights.
10. Use six different dropping heights.
Fair test:
- To make this test fair I will make sure that I use the same part of the ball to measure the height from (the top).
- Make sure that it bounces on the same surface each time.
- Double check rulers are straight and touch the floor.
Result Table:
Average for Results:
Graph:
Analysing the Result and drawing Conclusions:
I have drawn a line graph of dropping height against bouncing height and the line of best fit is drawn. From the line graph, I have found that the bouncing height is proportional to the dropping height. When the dropping height is 0.5 meters the bouncing height is 0.26 meters. Again when the dropping height is 1.5 meters the bouncing height is 0.67 meters. The results proved my prediction. I have also found out that the bouncing height is wrong when the dropping height is 1.75 meters, the bouncing height is 0.8 meters but according to the line of best fit it should be 0.9 meters.
As I mentioned in my prediction that if the dropping height is higher, the bouncing height will be higher as well. From the measurement of dropping height and bouncing height, I am able to estimate the amount of energy lost when the tennis ball was hitting the floor.
From the information we collected, we can find the loss in gravitational potential energy when the tennis strikes the floor.
For dropping height of 1 meter
Gravitational Potential Energy = mgh
=m x 10 x 1 J (joules)
= 10m J
Energy gained by the tennis ball hitting the floor
= mgh
=m x 10 x 0.48
=4.8m J
Energy lost
=10m J - 4.8 m J
=5.2m J
Percentage (%) of Energy lost
= (5.2m J / 10m J) x 100 = 52%
For dropping height of 1.75 meters
Gravitational Potential Energy
=mgh
=m x 10 x 1.75 J
=17.5m J
Energy gained by the tennis ball after hitting the floor
=mgh
=m x 10 x 0.797 J
=7.97 J
Energy lost
= 17.5m J - 7.97m J
=9.53m J
Percentage (%) of Energy lost
= (9.53m J/17.5m J) x 100
=54%
This shows that the higher the dropping height, more energy is lost through sound and heat when the tennis ball strikes the floor. This energy loss can be reduced by using hard and smooth floors.
Evaluation:
I think that the procedure used was fairly suitable, although not as much as I would have liked it to be, because we just used a ruler to measure the bouncing height. It is very difficult to measure accurate bouncing height of the ball due to nto being excaltly eye level. Because of that, we might not actually have been measuring the bouncing height from the place we intended. However, this should not have affected my results too much.
The results I have recorded were accurate, although I had one odd result. This may be due to taking the wrong readings of the bouncing heights.
To make my experiment more accurate, I could have used a sensor to measure the bouncing height of the tennis ball and repeat the experiment three times and found an average. I don’t think I could really improve on the way (the plan or method) the experiment was performed because my results were quite accurate. I also found that the experiment was quite easy to set up as it was simple and not complicated.
Further experiments I could do to see the effect of bouncing height of a tennis ball would be to whether the following factors would make a difference in the bouncing height.
The surface on which the ball is dropped: I think the bouncing height would increase if the tennis ball is dropped on a hard surface.
