The diagrams above show the conversion between potential and kinetic energy. At point A the ball is dropped. The force of gravity is a pull making it gravitational potential energy. Gravitational potential energy is calculated by mass x gravity (about 10m/s/s on earth) x height. Point B is where the ball is falling; this is where it has been converted to kinetic energy because the ball is in motion.
At point c the ball looses the most energy because it is compressed making the particles distorted more, which takes more energy to do. Then at point D the ball bounces back up and is in kinetic energy again. Then at point E the energy returns to gravitational potential energy, as it is about to fall down again. Through this the ball is loosing energy through air resistance and heat as well as bouncing so on each bounce the height would be lower due to less energy.
Method
The equipment I will need:
- Ruler
- Squash ball (same one each time)
- Clamp and stand
- A surface (to be kept the same each time)
This is how the experiment will be set up:
To do this experiment I will first choose suitable heights to drop the ball form as if I drop the ball from a too large height then it will bounce too height and I will not be able to record the results I gained because the ruler will not reach high enough or it will be inconvenient to find a place big enough to reach very height heights. For this I found that heights between 1 and 2 meters are suitable. Then I will drop the squash ball from my chosen height and measure the height of the bounce. I will do this by measuring it once and guessing where the ball bounces up to then I will repeat this but because I will know the sort of height the ball is going to bounce at I can get a better reading. I will then repeat this to get an even more accurate reading. This will be one result. I will then repeat this 3 times for each height and take the average. After I have done this for one height I will try it for others.
Precautions I will take to make sure my results are accurate:
- The surface is the same to make a fair test
- Only the same ball is used
- The experiment is repeated 3 times and an average taken to make sure no results are odd
- Odd results are taken out and repeated
- The temperature of the ball is the same
- No other variables are changed
If I were doing the temperature experiment I would need to take safety precautions to make sure that the hot water used to heat up the ball did not burn anybody. I could do this by wearing safety goggles and keeping people out the way of the water. However for this experiment I feel that there are no real dangers.
Results
This is a the table of results to show what our experiment showed:
When I did the experiment we thought that the experiment for test 2, 1.5 m was an odd result so I repeated the test again and gained these results, which look more correct:
Graph
I have included my graph at the back of this investigation.
Conclusion
The shape of my graph shows a curve that shows height of bounce increases proportionally when the height drop is increased.
I think this has happened because as the ball drops it gains energy and from a higher height it has more time to gain energy so it picks up more speed and this results in the ball having more energy when it hits the surface so there is more energy left to be released in the bounce. This makes the bounce higher because there is more energy to do so.
This agrees well with my original prediction because this is what I though would happen however my results do not show it exactly.
Evaluation
I think my results are fairly accurate because most agree with my conclusion however I feel that they could have been recorded slightly more precisely only if I had the time. They are reliable enough to show the general response of balls dropped from different heights but I don’t think they are reliable enough to pinpoint exactly what height a ball would bounce to from a certain height.
I had one odd result in my table before I re did the experiment, I think this we because I pushed the ball down with a force instead of just letting it drop. Therefore I gave the ball extra energy for the bounce. I had a couple of problems with the method because I found it hard to correctly pinpoint the height of the bounce just by seeing where I thought it went up to on the ruler and that the ruler kept slanting to one side in the clamp stand. We made improvements to keep the ruler steadier by taping it to the clamp stand. I could have used a video camera and recorded the bounce of the ball and replayed it in slow motion to overcome the other problem but I did not have these facilities. To extend this investigation I could investigate other aspects of the height of bounce such as the temperature of the ball or I could improve on this investigation by doing more heights to see if there is more proof to go with my conclusion.