Step 2: Set up the clamp stand and clamp on top of a desk. Using the clamp, attach a 1m long ruler vertically to the stand and make sure one end is touching the desk.
Step 3: After 5 minutes, remove the squash ball from the beaker (remembering that the water maybe hot, I used a pair of tongs to remove the ball as a safety precaution). Stand on the desk and hold the ball 30cm from the desktop. Ask a partner to stand next to the desk and watch the ball drop and to record the number of centimetres that the ball bounces back up after hitting the desk. Drop the ball three times from each height.
Step 4: Place the ball back in the beaker (check that it is still at 45°c, alter with hot or cold water as required) and record the results in a table.
Step 5: Repeat stages 1 - 4 fourteen times but change the drop height and make sure that the water and ball are both kept at 45°c. The drop heights should be changed to the following heights:
35cm 40cm 45cm 50cm 55cm 60cm 65cm 70cm 75cm 80cm 85cm 90cm 95cm and 100cm.
The ball must be kept at 45°c to make the test fair.
I recorded all 15 results in a table, worked out the average of the three measurements for each height and worked out the average bounce height for each drop height. I drew up a graph to try and find a pattern with my results as shown below.
To keep the test fair, I kept the ball at a constant temperature of 45°c in a beaker of water of the same temperature. I repeated the drops of different heights three times to ensure that I obtained a good set of averages to draw up my graph from.
The experiment was set up on a desk to allow a second person to sit on chair at eye level with the bottom half of the ruler in order to get as accurate a result as possible (although I may stress that, because it was only human vision and no high-tech measuring equipment, the results will never be 100% accurate and are only a good estimate based on judgement).
Results:
⇑ These results are based entirely on visual judgement of the naked eye and are not 100% accurate.
Conclusion: The graph shows that the bounce height increases as the ball is dropped from a greater altitude. This proves that the potential energy increases as it gets higher from the ground and therefore produces more kinetic energy as it falls. The range of bounce heights in the table range from 9.4cm to 33.6 with a gradual range of difference building in between. The averages helped to establish a good graph with which I could draw my conclusion and I think the results came out accurate enough to state that my prediction was correct.
Evaluation: With the results table and graph appearing in basically the same pattern that I predicted, I can now say that the higher that an object is dropped from, the more potential energy it will contain and when dropped, it will convert into kinetic energy. The fact that I did not use visual aids made it difficult to make the results very accurate but I managed to judge the heights well enough to make a pattern from my results table.
To improve my experiment, I could have used a motion sensor to accurately record the height of the drop and also the height of the bounce. I could also have used something with which I could drop the ball from a fixed height instead of my hand which wouldn’t have been able to remain still at a certain height without moving even a little bit.
My results were fairly accurate but as I have already stated, they cannot be 100% accurate by using only my own eyes. None of my results appear to have been odd except for a few of the averages which were higher than the succeeding average (eg. when the average goes from 26.5 to 24.4 then to 29.8). This may have been due to the temperature of the ball dropping.
To extend my research into this investigation, I could use larger objects such as a tennis ball dropped from a desk, a football dropped from a window or even a wrecking ball dropped from a building (although the latter would be a bit strenuous to repeat so many times). I could also try dropping balls from different temperatures, such as colder or warmer to see if the bounce will increase at different temperatures.
