Table Tennis Ball.

Physics Coursework 2004

Table Tennis Ball Experiment

Prediction

The table tennis ball will bounce lower as the height that it is dropped from decreases. This is because as the ball gets lower there is a lesser amount of force pushing the ball downwards therefore giving less velocity for it to rebound up into the air. This means that when it hits the ground the atoms push each other away forcing the ball to bounce higher.

The graph begins to level out because parts of the ball begin to melt at certain temperatures as the atoms get more energy and break their bonds turning the ball into a liquid. A theory, which links into this experiment, is the kinetic theory. This is because the kinetic theory deals with atoms vibrating as they receive more energy and in doing so breaking their bonds. This is linked to this experiment because as the squash ball's atoms get more energy and vibrate more before breaking their bonds to become a liquid.

Method

We set up the apparatus as shown in the above diagram. We then dropped it from 100 cm high and measured the bounce. We then repeated the experiment 9 times, each time dropping it 10cm lower. To keep the experiment fair the only variable, which we changed, was the height. We used the same ball through out the experiment and checked the ruler had not moved. My range of results was very wide in order to get an accurate set of results. Some of the results needed to be repeated to make sure that they were accurate.

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Method

Results

Analysis

From my results I can conclude that as the temperature of the ball raises the height of the bounce gets higher. This is in line with the kinetic theory, which defines that as the ball gets hotter the atoms get more energy and vibrate more. When the ball hits the surface then the atoms are pushed together and because they are vibrating more they push each other further away causing the ball to bounce higher. In this experiment the kinetic theory only lasts for a specific set of temperatures. This is because when the ball hits a certain temperature it starts to melt. At 0 degrees Celsius the ball will still bounce as the atoms are still vibrating. The graph proves that the theory works for this experiment, as it is a straight line to start with. However as the ball gets nearer the critical temperature the extra height it bounces becomes less and less. This is shown as the graph levels off. The sketch graph I drew in my prediction matched the real graph showing that the science I used to explain my prediction was correct.

Evaluation

Looking at my results I can say that they were quite reliable and accurate. I had one anomalous result even after an average over five measurements. I can say that looking at my results when I repeated results they were quite close together. I think that I did the experiment quite well although I found it hard to spot where the ball bounced too. This is why I did an average over 5 measurements. To improve the experiment I would need to use specialist equipment like lasers so I could be sure where the ball bounced too. Ways in which I could extend this experiment are to use a different kind of rubber in the ball so that it doesn't melt at such a low temperature this way I could carry on to see whether the kinetic theory is still right at higher temperatures. Also I would like to see what happened when the ball was at 0 degrees Celsius. I would like to do this to see whether the atoms still vibrated causing the ball to bounce. If it did I would like to carry on getting lower and lower to see whether there was a temperature where the atoms no longer vibrated (Absolute Zero)