I am going to drop the squash ball onto the same lab surface throughout.
These variables will be kept constant in order to ensure that the experiment is a fair test.
Safety
I will be wearing goggles and working around a clear area of drop zone to ensure that I do not injure myself or any other pupil working on the same experiment. The main hazards will be the hot water and the squash ball.
Apparatus
1 squash ball, 1 metre rule (graduated in mm), a Bunsen burner, a beaker, a thermometer (graduated in degrees) and goggles.
Procedure
To the heat the ball, I will be placing it into a water filled beaker at different temperatures varying from room temperature to the boiling point of water, i.e. 24°c to 100°c. This will be in 10°c intervals and I will record each in a results table. I will record how high the squash ball bounces each time. I will be leaving the ball in the beaker for one minute each time so it gains the water’s temperature because rubber is a very poor conductor of heat. I will then drop the ball within 5 seconds of taking it out of the beaker. Three readings of each temperature will be recorded.
Prediction
I predict that as the temperature increases, the height of the bounce will also increase. This is because there are air molecules inside the squash ball. When you supply heat energy to the air molecules inside the squash ball, it increases the rate at which the molecules move, which creates kinetic energy. Therefore the molecules will begin to hit the inner walls of the ball with a greater force, which in turn makes the internal pressure increase the bounce. As the air molecules inside the ball move, they create more kinetic energy. Therefore, the higher the pressure, the higher the bounce of the ball.
The squash ball was dropped from a constant height of 500mm/50cm throughout the preliminary experiment. I will be using the same height for my main experiment.
Method
I carried my main experiment out just as I did to obtain my preliminary results. I heated the squash ball up to different temperatures using a Bunsen burner, and then measured the bounce height of the ball with a ruler. The bounce heights were recorded three times for each temperature in order to sustain a fair test and identify any anomalies.
After conducting my main experiment I collected my data which was very similar to my preliminary results. They both proved that my prediction was right. My preliminary results did influence the way in which the experiment was conducted as I used the same release point and used the same range of temperatures. Therefore my conclusion to this experiment is that, as the temperature increases, so does the height of which the squash ball bounces.
Evaluation
Overall my experiment went very well. I was able to collect my results with few difficulties and that therefore enabled me to analyse my data precisely. The experiment proved my earlier prediction correct, by showing that as the temperature of the squash ball increased, the ball bounced higher when released from a resting position. I only made a few changes throughout the experiment but such things as the height at which the ball was released was kept the same.
The difficult part of attaining my results was being able to read off the bounce height of the ball.
There are many ways in which my experiment could have been improved. For example, such things as keeping the squash ball and its dropping zone at a constant temperature, which would have prevented any cooling down or energy loss. Even though the water was at a known temperature, when removed, the ball cooled and so the temperature recorded from the water, was not the actual temperature of the ball when dropped. The perfect equipment for this experiment would have been a video recorder with a slow motion option. This would have given us the chance of replaying the incident and noting down the correct bounce height.
The figures recorded for each temperature were quite reliable seeing as though they are all within 2˚c of each other. However, this still might be too wide of a gap and therefore would mean the results are not reliable enough. To make sure of the reliability of my results, I would have to record more results and identify the anomalous data. For example, for my results at 80˚c, there is a range of 3˚c between my 2nd and 3rd attempt. However, in my first set of results at 20˚c, there is only a gap of 1˚c between each of the three. This means that my results at 80˚c are less reliable than my others.