# GPE and half of its KE - Sample Essay

This is why I am going to leave the ball in the water bath for 3 minutes for it to reach thermal equilibrium. I Am going To investigate a appropriate height to let go of the squash ball , I will let go of the squash ball at 20i?? C, 40i?? C and 70i?? C from different heights to find a height that worked well for all the temperatures. The heights I let go of the ball from were: 0. 50m, 0. 75m, 1. 00m, 1. 25m and 1. 50m. To ensure the temperatures of the ball were correct I kept the ball in the water bath for 3 minutes as I understand from my earlier original results that 3 minutes is the time it takes the ball to reach thermal equilibrium.

You can understand from this that 1 meter is a appropriate height that I can easily record all the heights down to the lowest temperature (0i?? C) and gives a first-class bounce height for 70i?? C so it satisfies both ends of the series of temperatures. This height gives a good choice of results so they can be shown easily in a graph and compared. I chose not to use the higher heights since even though they would also give a precise range of results and I would easily be able to understand the height of the ball at a 0i??

C temperature, it was unsuitable for my experiment since it meant that I would keep getting up onto the table to be able to reach the heights. This would cause a safety hazard and would not be suitable for the experiment when a meter will give just as even results and result range. Consequently from my initial work I will be using a drop height of 1 meter and leave the squash ball in the water bath for 3 minutes for it to reach thermal equilibrium. My results are shown in the table below: Test Results THIS TABLE SHOWS THE EFFECT OF HEAT ON A SQUASH BALL Temperature (i?? C) Test 1st (m) 2nd (m).

From the results I have got I have been able to use the averages to plot points on a graph with a line of best fit so the information is obviously displayed and I can analyse the shape of the graph to see what it shows me. From these results and the graph I have got I can understand that the 10i?? C average result was an anomaly so I chose to do it a second time to check the results.

The second time these are the results I got: Temperature (i?? C) Test 1st (m) 2nd (m) 3rd (m) 4th (m) 5th (m) Average (m) This is the results which are much better and fitted in better with the line of best fit. So I have chose to use my new results for 10i?? C and discount my old results as they are not accurate and would not be of any use to the rest of the investigation. Analysis: From these results I can understand that my prediction is right because when the temperature increases the height of the bounce also increases.

I can understand this because as I know that when the gas inside the ball heats up, the volume of the gas expands and the molecules move more quickly and will often make them hit the sides harder and more often . This allows the rubber to get larger and then store more elastic energy. You can see from this that the bounce height is bigger as the more stretched the rubber is, the better it converts elastic potential energy into kinetic energy when the ball hits the floor and allows the ball to bounce higher.

Also, the hotter the ball is, the stronger it is and the faster it will get its shape back, thus it loses little energy and then has additional energy to use to bounce higher. This proves that I am right because before the ball is dropped, energy is contained as GPE (gravitational potential energy). Since the ball is let go off its speed increases and the GPE is changed into KE (kinetic energy), so half way through the drop half of the ball’s energy is GPE and half of its KE.

Instant before the ball touches the floor all its energy is KE (kinetic energy) and it’s not GPE (gravitational potential energy). As soon as the ball hits the floor, all the KE (kinetic energy) is changed into EPE (elastic potential energy) and some of it is lost because the heat and sound energy which makes its energy less than its original GPE (gravitational potential energy). as soon as the ball hits back off the floor the EPE (elastic potential energy) is turned back into KE (kinetic energy), heat and sound.