The Effect of Temperature on a Squash Ball Bounce.

The Effect of Temperature on a Squash Ball Bounce

Jenny Clout

In this experiment I will be heating or cooling a yellow dot squash ball to different temperatures to see if it has an effect on the height of its bounce. To make this experiment a fair test I will be using the same ball throughout, also I will be dropping the ball from the same height each time onto the same type of surface.

My prediction is that when the squash ball is heated to higher temperatures the bounce will increase, as the air particles in the ball will have more energy. When the air particles inside the ball have more energy they are moving faster and have more collisions with themselves and the inside surface of the ball. There then is more pressure inside the ball at higher temperatures as the squash balls' volume is fixed. If volume is constant the pressure divided by the temperature will be constant also (higher temperature = greater pressure at fixed volume).

Key Factors

The variables in this experiment could be the type of squash ball, so the pressure of the air in the ball. I could change the type of surface that the ball would be dropped onto, for example a carpeted surface would have a lower bounce than on a tiled surface. Other variables would be the height at which the ball was dropped, the material of the ball, the acceleration due to gravity, the balls’ mass, the angle of the surface to which the ball is dropped also the air resistance.

Apparatus

1 yellow dot squash ball

2 meter rules

1 beaker

A Bunsen burner

Heat proof mat

Tripod

Gauze

100°C Thermometer

Tongs

Timer

Paper towel

Heat proof gloves (optional)

Scientific Knowledge

When something is elevated off a surface, it is said to have gravitational potential energy and when it is released this G.P.E is transferred into kinetic energy. G.P.E and K.E are interchangeable.
½mv²= mgh.
An elastic solid returns to its original shape after experiencing a deforming force which is then removed. The squash ball is an elastic solid.
Squash balls are not very bouncy, they deform when they hit the floor, and a lot of energy is converted into heat energy during the collision so there is less energy to bounce back up.
When a fast moving particle of gas inside the squash ball collides with the outer surface both the particles and the outer surface experience a force. Pressure = Force / Area. (Physics 1)

When a squash ball is heated, the air particles in them gets more pressurised, when they get more pressurised the particles move faster and collide more. If I had 100J of G.P.E right before the collision there would be 100J of K.E (ignoring air resistance). When the ball hits the floor this K.E transforms into so many Joules of Deformation energy, Sound energy, Heat energy and the rest is Kinetic energy going upwards. If I had a higher pressure inside the ball there would be less deformation energy when the ball hits the ground and more kinetic energy upwards, more G.P.E upwards therefore a greater bounce height. Kinetic energy and Gravitational potential energy are interchangeable. This makes my prediction correct, if I heat the ball to greater temperatures the bounce of the ball will increase. (Understanding physics for advanced level, second edition)
If V is a constant the P/T will be constant, V being its volume, P being its pressure and T being the temperature. This is the pressure law.

The pressure law states that the pressure of a fixed volume of gas increases as the temperature increases

For an inflated balloon, squash ball etc. the pressure on the inner surface of the ball is greater than the pressure on the outer surface. The inequality of the forces on unit area compensates for the tension in the wall itself.

When hot, the ball has more energy as the air particles inside the ball are moving faster than if they were cooler, but if the ball is heated too much the rubber particles will break their bonds and start ...

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The pressure law states that the pressure of a fixed volume of gas increases as the temperature increases

For an inflated balloon, squash ball etc. the pressure on the inner surface of the ball is greater than the pressure on the outer surface. The inequality of the forces on unit area compensates for the tension in the wall itself.

When hot, the ball has more energy as the air particles inside the ball are moving faster than if they were cooler, but if the ball is heated too much the rubber particles will break their bonds and start to turn into a liquid.
Rubber is a natural polymeric substance made out of long chains of molecules; these long chains can change shape and sometimes slide past each other when the material is subject to a deforming stress.
Rubber shows little obedience to Hookes Law. (Introduction to advanced physics)

For an inflated balloon, squash ball etc. the pressure on the inner surface of the ball is greater than the pressure on the outer surface. The inequality of the forces on unit area compensates for the tension in the wall itself. (Introduction to advanced physics)
Acceleration due to gravity is 9.81ms‾²
S= ut +½ at²

It is observed that a higher temperature object, which is in contact with a lower temperature object, will transfer heat to the lower temperature object. The objects will approach the same temperature, and in the absence of loss to other objects, they will then maintain a constant temperature. They are then said to be in thermal equilibrium.
Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. (Internet)

Preliminary work

First we had to find out a suitable height to drop the ball from, it has to bounce to a reasonable height so it will make it easier for us to record. First we dropped the squash ball from one meter (at room temperature) It bounced to about 16cm, this measurement is too small and would make all the readings not accurate enough as the smaller the height the greater the error percentage. Kinetic energy and gravitational potential energy are proportional, so the higher the ball is dropped, the higher the ball will bounce. So we dropped the ball from the ceiling, 2.62m, its bounce was 45cm. This reading is more appropriate. We thought about dropping it from the top of the science block stairs but we decided that it wouldn’t be appropriate as taking the ball from the lab to the stairs it would either cool down or heat up, this would make the results more inaccurate. Another idea was to drop the squash ball out of the window, but this would be even worse as it would drop onto an uneven surface and also the weather e.g., the wind would make the results unreliable.

We then thought about the time the squash ball should stay in the water. We heated some water in a beaker with a Bunsen to 65 degrees, held the squash ball in the tongs and placed them in the water briefly. As we heated the water with a Bunsen things were hot we had to think about safety, being careful not to burn ourselves. Then took the ball out and immediately dropped it from the ceiling, the bounce was 1m. The ball was warm. We then decided to keep the ball in the water of the same temperature for one minute. Dropped it immediately and the bounce was 1.10m and it felt warmer. From this we decided to keep it in the water for one minute in the actual experiment. It will be harder to control the same temperature for one minute.

Another thing that we decided to investigate was the lowest temperature we could get the ball to. So we put lots of ice in the beaker of water. The thermometer showed that the water was 5 degrees we thought that this temperature was reasonable for our lowest reading. We also tested the bounce from the ceiling; it was low, but readable.

From this preliminary work we found out that it was difficult to get very accurate readings for the height the ball as it bounced quite fast, so we decided that measuring the bounce to the nearest centimetre would be more reasonable. Also getting the temperature to stay the same during one minute was quite difficult so for each of the readings we will take into consideration an error of 2ºC.

Method

COLD

Set up apparatus as shown in diagram 1.
Test the temperature of the water with the thermometer, if the temperature is not in between the boundary temperature either add more ice, or heat lightly.
Put the squash ball in the beaker of icy water with a thermometer so to keep an eye on the temperature, weight the ball down with the tongs so the ball is totally submerged.
Wait for one minute so the ball can get to the specified temperature starting with 5° and then 10°C adding five degrees each time until you get to 90ºC. Getting the ball to exactly the right temperature will be difficult so add one degree to each side of the specified temperature, e.g. for five degrees getting the ball to four, five or six degrees is acceptable.
Quickly take the ball out of the water then dry it off roughly with a paper towel.
Elevate the ball to 2.62m (the height of the ceiling) and release.
The second person is ready to read the height of the bounce from the meter rule (at eye level to the ball).
Record the height of the bounce.
Get the water to roughly the same temperature by adding more ice, then repeat the experiment from point 3 a further two times. The reason to repeat this experiment is to make the results more accurate. We can appreciate that the results will not be extremely accurate as the bounce is very quick and it will be difficult to measure to say the nearest millimetre so measuring to the nearest centimetre would be more appropriate. Repeating the experiment will lessen the degree of inaccuracy and also show any anomalous results. If you notice any anomalous results redo that reading again.

HOT

Set up the apparatus in diagram 2.
Heat the water to get the desired temperature which is stated on the results table.
When at roughly the right temperature clamp the ball in tongs and place in the water for one minute.
Use the same method from point 5 to point 8 from the cold method.
To get higher temperatures the use of a Bunsen burner is needed, but beware! Everything will get extremely hot so take care not to burn yourself. Heat proof gloves maybe appropriate for the person taking the ball out of the water.

Justification

Using a 100° thermometer is appropriate as in the experiment as the temperature of the water will not exceed 90°.

To make sure that the squash ball is at exactly at the right temperature, I could use a water bath. But in this experiment I do not think that it would be appropriate as the ball will only be in the water for short periods of time and also the temperature doesn't have to be extremely accurate.

The meter rules are appropriate as we are measuring the bounce to the nearest centimetre. It would be too difficult to measure to the nearest millimetre as the bounce is very fast.

Conclusion

From the graph I can see that it has positive collation. It is a straight-line graph so it follows y =mx+c. Where c is the intercept, from doing a best-fit line on my graph, c =3 this shows that when the ball is 0°C its bounce should be about 3cm. I calculated the gradient m (y/x) to find that it is 1.4 or 7/5. The gradient shows height of bounce per °C. Therefore my equation is y = 7/5x +3. So with this equation I could work out what the height would be for other heights, for example the bounce height for 300°C would be 423cm. (Of course this wouldn't be true as the rubber is heated to high temperatures the particles will break their bonds and start to turn into a liquid.

From the evidence that I have gained doing this experiment I have proved that, when the squash ball is hot it has more energy-, as the particles are moving faster than if they were cooler so the bounce is greater. When the squash ball was heated, the air particles in them got more pressurised, when they got more pressurised the particles moved faster and they collided more. Higher pressure meant less deformation energy when the ball hit the ground and more kinetic energy upwards so more G.P.E upwards therefore a greater bounce height. Kinetic energy and gravitational potential energy are interchangeable. Heating the ball to greater temperatures meant the bounce of the ball increased.

This is true as the bounce of the squash ball increased as it was heated. Also, the pressure law states that the pressure of a fixed volume of gas increases as the temperature increases, this was proved, as the ball needed more pressure to bounce higher showing more pressure.

More energy was transferred to the ball at higher temperatures so it had more kinetic energy to start with. When something is elevated off a surface, it is said to have gravitational potential energy and when it is released this G.P.E is transferred into kinetic energy. G.P.E and K.E are interchangeable. So the ball had more gravitational potential energy to start off with so then a greater fraction of kinetic energy was given to bounce back up, hence a bigger bounce.

Evaluation

This experiment was suitable for testing the bounce of the squash ball as it was quite accurate, there was a margin of error in the results so it wasn’t extremely precise, to make it more accurate we carried out the experiment three times so the margin for error was reduced. Also, repeating the experiment we could recognise any anomalous results and redo the reading. Most of the results were in close agreement to each other showing the accuracy. We carried out the experiment with a wide range of temperatures again to make the experiment more accurate, because if we had only tested a few temperatures we wouldn't have fully understood what was happening. The experiment was straightforward and simple to carry out as we had all the apparatus needed and it could be carried out in the lab at school. We could complete the experiment in the given time and we could start it immediately at the start of the lesson. We were asked to find out the effect of temperature on the bounce of a squash ball; this experiment allowed us to do this.

However there were limitations to this experiment that stopped us from getting perfect results every time. We had to measure the bounce height to the nearest centimetre with an error margin of two centimetres as we didn’t have special equipment like a light gate to measure it. Another way to make reading the height of the bounce more accurate would be to film each bounce with a video camera, play back the footage and pause it when it gets to its terminal velocity and then record the height. With this method we could measure the bounce to the nearest milimetre. This would be inappropriate as we only have two video cameras in the school and it would be extremely time consuming. Concerning the strategy we left the ball in the water each time for one minute, this wouldn't be enough time for thermal equilibrium to take place, as work has to be done to get this. (Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow.) But again it would be inappropriate to wait about 30 minutes for thermal equilibrium to take place for each temperature as we had 18 different temperatures to test tree times in a limited time span. The time it took to take the ball out of the water, dry it and drop it could have affected the temperature of the ball. We could have kept it in the beaker of water at the height that we were dropping it from, then the ball would have had less time to cool. This method would have been inappropriate; as it would be dangerous at high temperatures as the risk of burning someone would be greater. Our method for this experiment was realistic and practical.

The main sources of error was random errors like dropping the ball as it was uncertain how the ball was going to bounce, for example it could hit something on the floor and bounce differently. We thought of dropping the squash ball down a plastic tube to get the bounce in the same place every time, but the ball could hit the sides of the tube and affect the bounce height so we decided against changing the method. Doing the experiment 3 times lowered this error. We also had a systematic error as one of the metre rules had a piece missing, although this was rectified before the bounce exceeded one metre.

The margin of error does matter for different heights, for example, there would be more error for lower temperatures as the bounce was smaller than at higher temperatures with bigger bounces. There is an equation to show this: percentage error = error/ actual value x 100. For 10°C the percentage error would be 2/20 x 100 = 10%. For 85°C the percentage error would be 2/122 x 100 = 1.64%. I think that a percentage error of ten percent is reasonable for this experiment because it still shows the effect of temperature on a squash balls bounce clearly with good results.

Glossary