2. Table tennis ball
3. Tennis ball
4. Rounders ball, I think the Table tennis ball will be bouncier than the Tennis ball because the tennis ball’s surface is made of a furry material which, I think, is going to make it more difficult for it to bounce. I think this order will be repeated for the first two experiments, but I do not think that the compressibility results will follow the same pattern because I do not think that the compressibility of a ball will change its bouncing skills.
To make my experiments safe, I will make sure the balls are only bounced for the experiment and are dropped not thrown to the floor. I will be using a G clamp to measure the compressibility of the balls, and we will have to be very careful with it. Comparatively, this is a safe experiment because it does not require anything potentially dangerous. To keep it a fair test we will make sure the metre stick is perpendicular to the floor when we measure the height, we will test every ball on the same surface because the floor surface plays an important role in how the ball bounces. The balls will be dropped freely not thrown as this will affect how the ball bounces and the same person will bounce the ball every time to make sure it is dropped in the same way. The person looking to see how high the ball bounces or counting the number of times it bounces will sit on the floor so that there are parallel to the metre stick and can see the reading without angle distortions which would occur if they looked at it from above. The most important factors are that I make sure it is a fair test and take accurate measurements.
Method: Here is a list of the apparatus that we will be using: Tennis ball
Table Tennis ball
Golf ball
Rounders ball
Two metre sticks
G clamp
We are going to conduct three separate experiments – one to measure the height to which the ball bounces having been dropped from different heights, another to count the number of times the dropped ball bounces, and another to test the compressibility of each ball. For the first experiment, we will use two metre sticks, one above the other to reach a height of 2 metres. We will drop each ball from different heights and record the height to which they bounce back up. To give a reasonably wide range of readings for this experiment, we have decided to the balls form the heights of 0.5m, 1m, 1.5m and 2m. For reliability, we will repeat every height twice with each ball, which should give us quite accurate readings, and there will be 8 readings altogether, which satisfies the minimum of 6. For the second experiment, we will count the number of times that the different balls bounce having been dropped from the same height, we decided to use the height of 1m for this experiment as it is the one that will be easiest to work with. For the third experiment we will use a G clamp by putting the ball inside it, adjusting the clamp so that the ball is held loosely in it and then count the number of half turns of the clamp-adjusting knob that are possible. We decided to count half-turns because it gives a more accurate and easily interpreted result.
It is possible to use common knowledge in this experiment – I know that in tennis, the ball needs to bounce but not bounce too high because that would make the game too easy, in Golf, the ball needs to be very bouncy because it needs to bounce on a very soft not resilient and surface – grass, in Rounders, the should bounce as little as possible so that is it hard to catch for the other team, and in Table Tennis, the ball should bounce a lot to make hitting it more difficult. Using this information, we can see that the balls used for Table Tennis and Golf should, in theory, be the most bouncy, however I believe that the Golf ball should be the most bouncy because, unlike the Table Tennis ball which is used on a smooth rigid surface, it must overcome the bad surface and still bounce.
I have also collected some evidence from secondary sources. I have found out about Hooke’s Law, which states, “The deformation of a material is proportional to the force applied to it, provided the elastic limit is not exceeded”. This is relevant to my ball experiment because according to Hooke’s law, when each ball hits the ground it will deform according to the force applied to it. I think that in this case the force applied will be the upthrust of the floor on the ball, which is why the floor surface is such an important factor to be considered. The upthrust is dependant on the rigidity of the floor and how hard the ball is thrown which is why we have to drop it in the same way every time to make it a fair test. I have also found some more detailed scientific information of what happens when the ball is dropped. The source of energy has conventionally been potential energy derived from allowing a weight to fall a measured distance under gravity. The height is a measure of Kinetic energy, which is related to the square of the velocity. This means that it is possible to work out the height to which a standard ball will bounce if the velocity is worked out, however it is very difficult to measure the velocity of the ball accurately using classroom equipment.
Obtaining Evidence:
Here are our results for the first experiment – where we dropped the balls from different heights.
The ‘number of bounces’ experiment results:
Compressibility experiment results:
We used a wide range of readings and tested three different aspects of the ball’s bouncing abilities. We repeated every reading to give us more accurate results.
Analysing and considering evidence: From my results from the first experiment I can see clearly that the Golf ball bounced higher than the other ones, there is an obvious pattern in the results. There is an evident relation between the number of bounces and the heights of the first bounce, which means that these two factors affect the bounciness.
I have decided to put the balls in order according to my results to establish the patterns and see whether all three experiments are relevant to the task.
From the first experiment the order of balls that bounced the highest is 1. Golf ball
2. Table Tennis ball
3. Tennis ball
4. Rounders ball
From the results of the second experiment, I see that the order for the balls, which bounced longest, is
1.Golf ball
2. Table tennis ball
3. Tennis ball
4. Rounders ball
And from the results of the compressibility experiment, the order for the most compressible balls is
1.Tennis ball
2.Rounders ball
3.Golf ball
4. Table tennis ball
I can see that the order is repeated fro the first two experiments, however the order for the compressibility experiment is completely different and I therefore assume that the compressibility of a ball is not an important factor in the ball’s bouncing abilities. My predictions were correct – the Golf ball bounces best due to its tough surface, which does not deform much when force is applied to it and therefore does not waste its Potential elastic energy on changing shape but uses it to bounce back up. The Rounders ball is made of soft leather and therefore deforms a lot when force is applied and is also quite floppy which is why it does not bounce well. My results link in with my prediction and prove it – I have shown that the height of the bounce and the number of bounces are good proponents of a ball’s bouncing abilities because the results match each other, however the compressibility is irrelevant and does not affect the bouncing skills of a ball.
I have calculated the averages for my first experiment to help me analyse the results.
Now I can plot a line graph using this information.
The lines of best fit are supposed to go through the origin but according to the pattern they don’t so I stopped them. The graph shows that our results follow a pattern and show which ball bounces best.
Evaluating: I think my results are reasonably reliable as we repeated every reading and they show a clear pattern, which coincides with my prediction. We looked at three different aspects of the balls’ bouncing skills and therefore got a wider outlook of it than we would have if we had just measured one aspect. I think the way we conducted the experiment was quite suitable although I would have liked to look at other variables to get a wider picture. I feel that we could have used a more accurate way of measuring the heights and counting the number of bounces because there were some flaws in our reaction times and the last few bounces that the balls made were very low and fast and therefore difficult to count. However the methods we used were the simplest and most accurate considering the time and equipment available. I feel there was no need to test any more heights in the first experiment because we got sufficient data with the ones that we chose. I think we spent our time sensibly and performed all the experiments planned. The information that we gathered is quite sufficient to make come to a conclusion that the Golf ball bounces best. There were no abrupt anomalies in our results – they all followed the pattern.
