Planning (P)
For my physics coursework, I have been asked to investigate the factors, which affect the way in which a ball will bounce. I looked into a few different factors, including height of the ball, landing surface of the ball, and in depth, the height from which the ball is bounced. I also looked at how the temperature change takes place while bouncing the ball.
I took my final point further and decided to investigate the temperature of the ball while bouncing. My input variable is going to be the temperature, which I will be changing.
Prediction:
After doing some background research on different types of balls, I found out a reason why balls actually bounce. All balls bounce because of the air and gravity. The air makes the ball bounce. If I bounce a ball in the air, it will not stay up and bounce back down. The reason for this is gravity. If I bounce the ball hard, it will go up high in the air but if I bounce the ball softly, it will not really bounce at all. The reason for this is because balls have elastic in them. ("The elasticity is an objects property of changing shape when the deforming force is moved").
When an elastic ball is bounced on a hard surface, the shape of the ball deforms and the kinetic energy is converted and stored as potential energy. But when the ball returns to its original shape, potential energy is reconverts back to kinetic energy, and this will make the ball bounce. I also predict that while the ball is bouncing it will loose its energy and this is why it slows down bouncing after a little while.
If a ball does not have air inside it, the ball will not bounce well.
With this information, I can predict that if the ball is heated up, it will bounce more than the ball heated up but with a low temperature. Like the ball which has been kept in 25° water, will bounce less than the ball heated up in the 65° temperature water.
Method:
I will first heat up the water at different temperatures, starting from 25° going up to 35°, 45°, 55° and 65°. To heat the water up, I will use this heater, which keeps the temperature accurate once you have picked the temperature. This will allow me to have a fair test, because if I used a kettle then a few minutes later the water can cool down again, which will not give me an accurate results. I will keep the tennis ball in the water for 5 minutes sharply. To make sure the ball is kept ...
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Method:
I will first heat up the water at different temperatures, starting from 25° going up to 35°, 45°, 55° and 65°. To heat the water up, I will use this heater, which keeps the temperature accurate once you have picked the temperature. This will allow me to have a fair test, because if I used a kettle then a few minutes later the water can cool down again, which will not give me an accurate results. I will keep the tennis ball in the water for 5 minutes sharply. To make sure the ball is kept inside the water for exactly 5 minutes, we used a stop watch.
I will drop the ball from the same height - 1-meter. I will place a ruler against the ball, which will help me to measure 1 -meter accurately. I will record how many times the ball bounces while thrown from different temperatures, but the same height.
I will be measuring the number of times the ball bounces while being dropped from the same height but in different temperatures. Like I said, I will put a ruler against the wall, 1-meter long, and throw the ball from that height. I will make sure my results are reliable by doing this experiment at least three times. This will give me a more accurate result.
Equipment and other things:
* Boiler
* Tennis balls
* Electronic thermometer
* Stop watch / timer
To make sure I know what I should be doing in my investigation, I decided to do a preliminary experiment, where I can realise my mistakes and see how to not make the same mistakes in my real experiment.
Below are my results that I got from the preliminary experiment that I did:
Temperature (°C)
Number of times the ball bounces
Room Temperature - 25°C
5
35°C
5
45°C
7
55°C
7
65°C
7
After doing my preliminary experiment, I realised that the temperature dating was not good. I then decided that for my real experiment I will not go up in 10's but instead go up in 20's. So this how my temperatures went, 25°, 45°, 65° and 85°.
On the nest page is a graph that I got from my preliminary experiment:
All this has helped me decide that in my real investigation I will make sure that the temperature will go up in 20's instead of 10's because the temperatures that I have chosen did not give me an accurate result in my preliminary investigation.
Results (O)
In my team, we made sure that we did our experiment safely. To make our investigation fair, we decided to do our investigation more than once; we actually did it three times.
Below is a table of my results:
Number of times the ball bounces
Temperature (°C)
Experiment 1
Experiment 2
Experiment 3
Room Temperature - 25°C
5
5
6
45°C
5
6
5
65°C
5
5
5
85°C
6
6
6
As you can see from my table, my results did not show enough evidence but I did realise at the temperature 85°C, that if I did another test on 105°C, then I would be able to see that the number of times the ball bounces will increase.
I can see form my table that doing my experiment three times gave me an accurate result. There are a few ups and downs in my table but only by one unit. This made my results more predictable. Below I have draw four graphs. Three of the graphs are for each experiment and one is for all three experiments in one. Below is the graph for experiment 1:
Below is the graph for experiment 2:
Below is my graph for experiment 3:
Below I have drawn a graph comparing all three experiments:
Conclusion (A)
As you will see, the last graph I drew contained my results that I got from the investigation.
In this investigation, I have found out that, the number of bounces a ball will give can be influenced by the temperature of the ball. My graph supports me in this, because if you will look at the graph for experiment 1 (below), you will see that as the temperature increased, the number of bounces also increased.
This is the graph for experiment 1, and you will be able to see the increase in number of bounces as the temperature increased. My graph showed an increase in the number of bounces rapidly, his helped me to know that if I ha done another experiment with the temperature going up to 105°, then I would have got a better graph.
As you will see, my predicted graph can be compared with my actual graph from my experiment and I can see hat there is a relationship between them. Both graphs showed an increase in the number of bounces when the temperature increased.
When I compare all three of my graphs, I can see that, all of them gave me three different results.
The first graph gave me a result that was increasing. The number of times the ball bounces increased as the temperature increased.
In the second graph, I can see that there is a pattern that goes up and down by the same numbers. So this did not go with my aim.
The third graph showed an increase, but then decreased again, and then increased again. This can also be a pattern but I cannot say this for sure because I need to do another experiment for that, which should have a temperature of 105°C.
This showed me that not all of my experiment went with my predicted graph. I cannot draw a scatter graph with a line of best fit because my results are not accurate. As you will see below, I have drawn a bar chart which consists of all three results:
Evaluation (E)
Even though my graph for the first experiment matched my predicted graph, I did not get good results to prove my point. I did prove my point but did not have much evidence.
I have thought of a few points where I had gone wrong and if I can get another chance of re-doing my experiment again, I'm sure my results would come out better. Below I have written down what I could have done to improve my point:
* I had kept the balls in temperatures of 25°, 45°, 65° and 85°. In my preliminary results I had seen that my other temperatures did not give me accurate results so I had chosen these temperatures for my real investigation. If I redo my investigation, instead of keeping them in these temperatures I can keep them in temperatures of 25°, 65°, 105°, 145° and 185°. This will give me an accurate result because the higher the temperature the more number of bounces you will get.
* The next thing I will want to change is the ball. After doing the experiment I realised that a tennis ball was not a great ball to do the experiment with. Tennis balls do not bounce as much. So I will use a different type of ball which actually bounces a lot. I would also want to remove the fur of the tennis ball, because I think that the fur is the only thing that prevents the tennis ball from being heated up from the inside.
* After looking at the ball, I also realised that the tennis ball did not get the hot temperature right through it because of the fur. This could be another reason why my results were not accurate.
* If I want, I can also change the height the ball is dropped from, because if I drop the ball from the height of 1-meter, then the ball will bounce more than the ball dropped from a 2-meter height. This is not a good idea, but can change my results and help me prove my point.
These are the main things I would want to change. I'm sure that if I have applied all these to another experiment, I will get an accurate result.
Nitu Kapoor
Science
Bouncing Balls
