Method:
1. One person will drop the ball from a height of 100cm. I will measure the 100cm from the floor to top of the ball. A clamp and stand will hold the metre rule.
2. As the ball hits the ground and bounces up I will hold my hand level with the top of the balls top height. I will make sure that my eyes are level with the height of the ball.
3. I will then record these results and repeat the test at different heights.
4. Because each test doesn’t take long to complete I have time to then extend and try a different surface that the ball lands on.
I will make measurements in cm. These measurements will be made when the ball reaches its peak height after bouncing. I will try and made sure these measurements are accurate by standing side on with the metre rule.
5. Once all the measurements in the first exercise are taken, I will repeat the test again and again. Once I have each height recorded three times, I will take an average of the measurements. I will then be able to make a table and graph.
The variables in my tests will be:
- The height in which the tennis ball is dropped from.
- The surface that the ball lands on.
Other variables such as a change in the size or weight of the ball will not be changed.
Prediction:
I predict that the height after the bounce will be lower than the height the ball was ordinary dropped at. I predict this firstly because if a force is passed on over a distance, then work has been done. That means energy has been lost.
Gravitational potential energy is what the ball will have. When it is dropped, the energy can then act, moving the ball to the ground. It is aiming to head towards the core. But, as the ball falls, gravitational potential energy no longer acts on the ball; kinetic energy does until the ball hits the floor.
The ball falling will increase in velocity when it hits the floor. It will accelerate.
The formula for calculating the gravitational potential energy of an object is as follows:
Ug = mgh
Where Ug is gravitational potential energy
m is the mass of the object
g is the acceleration provided by gravity, which we will give a value of 9.8 m per second per second.
H is the height the object is above the ground.
Fair Test
I will make sure that my experiment is fair by not changing or moving the metre rules during the experiment. I will anyone change the height that the ball is dropped from. I won’t change for example the size of the ball, or the surface in which it lands on.
OBSERVATIONS
Table of results:
I didn’t test the ball dropping from the height of 10cm because that would have made the test unfair. The tennis ball is of a height of 7cm
I best way of recording my results was by putting them firstly into a table and then plotting a scatter graph with the results. The graph will be the best way of showing my results. All the measurements I have recorded are in my table and on the graph. There were no results that I thought were “wrong”, but I have drawn a line of best fit to make the graphs results clearer. When taking the results, I repeated the experiment all in all three times. Then I could take an average of the tests. The average results were used in the graph. I did this to enhance the experiment and the graph. My results are much more accurate because I repeated the experiment. If I did the test again, I could always improve the test by repeating it over and over.
I am now able to answer:
1. How much energy is “lost” in a bounce?
There is a clear pattern in my results. I can see this from my table and graph.
If the ball was dropped from 200cm for example, to can find out the lost distance in the bounce by taking the height after one bounce off the ordinary height.
200-87
=113cm, 113cm was lost in the bounce.
113/200
=57% of the height lost after one bounce
If I look at lots of results, I can get a much more accurate answer.
2. What does this lost bounce energy depend upon?
