Results
I am going to work out pressure and predicted hang time using the following formulas.
This is how to work out pressure; P1 is Pressure 1, which is always 1. T1 is Time 1 and T2 is Time 2.
This number changes as you
work out P1, P2 P3 etc.
Eg. P1 = P1, P2 = T2 etc.
P1 x T2
T1
To work out predicted hang time you use this formula. In this formula P1, P2 etc are Predicted hang time.
This number changes as you
work out P1, P2 P3 etc.
E.g. P1 = P1, P2 = T2 etc.
H1 x T2
T1
Analysis
From my graph I can see that the predicted hang time and the actual hang time differ greatly from 293 Kelvin onwards, the real hang time increases quite dramatically where as the predicted hang time escalates only a bit.
From doing this experiment I have found out that when pressure is increased by raising the temperature inside a squash ball, the particles gain more energy and can reform more quickly from its impact on the surface. My actual hang time results show this.
My prediction was correct in the sense that my theory of the particles gaining energy worked. My predicted hang times unfortunately were not correct. They were not a good match to my actual hang time results; I put this down to another variable.
The other variable I believe is elasticity of the squash ball’s material. I believe that if the ball has high elasticity then the deformation (formed by the impact of the ball hitting the surface) of the ball will be bigger and because it is bigger it will reform more quickly and bounce higher.
The energy at the start of the ‘dropping’ process gravitational potential energy, but as the ball speed increases this changes to kinetic energy. When the ball reaches impact, kinetic energy changes to elastic potential energy and a bit of thermal and sound energy. This thermal and sound energy remain at a low constant throughout the rest of the balls ‘bounce back’. When the ball reforms it bounces up and gravitational energy increases to its previous level.
Evaluation
I think I conducted my experiment to a high standard and there were no major anomalous results (except the hang time and predicted hang time results). Each result had an average difference of 7.9 between the next one, this average was brought down drastically by the 2.8 difference between the first two results (38.4 and 41.2).
If I were to make any improvements to the method and equipment of this experiment I would: -
- Change the way the ball was dried as I think a more sophisticated way could be used to prevent human error.
- Use a different way of timing the balls impact to the ground; a touch sensitive timer mat would work well.
- I would try different surfaces on which the ball lands on, this could be thought of as another variable I could develop.
If I were to do this experiment I would change the temperatures to smaller differences i.e. 273 Kelvin, 278 Kelvin etc. to see if I could find an ideal temperature that had a good enough ‘bounce’ to help develop work into elasticity of the balls material.
If I were to develop this experiment further I would test elasticity. To test this I would experiment with a range of different squash balls. I would cut them into equal narrow pieces and use a Newton spring to test how much the piece of squash ball could hold and how long it would take to reform back to its original shape, for this I would use a Newton spring and stop clock.
All in all I think I conducted myself well on this experiment and have learned a lot.
