Physics Squash Ball Investigation
To investigate how the rebound of a squash ball is affected by the
I predict that the rebound of the squash ball will increase as the
temperature increases, but only to a certain extent, and after that
the rebound of the squash ball
will decrease as the temperature
According to the 'Pressure Law,' pressure of a fixed mass of gas is
directly proportional to its absolute temperature if the volume
P = Pressure
T = Temperature
1P âˆž T
P = constant*T
P/T = constant
Pressure will increase as the temperature increases, as they are said
to be proportional, because when a gas (i.e. in squash ball) is
heated, the average speed of the moving particles, in this case
molecules, increases. If the volume of the gas is to remain constant,
referring to the 'Pressure Law,' its pressure increases due to more
frequent and more violent collisions of the molecules with the inner
wall of the container
(i.e. the squash ball).
'Boyles` Law' states that the volume of a fixed mass of gas is
inversely proportional to the pressure provided the temperature
2PV = constant
PV = constant
For cases in which P, V and T all change from P1, V1 and T1 to P2, V2
P = Pressure
T = Temperature
V = Volume
P1V1 = P2V2
For example, if the volume of a fixed mass of gas is halved by halving
the volume of the container, the number of molecules per cm3 will be
doubled. There will be twice as many collisions per second with the
walls of the container, i.e. the pressure is doubled. This relates to
our experiment, because I think when the ball is heated, it will
become more compressible, therefore at the point when it will hit the
surface of the table, it will be compressed more easily (while the
temperature, being the variable, also increases at equal intervals).
Therefore the volume would decrease and the molecules within the ball
would collide faster and frequently, thus there will be more pressure
at that point and the ball would 'pop' back to its original spherical
shape with more force causing the balls upwards rebound to be
stronger. Due to this, I think the height of the rebound would
increase, as the ball will become more susceptible to distortion.
Overall, to explain this point, it could be said that:
Rise in temperature.
Molecules collide faster and more frequently.
The ball is more susceptible to deformation.
Later, I think, after the ball reaches its critical temperature, the
height of the rebound will begin to decrease, as the temperature goes
up. The drop in the height of the rebound might be affected by few
a) According to what material it is made of, its molecules may melt
and reduce the height of the bounce. (Approximately at 250-300Â°C)
b) Depending on how good of an insulator the material of the ball is,
will also affect the height of the rebound. Good insulators of heat
would mean that the ball would bounce higher than a ball made up of a
poor insulator of heat, as it will not loose the heat energy more
c) Depending on the molecular structure of the material, it may also
affect the height of the rebound. The material of the ball could allow
a lot of 3'space for air molecules, which would result in an increase
in air pressure'. The higher the air pressure, greater the rebound
The graph might look something like this:
Prediction 2(Ext.): How the initial height of release affects the
height of the rebound.
I think that the higher the initial height of release is going to be,
the higher the height of the rebound is going to be, because as the
ball will travel down, it will have more time to gather speed if
dropped from a higher height due to the acceleration of gravity and
this will increase the height at which the ball bounces back up as the
ball will bounce up with a greater force. I think the graph will
increase uniformly and it is going to be linear as there would be no
rebound to measure if the ball is dropped from 0cm, as there is no
distance to fall through. I think that most potential energy (in %) is
going be consumed, during the rebound of the ball, when dropped from
highest initial release and vice versa (i.e. least % lost). The energy
that is going to be lost is going to transfer to sound and heat
energy, which would be wasted. I think that at a certain release
height, the ball will undergo its maximum disfiguration upon contact
with the ground. Additional increases in drop height will not increase
the disfiguration. Therefore, I think there is a limit to the amount
of energy that can be stored and the shape change produced by the
impact, though the ball might reach terminal velocity before this
happens. The graph might look like this (for only the first few drop
1) We first attached a one-meter rule onto a clamp stand, but later we
changed it the apparatus as it is shown on the diagram. (By taping a
70cm length of paper onto the wall)
2) We heated the squash ball to 100Â°C, in a water bath, for two
3) We dropped the ball, perpendicular to the floor it was going be
dropped on, from a height of 50cm. (With the aid of the measuring
length of paper attached to the wall)
4) We observed the result by looking at the bottom of the ball.
5) Then we jotted the results down onto a table of results.
6) We repeated Step 3 thrice, in order to obtain a good range of
7) We worked backwards, going down in temperature, at set intervals.
(10Â°C decrease of temperature each time), as it was easier and it
8) We repeated Steps 2, 3, 4, for each temperature.
Method 2 (Extension): How the initial height of release affects the
height of the rebound.
1) We heated the ball up to 50Â°C, in a water bath.
2) We dropped the ball from different initial heights of release.
3) Observed the height of rebound by reading off from the bottom of
4) We started from 100cm and eventually decreased our initial height
of release by 25cm each time. We got four readings.
5) We did three trials for each height of release.
6) We repeated Steps 1, 2, and 3 for each initial height of release,
keeping the temperature constant at 50Â°C.
To ensure a fair test, a few things were taken in account:
1) We used the same ball throughout the experiment to make the test
2) We held the ball at 50cm to test it at and then we let go of the
ball, applying no force and letting gravity pull the ball down to the
3) The same person read the numbers from the ruler, from the bottom of
4) We used the same table with the same surface as different surfaces
have different smoothness and changing the surface half way during the
experiment would have made the test unfair.
Method 2 (Ext.):
1) We used a constant temperature figure, 50Â°C.
2) We used the same surface.
1) We made sure that the ball was dropped perpendicular to the surface
(at which it was being dropped at), to obtain an accurate rebound, but
at times it was not as accurate.
2) We did not touch the ball by hand, but by tongs, after warming it
as heat energy from our body could have been absorbed in, by the ball.
3) Did three trials to give us more accurate and reliable results.
SAFETY PRECAUTIONS TAKEN:
1) We wore goggles during heating the ball.
2) We did not touch the ball.
3) Whilst experimenting with the ball, we turned the Bunsen burner off
when it was not being used.
First Trial (cm)
Second Trial (cm)
Third Trial (cm)
Initial Release Height (cm)
First Trial (cm)
Second Trial (cm)
Third Trial (cm)
The graph shows a non-linear, but uniform relationship between the
temperature and the height of the rebound: As the Temperature
increases, so does the height of the rebound. I think my prediction is
correct, according to the 'Pressure law' combined with 'Boyles' Law'
(Look back at flow diagram), but the graph does not look like the
graph I predicted. I think this is because I need more readings of
heights of the rebound against the temperature increase, as I think
100Â°C, was not enough. Maybe if I had more readings, I could have had
more results to produce a better conclusion. This is because the
molecules that the material (of ball) is made up of will eventually be
affected by the increase in temperature, causing the ball to melt.
The graph shows that the relationship between the initial height of
release and the height of the rebound is linear, and uniform: the
greater the initial height of release, the greater the height of the
rebound. At a medium drop height, 50cm, the ball bounced back the
greatest percentage of its release height, 22%, therefore the greatest
percentage of potential energy was conserved during the rebound
whereas in my predictions I thought that the highest drop height would
consume the most potential energy during its rebound.
My predictions were mostly correct. Refer back to predictions.
Looking at my results I can say that they were quite reliable and
accurate. I can say that looking at my results, when I repeated the
results, they were quite similar. I think that I did the experiment
quite well, although I found it slightly difficult to spot where the
ball bounced to and to improve my reading skills, I think I should do
about 5-6 trials per temperature rise. During the experiment, we
changed our apparatus from using a ruler, to a paper, with the
measurements (cm), and this was done to make the experiment more
accurate and we looked straight to avoid parallax error. To improve
the experiment I could use equipment like lasers, cameras etc, to
improve the accuracy of the reading (height of the rebound). To
enhance my experiment, I could experiment with higher temperatures, to
see how the ball is affected. (Either melt or stop bouncing higher,
i.e. height of rebound could decrease)
My results were quite accurate, and I'm satisfied with them, but I
think that I should have had experimented with more initial heights,
so I could get a more accurate medium point, and to see if it is still
the same, for the 'medium height' drop to conserve the most P.E, from
as much as it started from, and to lose the least. Overall I think it
was an exciting and knowledgeable experiment.
1 & 2: GCSE PHYSICS
TEXTBOOK (FROM SCHOOL)