Investigating the percentage of energy loss of each bounce of a rubber ball

1. HL Physics AssiaChelaghma
Internal Assessment:
Investigating the percentage of energy loss of each bounce of a rubber ball
Introduction:
Rubber balls are made of atoms that are held together in a solid structure. A rubber ball can
have a potential energy due to gravity and a kinetic energy due to its motion.
The potential energy of the ball depends on the strength of the gravitational field, the mass of
the ball and its distance above the ground.
The formula of potential energy is: 𝑃𝐸 = 𝑚𝑔ℎ
Where 𝑚 is the mass of the ball, 𝑔 the gravitational constant and ℎ is the height of the ball
above the ground.
Kinetic energy is the energy of motion; it depends on the mass and on the velocity of the ball.
Its formula is: 𝐾𝐸 =
1
2
𝑚𝑣2
Where m is the mass of the ball and v is its velocity.
When the rubber ball is dropped from a certain height, it loses potential energy and gains
kinetic energy until all the potential energy becomes a kinetic energy. From the first law of
motion we know that:
𝐿𝑜𝑠𝑠 𝑖𝑛 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 = 𝑔𝑎𝑖𝑛 𝑖𝑛 𝑘𝑖𝑛𝑒𝑡𝑖𝑐 𝑒𝑛𝑒𝑟𝑔𝑦
From the third law of Motion, we deduce that when the ball hits the ground, it applies an
opposite force equal the force applied on it by the ground which make it bounce into air. The
diagram below shows the bouncing of the ball:

2. HL Physics AssiaChelaghma
The rubber ball doesn’t bounce to the same original height because some of its internal energy
is lost to air in from of heat and sound.
In this investigation I will investigate the percentage of potential energy loss of each bounce
of a rubber ball.
Research Question:
How does the maximum height of a rubber ball above the ground at each bounce affect its
percentage of potential energy loss in each bounce?
Variables:
Independent Variable:
The maximum height reached by the rubber ball at each bounce. Each time the rubber ball
bounces it reaches a certain height until its velocity is zero then falls down again. The
maximum height reached by the ball will be detected by logger pro sensor.
Dependent Variable:
The percentage of potential energy loss at each bounce. I will calculate it by finding the
maximum height of each bounce using logger pro. Then I will use the formula PE = mgh to
calculate the maximum potential energy. After getting all the potential energies of the
different heights I will calculate the percentage of potential energy loss using the formula:
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑓 ℎ1 − 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑓 ℎ2
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦
Controlled Variables:
 The material of which the ball is made affects its bouncing. Thus, the same type of
balls I used throughout the experiment. The ball is made of rubber.
 The size of the ball affects the air resistance. Thus, the same ball will be used
throughout the experiment.
 The ground surface and the friction force with the ground affect the bouncing of the
ball. Hence, the experiment will be conducted in the same place, on a frictionless
table.
 The initial velocity of the ball should be always zero so that it won’t affect the
bouncing. Hence, the rubber ball will be dropped from rest.
 The angle affects the velocity of the ball. Hence, the ball will be set up at right angle
to the ground and will be dropped vertically.
 The force excreted on the ball affects its bouncing. Therefore, there will be no force
applied on the ball apart from gravity.

3. HL Physics AssiaChelaghma
Apparatus:
 One rubber ball of mass 100g.
 Frictionless table of dimensions 4𝑚 𝑙𝑒𝑛𝑔𝑡ℎ × 3𝑚 𝑤𝑖𝑑𝑡ℎ × 1𝑚 ℎ𝑒𝑖𝑔ℎ𝑡
 Logger pro sensor
 Computer
 Measuring tape
Method:
 Set up the experiment shown below:
 Connect the logger pro sensor to the computer.
 Set up logger pro to give you the displacement of the rubber ball against time.
 Set the rubber ball at height 1.5m.
 Put the rubber ball at right angle to the ground.
 Ask a partner to click collect to make logger pro start collecting data right after you
drop the rubber ball vertically.
Logger Pro sensor
Rubber Ball
Frictionless
Table
1.5m

4. HL Physics AssiaChelaghma
 When the rubber ball finishes bouncing click stop.
 Use logger pro to get the maximum height of each bounce.
 Calculate the potential energy of the rubber ball at each maximum height.
 Calculate the percentage loss in potential energy.
 Plot potential energy loss against the height to get the answer for the research
question.
Method to collect enough Data:
At each bounce the ball will fall from a height differ from the previous height because some
energy will be lost to the surroundings in form of heat and sound.
The range of the independent variables is limited between 1.5m and 0m. The heights will be
determined by the number of bounces of the rubber ball when dropped. I will take in
consideration all the heights of the bounces and calculate the percentage loss in the potential
energy in each bounce.
The experiment will be repeated 5 times for the same initial height (1.5m).