How does the air pressure of
a basketball affect the height
of its bounce?
Jose R. Sanchez
Jonathan Ryberg
Chris Weisman
Introduction
 Purpose: Ball bounce and air pressure is
important for basketball because:
 1. Not enough: Dribbling is practically
impossible.
 Too much: The ball will bounce too
much.
Introduction
 How does the air pressure of a
basketball affect the height of its
bounce?
Hypothesis
 If we decrease the amount of air
pressure inside the basketball, then it
will decrease the bounce height
because we are increasing the amount
of surface area hitting the ground and
thus spreading the energy over a larger
area.
Materials List





Basketball
Air Pump with needle and gauge
2 meter sticks
Video Camera
iMovie application
Experimental Procedure
 Tape two meter sticks against a wall
 Use a marker to show the lengths at 50cm,
100cm, and 150 cm.
 Use the air pump and gauge to determine the
basketball is pumped to 8 psi.
 Choose a constant (242.6cm) Drop Height
Experimental Procedure
(cont.)
 Drop the ball from the drop height
 Use the video camera to record 3 trials of bounce height
 Repeat steps for 4, 6, 10 and 12 PSI using the gauge.
 Upload the video to iMovie
 Use iMovie to slow down the video to determine the bounce
height
Our Set-up
Experimental Parameters
 Independent Variable: Air Pressure
(PSI)
 Dependent Variable: Rebound Height
 Constants: Release Point, Floor.
Results
4 PSI
6 PSI
10 PSI
12 PSI
120.3
8 PSI
Control
160.67
Avg.
Rebound
Height (cm)
80.3
168.3
169
Rebound
Ratio
.33
.495
.66
.69
.70
Results
Air Pressure (PSI) vs. Rebound Ratio
0.8
0.7
0.7
0.69
0.66
Rebound Ratio
0.6
0.5
0.5
0.4
Series1
0.33
0.3
0.2
0.1
0
0
2
4
6
8
Air Pressure (PSI)
10
12
14
Conclusion
 The data we collected does support our
original hypothesis.
 Not only does it support our hypothesis, but
the data also provides some additional
information. According to our data, as the air
pressure in the ball increases beyond 8 psi,
the amount of rebound ratio is not affected
as much.
 However, as we decrease the air pressure so
that it is less than 8 psi, the bounce height is
affected is much more.
Conclusion:Science Content
 The amount of air molecules increases as the
amount of air pressure increases. Therefore,
the air molecules will have less room to move
when the ball hits the ground.
 According to Newtown’s 3rd Law of Motion,
as the ball hits the ground there is an equal
and opposite force pushing the ball upward.
Sources of Error
 Release Mechanism - Human Error
 PSI not exactly at predetermined level
Further Questions to
Investigate
 How does temperature affect the rebound
ratio of a basketball?(Internal energy of the
air molecules)
 How does the surface affect the rebound
height?
 Which material of the basketball is the best?