SUMMARY
In our project we are trying to figure out if
the contents of a football affect its terminal
velocity and how high it bounces.
The terminal velocity of an object is the
maximum speed at which it can travel in
one direction under only the force of gravity.
Our theory is that if we put helium gas
(which is lighter than air) inside a football,
the terminal velocity will be a slower speed
because the football will be lighter, but we
also think that the bounce of the ball will be
increased because it is lighter. We think
that the increase in the bounce will cancel
out the decrease in the terminal velocity
making the ball bounce higher than if the
ball was filled with air.
MEET THE TEAM
Darragh Owens
My name is Darragh Owens. I play Basketball,
Rugby, Gaelic Football and Golf.
I am in my first year at MCS and I love it. My
favourite subjects are Art, Technical Graphics,
English and Science.
When I grow up I would love to be a product
designer or else do something in
advertisement, like ads in newspapers,
magazines and things like that,
Paul Kelly
My name is Paul. I am 13 years old and am
currently attending Moate Community School. I am
in first year and am having a good first year in
Moate. I am from Rosemount, which is a small
village outside Moate town. My hobbies are golf,
soccer, Gaelic and badminton. I have a big interest
in science and hope to have a career in it some day
but my real passion is too be a profession golfer. I
am the youngest of a family of four who love me
dearly.
THE
SCIENCE
WHY THE SHAPE?
The shape of a soccer ball resembles a
buckyball, which was named after an architect,
Buckminster Fuller. It is a polygon with 60
vertices and 32 faces that come together to
make its aerodynamic qualities. The
aerodynamic qualities of a soccer ball are
routinely described by the interaction of the
soccer ball with the atmosphere.
HOW DO THEY SPIN
THE BALL IN THE AIR?
Sometimes in the game, it
is important and necessary
to make the ball curve
around opponents. In this
view of a spinning soccer ball, the closer the air
is to the center of the ball, the faster it travels.
According to Bernoulli‟s principle, the pressure
on a ball can be reduced if the ball is rotating
the same way as the airflow. Bernoulli‟s
principle says that “when speed is high,
pressure is low”, and vice versa. When the
pressure is low on one side of the ball, the other
side has high pressure and this pressure
difference between the two sides of the balls
cause the ball to swerve to one side.
To curve the ball, it must be initially kicked offcenter to create a side spin. If the ball is kicked
with high speed, it will enter a smooth-airflow
help to bring in a large sideways force.
WHAT’S AN EXAMPLE OF THIS?
Roberto Carlos, a famous soccer player, is
known for his amazing shot that curved around
all of the defenders and instantly turned into the
corner of the goal. To get his desired position,
Roberto Carlos kicked the ball with enough
force and includes enough of a roll to produce a
rotation spin on the kick. The speed at which
he could kick the ball had a great influence on
the amount of curvature of the ball. Carlos
kicked it with the outside of his foot, allowing
him to hit the ball hard at approximately 70
mph. The ball then fell into a laminar flow
regime and the ball curved into the goal
WHAT’S NEW
A new soccer ball has come out with improved
dynamics. The traditional ball encountered
problems because of its round shape and
smooth surface. These qualities cause air to
stick to the front of the ball and cause it to slow
down. A new type of ball marketed by Puma
has small dimples on the surface inspired by
the gold ball that are made to redirect air to the
back of the ball increasing the speed about
20%. As the website says, “This results in less
drag and straighter,
smoother flights.” This
new type of ball is
pictured to the right
with its golf-like
dimples. It is priced
online for $100.
WHY DO PLAYERS HATE THE
JABULANI?
During the World Cup several coaches
among them Diego Maradona from
Argentina and goalkeepers, Gianluigi
Buffon (Italy), Sergio Romero (Argentina);
Julio Cesar (Brazil) and Claudio Bravo
(Chile), criticized the „Jabulani‟ and by the
looks of it have now recruited a new critic
that scientifically analyzed its performance
and aerodynamics.
The NASA evaluation was done with US
soccer player Stephen Beitashour from the
US Soccer League San Jose Earthquakes
and the first tests confirmed that the ball
becomes „unpredictable‟ at 72 kilometres
per hour.
Aerodynamic experts from NASA‟s Ames
Investigation Centre said that the weight of
the ball, 440 grams, make Jabulani most
vulnerable to strong impacts generating a
„knuckle effect‟ which means the course
becomes unpredictable.
Airspace engineer Rabi Metha said that
when you have a ball which is relatively
plain and with seams it flies through the air
with little rotation, but air can influence the
channels of the seams generating an
To these details it must be added that the
„knuckle effect‟ the fact that most South
African stadiums are one thousand metres
above sea level, making the Jabulani even
more erratic.
Maybe these NASA conclusions underlining
the unpredictable condition of Jabulani can
come as late comfort for English
goalkeeper Robert Green who could not
contain a short distance shot from US
forward Clint Dempsey, confirming the 1-1
draw; or for the Algerian goalkeeper Fawzi
Chouachi whose slow reaction helped the
Slovakia 1-0 victory or Nigeria‟s Vincent
Envema who was unable to contain a free
kick from Japan‟s Chu-Young thus ensuring
a vital draw for the Asian team.
BACK TO THE PROJECT!
In our project we are trying to figure out if
the contents of a football affect its terminal
velocity and how high it bounces.
The terminal velocity of an object is the
maximum speed at which it can travel in
one direction under only the force of gravity.
Our theory is that if we put helium gas
(which is lighter than air) inside a football,
the terminal velocity will be a slower speed
because the football will be lighter, but we
also think that the bounce of the ball will be
increased because it is lighter. We think
that the increase in the bounce will cancel
out the decrease in the terminal velocity
making the ball bounce higher than if the
ball was filled with air.
EXPERIMENTAL METHODS
1. We got the equipment we needed to conduct
the experiment.
2. We picked a location and time for where and
when we could conduct the experiment.
3. We filled the ball with helium first, and dropped
it 5 times. When this was done we took the air
out of the ball and filled it with air. Then we
dropped it 5 times again like the helium. The
height we dropped them from was 14 feet.
4. We recorded the height the ball bounced using
a long stick and looking at the replay on the
camera.
5. We also used Logger pro software to make a
more accurate calculation of the highest point
of the balls bounce and its velocity.
When we were doing the above steps, it was
important to keep the following constant:
 It was the same day and the same weather
conditions.
 The amount of gas in the ball was the same for
both.
 We threw the ball from the same height and
position and also the same person throwing the
ball.
RESULTS
Height and velocity of bouncing ball using Video Analysis in
Logger
Pro
RESULTS
Height of
bounce
Ball filled
with air
Ball filled
with helium
2.40m
2.15m
2.60m
2.33m
-10.11m/s
-9.61m/s
Manual reading
Height of
bounce
Logger Pro
Maximum
velocity
Conclusion
The results show the ball filled with air hit the
ground fastest but didn‟t bounce as high, and
the ball filled with helium however hit the
ground slower but bounced higher than the air.
Our hypothesis was that the ball filled with air
would fall faster than the ball filled with helium
but the ball filled with helium would bounce
higher than the ball filled with air.
We used the Logger Pro Movie tracking to get
more accurate results.
Over all the experiment was successful.
Acknowledgements
References
Google Images
Wikipedia
The Joke Shop in Athlone
People we would like to thank
 Kieran Doyle (Darragh‟s Grandad)
 Conor Owens (Darragh‟s Dad)
 James Kelly (Paul‟s Dad)
 Ms. Mandal