Soccer Ball Size
I am doing a project for the science fair at my >>
school. My problem is how does a the size of a soccer ball affect how >>
far it goes when it is kicked. What kind of science should I go to for >>
my research and information?
The size (and thus also the weight) of the ball affect how far it goes.
To shoot a ball, you give it some energy. If the ball is lighter, it will
start at a higher velocity and end up going further. Therefore, if made of
the same material, a small ball is lighter and will go further.
An equally important factor is the air drag, that is, the resistance of air
as the ball moves. You can experience air drag by holding your hand
slightly (not too far, dangerous!) out of a moving car window and feel the
drag force. This force is also increases with size (and with velocity).
So, in a simple way, we say that both air drag and weight of a hallow ball
are proportional to the radius of the ball squared. So, if one ball is 10
cm and another is 5 cm in radius, the weight and air drag on the bigger one
are each 4 times those of the smaller one.
You can look up information on this topic in basic physics books, and also
in books on dynamics and fluid mechanics. An encyclopedia for young
scientists also may be a good start.
By the way, you can make some interesting observations by dropping balls
(metal or others) in a tall column of water (with or without a starting
kick), or by blowing a fan on balls of different size and materials. A
stop watch and tape measure to measure time and distance traveled will you
give some interesting insight.
You will need some assistance from your parents and teachers to try some of
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
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Update: June 2012