(Adapted from Science Projects in Renewable Energy
& Energy Efficiency written by the National
Renewable Energy Laboratory, published and copyright
1991 by the American Solar Energy Society, and
distributed by the National Energy Foundation.
- Balloons of different sizes
- Masking tape
- 25 feet of thin fishing line (mono-filament
- Plastic drinking straws (one for each balloon)
- Some heavy books
- A 25 foot tape measure
- A pad of paper and pencil for writing measurements
Blow up each balloon,
holding the end closed with your fingers so
it stays full, and have someone else tape a
straw to the middle of the balloons. Let the
air back out of the balloons.
the piece of fishing line and stretch it tight
between the back of two chairs spaced about 20
feet apart. Leave one end with a bow knot so that
you can untie it easily.
some heavy books on the seats of the chairs to
keep them from tipping over.
the fishing line and push the line through one
of the straws with the front of the balloon facing
and bring the balloon and straw back to the other
end (the starting line). Retie the string to the
chair so the fishing line is tight.
up the balloon as much as you can. Pinch off the
end. Then let go of the balloon. Measure how far
it went along the fishing line.
Try another balloon of different sizes, or try
the same balloon blowing it 1/2 way full or 1/4
of the way full. Measure how far the balloon travels.
down each of the balloons type (round, long, small,
large) and how much you blew it up (full, 1/2
way, 1/4 full, just a little) and how far each
of the balloons traveled.
A law of physics says for every action, there
is an equal and opposite reaction. The force of
the air escaping from the balloon and pushing
out the end forced the balloon to travel forward.
This is the same principle used in rockets. Yet,
instead of air...the rockets use rocket fuel.
The air you blew into the balloon became stored
energy. When you released the balloon's end, the
stored energy became mechanical energy moving
Rather than flying all around the room, the straw
and the fishing line kept the balloon traveling
in a straight line. What balloons worked best:
the long skinny ones or the round ones? What happened
when you blew up the balloon only half way or
1/4 of the way?
Do you think air can be used for moving a car?
What about moving an astronaut in space? Can you
think of other things that compressed air can