Construct a balloon- powered pinwheel.
BY: John Hartsfield, NASA Glenn Research Center
BY: Roger Storm, NASA Glenn Research Center
- Wooden pencil
with an eraser on one end
- Sewing pin
- Round party balloon
- Flexible soda
- Plastic tape
- Inflate the balloon
to stretch it out a bit.
- Slip the nozzle
end of the balloon over the end of the straw farthest away from the
bend. Use a short piece of plastic tape to seal the balloon to the straw.
The balloon should inflate when you blow through the straw.
- Bend the opposite
end of the straw at a right angle.
- Lay the straw
and balloon on an outstretched finger so that it balances and mark the
balance point. Push the pin through the straw at the balance point and
then continue pushing the pin into the eraser of the pencil and finally
into the wood itself.
- Spin the straw
a few times to loosen up the hole the pin has made.
- Blow in the straw
to inflate the balloon and then let go of the straw.
The balloon-powered pinwheel spins because of the action-reaction principle
described in Newton's Third Law of Motion. Stated simply, the law says
every action is, accompanied by an opposite and equal reaction. In this
case, the balloon produces an action by squeezing on the air inside causing
it to rush out the straw. The air, traveling around the bend in the straw,
imparts a reaction force at a right angle to the straw. The result is
that the balloon and straw spins around the pin.