Welcome!
This lesson was made possible by Tracy Trimpe, Havana Junior High, Havana, IL.
Copyright: Trimpe, Tracy. 'The Science Spot." http://www.sciencespot.net/Pages/classphys.html.
Balloon Rally
Objective: By experimenting with several variations (angles), students construct their own
understanding of Newton's Third Law.
Materials: Balloon, Straw (bendable), Tape, Pencil, Pin.
Step 1: Attach a balloon to the end of a flexible straw with tape.
Choose the end that is furthest away from the bend.
Step 2: Push a straight pin through the straw about halfway
between the balloon and the bend in the straw. Fasten the pin in
the eraser of a pencil.
Once you have followed these steps, the students can answer questions on this worksheet.
Those questions are:
1. Blow up the balloon and bend your straw to a 90o angle before allowing the air to escape. What happens?
2. Blow up the balloon and bend your straw to a 45o angle before allowing the air to escape. What
happens?
3. Blow up the balloon, but leave your straw straight (180o angle). Release the air in the balloon. What
happens?
4. Remove the pin and hold on to the straw as you blow up the balloon. Release the straw. What
happens?
5. Explain your observations in terms of Newton’s 3rd Law.
Explanation: Newton's Third law is: For every action, there is a
reaction. When bending the straw 90 degrees (left or right) after
blowing up the balloon, the air pushes the straw and makes it spin,
thus showing that for every action, there is a reaction.
