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# Summer Brain Games

## Experiment: Balloon Racers

Make your own breeze on a hot day and learn about Newton’s third law of motion at the same time. Build balloon racers and explore the idea that for every action, there is an equal and opposite reaction. Challenge someone to a race, experiment with different types of balloons, even make your racer into a Chicago “L” car!

### Materials

String
Balloons (long, skinny ones work best)
Straw
Tape
Binder clip
Scissors
Chicago "L" car template (PDF)
Crayons or markers
Craft stick

### Instructions

1. Cut a long piece of string (at least 8 feet), tape one end to a wall and thread a straw on the string.
2. Blow up a balloon, close the end with a binder clip or clothespin, and tape it to the straw so that the neck of the balloon points in the opposite direction the balloon will travel.
3. Hold the string so it’s parallel to the floor, or even tape the other end to another wall.
4. Position the balloon racer at the end, remove the clip and watch it go!
5. Turn your racer into a Chicago “L” car by cutting out and decorating the template. Tape it together with a craft stick in the middle for support, then tape it to the straw above the balloon.
6. Set up two string “racetracks” next to each other and challenge someone to a race! Experiment with different balloons, or try making the racer go up a steep incline.

### What's Happening?

As air rushes backwards out of the balloon, it pushes the racer in the opposite direction with the same amount of force. This is Newton’s third law of motion at work – for every action, there is an equal and opposite reaction.