Balloon Rocket
Word of the day: push
“We're going to launch a rocket across the room. Fuel: air.”
Grab
- a balloon
- a long string (about 3 m)
- a straw
- tape
- two chairs
A grown-up blows up and handles the balloon. Pick up popped pieces right away; they're a choking hazard.
Do
- Thread the string through the straw. Tie the ends to two chairs so it's tight.
- Blow up the balloon (you do this), pinch the end, and tape it to the straw.
- Countdown 3, 2, 1, let go. Which way did the air go? Which way did the rocket go?
- Try a little air vs a lot of air.
The big moment
Countdown, then let go.
Ask (guess first, then try)
- The air went backward. Which way did the balloon go?
- More air, farther or shorter?
What's going on (for you)
When the balloon pushes air out the back, the air pushes the balloon forward. Every push has an equal push back (Newton's third law). Real rockets work the same way, with hot gas instead of air.
If they want more
Tilt the string up to make it climb. Push off a wall on a rolling chair: you push the wall, the wall pushes you.
Look it up
Wikipedia: Newton's laws of motion