To make a balloon rocket you need a balloon, a drinking straw, some tape and some paper or card to make the fins.
- Cut the end off your balloon and tape the opening around one end of your straw. make sure no air can escape between the balloon and the outside of the straw.
- Cut out three fin shapes and attach them to the other end of your straw. Make sure you leave enough room for your mouth to blow up the balloon.
- Blow up the balloon and let go!
The balloon is moved forward by a force called thrust. This is a push that moves the balloon forwards. This comes from the energy of the balloon forcing the air out.
You could investigate these questions using your rocket:
Does the shape of the balloon (the round ones or the thin ones) change how far or how fast the balloon travels? Does the shape of the fins make a difference? What is the best shaped fin? What is the best material to use to make the fins?
If you have space in your house or garden, you could try making this rocket (click here for instructions).