CD balloon hovercraft

Science Concept

Friction

Special instructions

The hovercraft will glide across the table until it runs out of air.

Teachers should conduct their own risk assessment of this activity.

Materials

• Old CD
• Pop-top lid from a drink bottle
• Craft glue
• Balloon

What to do

1. Close the pop-top lid and glue the base so the lid covers the hole in the centre of the CD.
2. Blow up a balloon and pinch the neck so that no air can escape.
3. Stretch the neck of the balloon over the pop-top.
4. Place the CD hovercraft on a bench top and push it . How far does it move?
5. Open the pop top lid and push the hovercraft. How far does it move this time?

What's happening?

At first, the CD does not move very far when pushed because there is a lot of friction between the CD and the bench top. When the pop-top lid is opened, air flows out of the balloon, down through the pop-top and under the CD.

The CD is evenly weighted and has a very flat surface so the air lifts the entire CD off the surface of the table. The layer of air between the bench top and the CD greatly reduces the friction between the two surfaces so the CD hovercraft can glide easily across the bench.

Challenge your students to investigate how far the hovercraft will travel on different surfaces. Can they control how hard they push it each time?