how to make a hovercraft

WHAT YOU NEED:

- A balloon
- A pop top lid from a drink bottle
- An old CD
- Glue

WHAT TO DO:

1. Take your pop top bottle lid and glue it right over the hole in your old CD.Leave it to dry.
2. Once your lid is securely glued to the CD, blow up your balloon.Pinch the bottom of the balloon so that the air can’t escape and stretch it over the pop top.
3.Place your hovercraft on a smooth surface like a table top and open the pop top lid so that the air from the balloon starts to escape.Let go and watch your hovercraft go!Give it a little push or flick with your finger and watch it glide across your surface.

The Extreme Science behind this:

Usually, if you had a CD sitting on a table top and gave it a push – it would only move as far as your finger pushes it.This is because of friction which is a force that acts between any surfaces that rub together – friction makes it harder for the objects to slide past each other.

In this experiment though, the balloon is letting out air, which escapes out under the CD creating a layer of air between the CD and the table top.This layer of air greatly reduces the amount of friction between the CD and the table top –meaning your CD hovercraft can glide around over the surface when you flick it with your finger!