Make your own simple hovercraft out of an old CD and a balloon. Then watch it glide over the floor on a cushion of air. Make a few and have some races with friends which design outperforms them all?
Suitable for kids aged 5+ with parental supervision
- Old CD (youre not listening too anymore)
- Strong craft glue or super glue
- Pop-top lid from a drink bottle
What to do:
- Ensuring that the pop-top lid is closed, glue the bottom of the lid to the centre of the CD. The base of the lid needs to be completely covering the hole in the centre of the CD. Allow glue to set and dry.
- Blow up the balloon, and pinch or twist its neck to ensure no air escapes.
- Stretch the neck of the balloon over the closed end of the pop-top lid. Try not to let any air escape in the process.
- Place the CD hovercraft on a smooth, flat surface (balloon side facing-up), and give it a push. How far does it travel?
- Now, open the pop-top lid so the air from the balloon can start to escape, and give the craft a push. How far does it move this time?
- Make a few CD hovercrafts and have some races with friends. Try your craft on different surfaces, which works best? Why? Change the design of your hovercraft slightly by using different materials, or larger balloons. How do these changes effect the performance of your craft?
Why is it so?
Air flows out of the pop-top lid when its open, and under the CD. Flowing air creates a kind-of cushion under the CD reducing friction, or rubbing forces. Machine brakes work on the principle of friction to slow things down. Because the CD is weighted and has a very flat surface, air lifts the whole CD off the surface allowing it to glide easily. Air hockey tables work the same way, with a fan under the table pushing air through tiny hole on the tables surface. The flowing air reduces friction and allows the puck to move freely and quickly over the table. And SCORE!