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# Hair Dryer Levitator

This hair-raising experiment will warm you up and blow your mind as you defy gravity with hair!

• Science > Physical Sciences > Year 2 > ACSSU033

## You'll need

• A ping pong ball
• A hairdryer

## Try this

1. Turn on your hair dryer to the highest setting and select the “cool” setting if you have one.
2. Point the hairdryer straight up and place the ping pong ball within the flow of air. Gently release the ball in the middle of the airstream.
3. If you have placed the ball in the right spot, it should float in place. Test your skills and see how far you can tilt the hair dryerto the side before you lose the ping pong ball.

## Further investigation

• Try using a balloon instead of a ping pong ball. Does it work as well? How big can you blow up the balloon before it stops levitating? What happens if you use non-round balloons?
• Try using a bigger ball, such as a beach ball, and a bigger air source, such as a leaf blower

## What's Happening?

The ping pong ball will fly up with the air from the hair dryer until it reaches a point of balance – this is where the force of gravity (which pushes the ping pong ball down) is equal to the force of the air (which is pushing the ping pong ball up).

But why doesn’t the ball go flying off the stream of air? This explanation may reach beyond the year 2 curriculum link mentioned above, but it is included below for completeness.

The ping pong ball stays within the column of air coming from the hair dryer due to the Coanda effect. This is a phenomenon whereby moving fluids stick to surfaces they are moving past. This means that as the air flows past it pushes onto the ping pong ball, but as the stream is passing along all sides of the ball, it pushes evenly on all sides, keeping the ball in the air stream. As you tip the hair-dryer on an angle, this Coanda effect continues to hold the ball in the air stream, until you tip it so far that the force of gravity outweighs the force of the air and the ball falls to the ground.