Here's a neat experiment you can do at home. All you need is a blow dryer, and a ping-pong ball.
Take the dryer and point it up. Now turn it on. Now place the ping-pong ball about a foot over the nozzle of the dryer. Look at that! The ping-pong ball floats in mid-air!
Once you have the ping-pong ball hovering over the dryer, try tipping the dryer to one side a little. You'll find that the ball stays hanging in the air even when the dryer is tipped at an angle. It looks as though gravity is suspended!
What's actually happening, though, is called Bernoulli's Principle. Bernoulli's Principle says that fast-moving air has lower pressure than slow-moving air. So the fast-moving column of air coming off the blow dryer has less pressure than the air around it. The ping-pong ball bounces off the higher-pressure air in the room and stays inside the lower-pressure column of air coming off the dryer. Even when tilted to the side!
Read More:
Secrets of the Universe (Atheneum)
