Tuesday, August 10, 2010

More Fun With The Bernoulli Effect

When you're tired of floating ping pong balls above your hairdryer, you might enjoy this experiment from Robert J. Brown 200 Illustrated Science Experiments For Children.

Take one of the ping pong balls, and tape a piece of string to it.

Turn the water on in the sink, not too strong, but so it's flowing steadily. Holding the end of the string, let the ball dangle down, and touch the water.

Then, slowly move the end of the string, straight back. You will feel the ball clinging to the water, and be able to move the string outward, to quite an angle, before the ball breaks free of the stream.

This is because of a combination of the molecular adhesion between the ball, and the water, and the Bernoulli effect. The pressure of the water moving around one side of the ball, is lower than the air pressure in the room. So when the ball starts to move out of the water, the air pushes it back in with enough force, you can feel it at the other end of the string.

It's great to be a homeschooler.

1. Very interesting. I love this experiments that seem almost magical. I think I would have loved physics a lot more if it was more hands-on in school.

2. Very cool! I remember learning about the bernoulli effect but never in this way!

3. Who ever tires of floating ping pong balls?

Okay, so that would be a cool diversion as well.

4. You keep coming up with them! One cool experiment after another! Keep 'em coming, 'cause I am takin' notes! :)

5. I agree with the comments before mine - physics should have been hands on in school, I vaguely remember the Bernoulli Effect, and who ever tires of floating ping pong balls?

Fun! Fun! Fun!

6. That's so neat!!