Tuesday, June 30, 2009

30 Second Science - Bernoulli's Principle

My children have seen demonstrations of Bernoulli's principle at children's museums here and there, but I like to repeat a few basic experiments at home to keep them from forgetting about it, as time passes. Simply stated (and I do mean simply), Bernoulli's principle is that moving air creates low pressure. It is the principle behind the idea of lift for airplanes, and gliding birds.

It can be demonstrated very easily with a hair dryer, and a light weight ball, such as a ping pong ball (though balloons or other light balls, like those plastic ball pit balls, work too). Just point the hair dryer up, turn it on using the coolest setting, and place the ball gently into the stream of air.

You can place more than one ball at a time into the air.

Because the air flow is creating lower pressure than the air outside of the flow, the higher pressure will push the ball back into the air stream if it starts to move to the side. You can tilt the hair dryer from side to side, and the ball will remain in the air stream, until you tilt enough, that the force of gravity overcomes the force of lift.

If you do not have a blow dryer, you can use a drinking straw and lung power.

There is also a kid friendly explanation of the principle, and a printable paper airplane template, for further demonstrations, at www.fatlion.com/science/paperairplanes.html.

It's great to be a homeschooler.

No comments: