Bernoulli's principle:

The pressure of a moving gas decreases as its speed increases.

That was the theme for last nights Webelos meeting. The boys are working on their Scientist badge and we'll be doing experiments for the next 4 meetings. I explained lots of examples - the lift of air on an airplane wing - a curveball - then we tried several 'experiments' to prove how the pressure of a gas changes.

We balanced a ping pong ball over a straw. The Man-Cub kept his ping pong ball going until his breath ran out - I thought about using a hair dryer for this one as it would last longer - but this was more fun...

We also had two ping pong balls on strings and when you blow between them they come together instead of apart but I didn't get a picture of that one.

Then we held a lighted match behind a business card and blew and the flame comes toward the card not away from it.

Then we put a piece of cardboard on a pin and put the pin into the center of a spool of thread and then blew on the top of the spool - the air rushing out of the spool creates a low pressure area and the surrounding air pushes the paper against the spool - all of these experiments were pretty amazing and we all had fun trying them.

Luckily we meet in a church - so the boys were able to practice for Scout Sunday - where they will be the ushers and the communion assistants.