Since summer is hot, it doesn't take too much persuading to get my boys outside to do an experiment where they might get wet.
I told our six year old that we were going to fill a bucket with water and that it'd be upside down over his head without spilling. One of his eyebrows went up with skepticism.
But lo and behold, he did it. Here's how.
What You Need
A small pail with a handle
Clothing that can get wet
What to Do
Fill your pail half full of water.
Holding it by the handle, swing it in front of you from side to side like a pendulum. Once you get going at a pretty swift pace, swing the pail with a straight arm in a circular path above your head and all the way around.
If you're going fast enough, the water will remain in the bucket without spilling out!
How it Works
Because of the swift pace with which you're swinging the bucket, centripetal force is present. While you're spinning, a force is applied to the bottom of the bucket to push the water out, but thanks to Newton's Third Law of Motion (every action has an equal and opposite reaction), the water pushes back against the bucket and, therefore, doesn't slosh out.
This great activity came from a wonderful book of science experiments. Check it out!