Spin like an Ice Skater
What you need:
•    a spinning chair, like an office chair

Try this:

1.    Sit on the chair with your arms stretched out to the sides. Have someone spin you around and then bring your arms in. What happens?
2.    Try it again with extra weight in your hands. You can use small hand weights or cans of soup.



Spinning - Arms out
Spinning - Arms In



What’s going on?
The spinning ice skater is a demonstration of conservation of angular momentum. What do all those big words mean? Conservation means that it is always the same. Angular means you are spinning and momentum is a combination of your speed and your inertia (how hard it is to move you). With your arms out, it’s harder to move you, so you go slower. With arms in, it is easier to move you and so you go faster.