Demonstrate Angular Momentum on a Chair
One of the introduction activities to angular quantities, this is a must for the kids to pick up the effects of the ever-popular Conservation of Angular Momentum, or "CAM" for short. There are many variations of this activity, but they all entail the student simulating a skater's rapid increase and decrease of rotation by simply changing the shape of the body.
- Basic: Use an industrial strength spinning stool. Many old schools still have these around. They can have backs to them or not. As long as it is a simple rotating stool, yer cool. Have the kid hold some weights in each hand. My HS boys can usually handle 2 or 3 kgs each hand. Hold arms out horizontally. Spin the kid as fast as you can while still maintining balance. Make sure the kid's feet are tucked in under him/her. If the legs are outstretched, it produces a larger Moment of Inertia and the effect is smaller. Now, once the kid is spinning as fast as you can get him/her, have the kid bring in the arms quickly so the weights are both at the kid's chest. Often, the kid's Rotational KE increases so drastically that he/she falls off the stool!
- Use a heavy-duty "lazy-susan". Repeat the above procedure.
- If one of your kids has EXCELLENT balance, try this in the standing position! It is even more dramatic than on the stool. I wouldn't, however, have the kid stand on the stool... A body flying through the air from a height of a meter or so landing on linoleum covered concrete requires administrative paperwork and lots of clean-up...