Angular Momentum

Demonstration that my mechanics lecturer did......

He stood on top of 2 pieces of boards that can swivel, then he twisted his hips around in an attempt to spin - this did not work.
He took a bicycle wheel, dangled on a string and spun the wheel - he began to spin in opposite direction from the direction which the wheel is spinning.
Amazing.
Conservation of momentum.

Then he held a pair of 5 kg weights and extended his arms and got on the spinning boards. When he retracted his arms and brought the weight closer, he began to spin so much faster. Well, then he got thrown off due to centrifugal force but that is besides the point.

Again conservation of momentum.

heh.