Conservation of Angular Momentum
Angular momentum is also conserved. If you have ever watched a figure skate spinning, you will have noticed that when she pulls her arms in tight she spins more quickly,and when she stretches her arms out wide she spins more slowly. This demonstrates the conservation of angular momentum. Since angular momentum is a product of rotational inertia and rotational velocity, changing one will change the other. Consider the explains why divers in a tight tuck can spin more quickly when diving.