A string with a rubber ball on one end is passed through a copper sleeve, and a weight is attached to the other end. Whirl the ball above your head. At a certain speed, the system is in equilibrium. Below the equilibrium speed, the weight moves downward. Above the equilibrium speed, the weight moves upward.
Start the ball spinning at a constant rate. When the weight is pulled downward, the radius of the ball's arc decreases, and the angular velocity of the ball increases.