A ball balanced on a vertical rod is an example of

A ball balanced on a vertical rod is an example of unstable equilibrium. In physics, equilibrium is classified into three types: stable, unstable, and neutral. Unstable equilibrium occurs when a body is displaced from its position and topples over rather than returning to its original state. For an object like a ball on a rod, the center of gravity is high and the base of support is extremely small. Any slight displacement causes the center of gravity to lower, creating a net torque in the same direction as the displacement, which prevents the object from returning to its initial position. This is contrasted with stable equilibrium, where displacement raises the center of gravity and the object falls back to its original position, and neutral equilibrium, where the center of gravity remains at the same height during movement.