There are three types of equilibrium: stable, unstable and neutral. Equilibrium is a state of balance. An object is in a state of equilibrium when the forces acting on it are equal from both sides.
Equilibrium can be used by analysts to describe the state of the economy. More often, however, the different types are used in reference to objects or matter.
- Stable equilibrium This type of equilibrium occurs when the object returns to its original position after being disturbed. This happens because the object's center of gravity is below the point at which it is suspended or supported. An example is a book laying flat on a table.
- Unstable equilibrium When the object's center of gravity is above the point at which it is supported or suspended, it has unstable equilibrium. In this case, the object never returns to its original position but rather continually moves to new positions. An example would be a ball on top of a spherical object.
- Neutral equilibrium When forces move an object slightly, and then it stops moving, that is neutral equilibrium. The center of gravity lies directly at the point of support or suspension. An example of this is rolling a ball slightly so it stops soon after the movement begins.