Explain the difference between static equilibrium and dynamic equilibrium?

Answer 1

A chair has static equilibrium ... a bicycle has dynamic equilibrium.

Dynamic implies movement while staticimplies stationary, but that is a bit misleading. Take an object traveling with a constant velocity in deep space (no air resistance and no gravity). It could be viewed as being as much at rest as an object sitting on a table. The mathematical or chemical use of equilibrium is better. In these cases there is no net change over time even though energy maybe expended. If a steady-state situation in which a reverse process is occurring has a corresponding forward process, at a rate which achieves an exact balance, it is said to be in dynamic equilibrium. With regard to the pressure and volume of water sealed in an exhausted vessel at a constant temperature, a balanced state of constant change is possible in which molecules are constantly being exchanged between ice, water, and water vapour phases. By definition this balanced state of constant change is dynamic equilibrium. Static equilibrium can refer to a steady-state situation with no dynamic forces acting on its potential energy in either reverse or forward processes. By definition, in a state of staticequilibrium there is balance, but no change, disturbance or movement.