What is the difference between static and dynamic equilibrium?

Static equilibrium is when forces are balanced and there's no movement, while dynamic equilibrium involves balanced forces but with ongoing movement.

In more detail, static equilibrium refers to a state where all forces acting upon an object are balanced, resulting in no change in motion. This means that the object is either at rest or its centre of mass moves at a constant velocity. For example, a book lying on a table is in static equilibrium because the forces acting on it (gravity pulling it down and the table pushing it up) are equal and opposite, so there's no net force and the book doesn't move.

On the other hand, dynamic equilibrium is a state of balance between continuing processes. In this case, the forces are also balanced, but the object is in motion. However, this motion is constant - the object moves at a steady speed in a straight line. This is because the forces acting on it, while balanced, are doing so in a way that allows for constant motion. An example of dynamic equilibrium is a car moving at a constant speed. The forces of friction and air resistance are balanced with the force of the car's engine, resulting in a steady speed.

In the context of chemistry, dynamic equilibrium refers to a state in a chemical reaction where the rate of the forward reaction equals the rate of the reverse reaction. This means that the concentrations of the reactants and products remain constant over time, even though the reactions are still happening. This is different from static equilibrium, where there would be no ongoing reaction because the reactants and products are in a stable state.