When is an object considered to be in dynamic equilibrium?

An object is considered to be in dynamic equilibrium when it moves at a constant velocity. This is because dynamic equilibrium involves the balance of forces acting on the object, such that there is no acceleration, which means that the object's velocity does not change over time.

In this state, all the forces acting on the object sum to zero, enabling it to maintain its motion without speeding up, slowing down, or changing direction. Thus, the object's state of motion remains constant, reflecting a balance of forces that results in a net force of zero.

While it might seem intuitive to think an object at rest is in equilibrium, true dynamic equilibrium specifically pertains to objects that are in motion. The concept of dynamic equilibrium crucially emphasizes that equilibrium can extend beyond rest to constant motion, as long as the velocity remains unchanged.