Final answer:
A box moving at a steady speed is an example of dynamic equilibrium. Here, all forces are balanced, and there is no net acceleration, though the box continues to move at a constant velocity. Static equilibrium would apply if the box were not moving at all.
Step-by-step explanation:
Dynamic or Static Equilibrium
When a box is moving at a steady speed, meaning its speed is not increasing or decreasing, this is an example of dynamic equilibrium. In dynamic equilibrium, the object is in motion, and all forces acting upon the object are balanced. Despite the continuous movement, there is no acceleration because the net force is zero.
In contrast, static equilibrium occurs when an object is at rest, and there is no net movement or force acting on it. Both types of equilibrium indicate that the forces are balanced; the primary difference is that dynamic equilibrium involves constant velocity motion, while static equilibrium involves no motion.
An example of dynamic equilibrium could be a car moving at a constant velocity on a straight, level road where the frictional force and air resistance balance the forward thrust of the car's engine.