Final answer:
The box is in dynamic equilibrium because the pushing force equals the friction force, resulting in no acceleration and a constant speed.
Step-by-step explanation:
The question is asking whether a box that is being pushed with a force of 10 N and weighing 30 N, moving at a constant speed on a rough carpet, is in equilibrium. In physics, an object is said to be in equilibrium when the sum of all forces acting on it is zero, and there is no acceleration. Since the box moves at a constant speed and therefore has no acceleration, the pushing force and the friction force are equal and opposite, confirming that the box is in a state of dynamic equilibrium.