Answer: When the box is on a step and in a resting position then in this situation, the forces acting on the box is said to be balanced forces. While carrying the box to the top of the stair then the forces acting on it will be unbalanced forces.
Step-by-step explanation:
When the box is on a step and in a resting position then the forces acting on the box are acting in an equal in magnitude and opposite in direction. Therefore, these forces are balanced forces.
While carrying the box to the top of the stair then the forces acting on it will be unbalanced forces because the box is changing its state. There is an unbalanced force which opposes the motion of the box.