* Net force is zero. Since the box moves with constant velocity, it means there is no acceleration. Newton's First Law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Therefore, the net force acting on the box must be zero.

* There are multiple forces acting on the box. Here's a breakdown:

* Applied force: The man pushing the box.

* Friction force: The resistance of the rough wooden floor against the box's motion.

* Gravitational force: The force pulling the box downwards (weight).

* Normal force: The force exerted by the floor, pushing upwards on the box, counteracting its weight.

* The forces are balanced. Since the net force is zero, the forces acting on the box must be balanced. The applied force from the man pushing is equal and opposite to the friction force. Additionally, the normal force is equal and opposite to the gravitational force.

In summary: For the box to move at a constant velocity, the forces acting on it must be balanced. The man's push is countered by friction, and the box's weight is balanced by the normal force from the floor.