Question

a horizontal force of 100N is required to push a crate across a factory floor at a constant speed. What is the net force acting on the crate/ What is the force of friction acting on the crate?

Answer 1

If the crate is moving along the floor in the same direction with a constant speed, it is in dynamic equilibrium. Equilibrium means there is no net force acting on the crate.

Since there is no net force on the crate, there must be a friction force on the crate equal in magnitude and opposite in direction to the applied horizontal force. Therefore the force of friction acting on the crate is 100N.