Question

a horizontal force of 300 N is needed to push a crate along the floor at constant speed. What is the friction force on the crate?

Answer 1

Since a 100-N force is being used to push the crate in one direction, and there is a total net force of 0, the force of friction acting on the crate must also be 100 N. This frictional force points in the direction opposite of the push.