Question

A woman pushes a refrigerator across the floor at a steady speed of 20cm/s . If she has to push with a horizontal force of 400 N to keep it moving , is the force of friction less than 400 N , 400 N, more than 400 N, why

Answer 1

For zero acceleration, the net force must be zero. What does that tell you about the friction force?

Answer 2

The force of friction is zero?

Answer 3

constant velocity means NET force of zero.
That means the push exactly balances friction
so friction force is -400 if F is +400