A horizontal force of 100 N is required to push a box across the floor at a constant velocity.

Question

a) Show that the net force acting on the box is zero.

b) Show that the friction force that acts on the box is 100 N.

Answer 1

a. Fap-Ff = m*a = m*0
Fap - Ff = 0
The velocity is constant. Therefore,
the acceleration is zero.
Fap = Force applied.
Ff = Force of friction.

b. Fap - Ff = 0
100 - Ff = 0
Ff = 100 N.