Friction: A packing crate rests on a horizontal surface. It is acted on by three horizontal forces: 600 N to the left, 200 N to the right, and friction. The weight of the crate is 400 N. If the 600-N force is removed, the resultant force acting on the crate is
A) zero.
B) 200 N to the right.
C) 200 N to the left.
D) 400 N to the left.
E) impossible to determine from the information given.

Question

Quizplus · Accepted Answer

With the 600-N force removed, the only horizontal forces acting on the crate are the 200-N force to the right and friction. Since the crate was initially at rest (implied by the question's context), the frictional force must have balanced out the net force of 400 N to the left (600 N left - 200 N right). Removing the 600-N force leaves the 200-N force to the right, which would now be balanced by the frictional force acting to the left, resulting in no net force on the crate (zero resultant force).

Friction: a Packing Crate Rests on a Horizontal Surface