Question

select the correct answer.
in the diagram, a force of 20 newtons is applied to a block. the block is in dynamic equilibrium. what is the magnitude and direction of the frictional force?

push of 20 newtons

a. 20 newtons in the direction of the applied force
b. 20 newtons opposite to the direction of the applied force
c. 20 newtons perpendicular to the direction of the applied force
d. 20 newtons in two directions, perpendicular and in the direction of the applied force
e. no friction is acting on the block.

Explanation:

Dynamic equilibrium means the net force on the block is zero. The applied force is 20 N to the right. Frictional force opposes motion, so it must balance the applied force. Thus, friction has magnitude 20 N and direction opposite to the applied force.

Answer:

B. 20 newtons opposite to the direction of the applied force