Question

When we apply the equilibrium equations in the free body diagram of the screw, for two force members to be in equilibrium then _________

(a) They both must not be collinear

(b) They must be of different magnitude

(c) They must be in the same direction

(d) They must be in the opposite direction cancelling each other

I have been asked this question in an online interview.

The query is from Frictional Forces on Screws in section Friction of Engineering Mechanics

Answer 1

Right option is (d) They must be in the opposite direction cancelling each other

Explanation: Simply, for the equilibrium the net force must be zero. That is the forces must be collinear if equilibrium is to be established. And they must be in the opposite directions. They also must be of the same magnitude, cancelling each other.