Question

If the resolved force or the force which you get as the answer after solving the question is negative for the equilibrium of the potential energy, then what does this implies?

(a) The force is in the reverse direction w.r.t the direction set in the free body diagram

(b) The force is not in the reverse direction w.r.t the direction set in the free body diagram

(c) The force component is not possible

(d) The force is possible, but in the direction perpendicular to the resultant force

The question was posed to me during an online interview.

My query is from Potential Energy Criterion for Equilibrium topic in portion Principle of Virtual Work of Engineering Mechanics

Answer 1

Right choice is (a) The force is in the reverse direction w.r.t the direction set in the free body diagram

The explanation is: The negative sign implies things in the opposite manner. If the force is coming negative this doesn’t mean that it is impossible. But it means that the force is in the opposite direction w.r.t the direction set by you in the free body diagram.