Question

What is not the condition for the equilibrium in three dimensional system of axis for the composite bodies if we are determining the moment of inertia for them?

(a) ∑Fx=0

(b) ∑Fy=0

(c) ∑Fz=0

(d) ∑F≠0

I had been asked this question in semester exam.

I'm obligated to ask this question of Moment of Inertia for Composite Areas in portion Moments of Inertia of Engineering Mechanics

Answer 1

Correct answer is (d) ∑F≠0

The best I can explain: For the equilibrium in the three dimensional system of axis we have all the conditions true as, ∑Fx=0, ∑Fy=0 and ∑Fz=0. Also, we have the summation of the forces equal to zero. Which is not a non-zero value.