Question

What is not the condition for the equilibrium in the beams if considered a section on which the method of sections is applied?

(a) ∑Fx=0

(b) ∑Fy=0

(c) ∑Fz=0

(d) ∑F≠0

I had been asked this question during an online interview.

The above asked question is from Internal Forces Developed in Structural Members topic in division Internal Forces of Engineering Mechanics

Answer 1

Correct answer is (d) ∑F≠0

The explanation: For the equilibrium in beams by considering any of the 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. Thus the conditions for the equilibrium of the beams.