Question

What does the moment of the force measure in the calculation of the Mohr circle’s data for the moments of inertia?

(a) The tendency of rotation of the body along with any axis

(b) The moment of inertia of the body about any axis

(c) The couple moment produce by the single force acting on the body

(d) The total work is done on the body by the force

The question was asked in an international level competition.

This interesting question is from Mohr’s Circle for Moments of Inertia topic in section Moments of Inertia of Engineering Mechanics

Answer 1

Correct answer is (a) The tendency of rotation of the body along with any axis

Best explanation: The moment of the force measures the tendency of the rotation of the body along any axis, whether it be the centroid axis of the body, or any of the outside axis. The couple moment is produced by two forces, not by a single force. The total work done is the dot product of force and distance not the cross. A use of Mohr circle can also help in determining the direction.