Question

What does FLsinθ means/ represent for the moment (M) of the force (F) acting on the body at a distance L from the axis of the rotation?

(a) The direction vector of the moment

(b) Unit vector of the moment vector

(c) The magnitude of the moment caused by the force on the body

(d) The perpendicular distance of the force from the axis of rotation

The question was asked by my school teacher while I was bunking the class.

The query is from Moment of a Force topic in division Force System Resultants of Engineering Mechanics

Answer 1

Right answer is (c) The magnitude of the moment caused by the force on the body

Explanation: The moment of the force about the axis of rotation by the application of the force on the body is given by the cross product of both. If the force not perpendicular to the axis, and making angle θ then cosine form of angle is used. Thus, FLsinθ represents the magnitude of the moment.