Question

Which of the following is correct?

(a) The couple moment depends on the axis of rotation

(b) The couple moment depends directly on the radius vector of forces

(c) The couple moment depends only on the distance vector between the forces

(d) The couple moment’s direction is given by the left hand rule

The question was posed to me in an international level competition.

Query is from Moment of a Couple topic in portion Force System Resultants of Engineering Mechanics

Answer 1

Right choice is (c) The couple moment depends only on the distance vector between the forces

Explanation: The couple moment depends only on the distance vector between the forces. The radius vector of the forces are not making the couple depended over it. But the distance vector is driven by subtracting the radius vectors of the forces. This means that the moment of the couple doesn’t directly depend on the radius vector of forces.