Question

Which of the following is correct for a screw being rotated?

(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

I got this question in quiz.

This is a very interesting question from Frictional Forces on Screws in section Friction of Engineering Mechanics

Answer 1

Correct option 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 moment of the couple doesn’t directly depend on the radius vector of forces.