Question

If you are getting to know about the direction of the moment caused by the force applied on the body by using your wrist and curling it in the direction of the rotation then which of the following is not right for bending moment diagram?

(a) The thumb represents the direction of the force

(b) The thumb represents the direction of the moment

(c) The fingers represents the direction of the force

(d) The direction in which you curl your wrist is towards the direction of the distance from point of contact of force to the axis of rotation.

This question was posed to me during an interview.

My doubt stems from Bending Moment Diagram in chapter Internal Forces of Engineering Mechanics

Answer 1

Correct choice is (b) The thumb represents the direction of the moment

To elaborate: The curled hand represents a various thing. The direction of the moment axis is given by the thumb. The direction of the force is given by the fingers. As we place the fingers on the force and curl towards the rotational direction of the body about the axis.