Question

For determination of the equilibrium state in the free body diagram the basic way of getting the direction of the moment caused by the force is:

(a) The use of left hand rule with thumb giving the direction of the moment

(b) The use of right hand rule with thumb giving the direction of the moment

(c) The use of right hand rule with forefinger giving the direction of the moment

(d) The use of left hand rule with forefinger giving the direction of the moment

I got this question by my school principal while I was bunking the class.

My question is from Characteristics of Dry Friction topic in division Friction of Engineering Mechanics

Answer 1

Right option is (b) The use of right hand rule with thumb giving the direction of the moment

Easy explanation: The basic way of doing so is to use right hand rule and not the left hand rule. 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.