Principle of Moments:
It states, “If a number of coplanar forces are acting simultaneously on a particle, the algebraic sum of the moments of all the forces about any point is equal to the moment of their resultant force about the same point“.
Moment of Force:
It is the turning effect produced by a force, on the body, on which it acts. The moment of a force is equal to the product of the force and the perpendicular distance of the point, about which the moment is required and the line of action of the force.
M = P x l
P = Force acting on the body
l = Perpendicular distance between the point, about which the moment is required, and the line of action of the force.