Moments and their application

MOMENTS OF A FORCE:
It is the turning effect produced by a force,on the body,on which it acts,The moments of a force is equal ton 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.

Mathematically,moment,
M=p x l
where p=force acting on the body,and
        l=perpendicular distance between the point,about which the moment is required and the line of                action of the tree.

UNITS OF MOMENTS: since the moment of a force is the product of force and distance,therefore the units of the moments will depend upon the units of force and distance.Thus ,if force is in Newton and the distance is in maters,then the units of moments will be Newton-meter (briefly written as N-m).similarly, the units of moments may be kN-m(i.e.kN x m ),N-mm (i.e. N x mm) etc.
TYPE OF MOMENTS
Broadly speaking,the moments are of the following two types:
1.Clockwise
2.Anticlockwise moments.

CLOCKWISE MOMENT:
It is moment of a force,whose effect is to turn or rotate the body,about the point in the same direction in which hands of  a clock move .

ANTICLOCKWISE MOMENT:
it is the moment of a force,whose effect is to turn or rotate the body,about the point in the opposite direction in which the hand of a clock move.

NOTE:
The general convention is to take clockwise moments as positive and anticlockwise  moment as negative.

VARIGNON'S PRINCIPLE OF MOMENTS (OR LAW OF MOMENTS)
It states, "If a number of coplanar forces are acting simultaneously on a particle,the algebraic sum of the moments of the forces about any point is equal to the moments of their resultant force about the same point

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