Moment of Force:

Define Moment of Force? Describe moment center and moment arm. Also classify the moment. Sol.: It is turning effect produced by force, on the body, on which it is acting. The moment of force is equal to the product of force and perpendicular distance of the point about which the moment is needed, and the line of action of force.

The force acting on body causes linear displacement, while the moment causes angular displacement.

Figure

If M = Moment

F = Force acting on body, and

L = Perpendicular distance between point about which the moment is needed and the line of action of the force.  Then we can say that M = F.L

The point about which moment is considered is called as Moment Center. And Perpendicular distance of point from line of action of the force is called as moment Arm.

Figure

The moment is of two types: Clockwise moment:

It is moment of a force, whose effect is to turn or rotate the body, in clockwise direction. It takes positive.

Figure

Anticlock wise Moment:

It is moment of force, whose effect is to turn or rotate body, in anticlockwise direction. It take positive.

Figure

In the figure; Moment about Point 1 = F.D2 (is Clock wise) Moment about Point 2 = F.D1 (is Anti Clock wise) Moment about Point 3 = 0

That is if point lie on line of action of force, the moment of force about that point is zero.