Moment of a force , Equilibrium of forces

Moment of a force

Equilibrium of forces

When an object is acted upon by different forces and the object does not move or rotate, the forces acting on the object are said to be in equilibrium. The resultant force on th object is zero

Moment

The moment of a force about a point is defined as the product of the force and the perpendicular distance from the point to the line of action of the forces. see fig 1 above.

Moment about point A =Product of  F  and  L

Moment =FL

The point A is called the fulcrum because this is the point at which the body turns.

If this force is at an angle ɸ  as shown in fig 2

Moment =Fsinɸ .L= FL .Sinɸ

The units of Moment =Newton-meter   Nm

Application of moment

Moment is used to lose or to tight a bolt. A long spanner will lose a bolt with ease than a short spanner and a long spanner will apply more torgue on a bolt than short ones. This is because of the moment which depends on length L.

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