Moments
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Moments

The turning effect on the bolt by the spanner is called a "moment" or torque.

Moments and torque

The moment = the size of the force (N) multiplied by the length of the lever (m)

Moment = Force x Distance

Moments are measured in Nm

therefore: moment (Nm) = force (N) x distance (m)

Principle of Moments

An object is in equilibrium, i.e. it is balanced and not turning or moving when:

The sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the point.

 
Moments
 

The see-saw is balanced because the clockwise moment is equal to the sum of the anticlockwise moments, i.e.

Moment = Force x Distance

Moment at A = 50N x 2m = 100 Nm anticlockwise moment

Moment at B = 50N x 1m = 50 Nm anticlockwise moment

Anticlockwise moment at A + B = 150 Nm

Moment at C = 150N x 1m = 150 Nm clockwise moment

The see-saw is balanced because the clockwise moment is equal to the sum of the anticlockwise moments.

Bending moment

 
 
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