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Moments

Moments are a measure of the turning effect of a force around a specified turning point or pivot.

Picture of a hammer removing a nail. The diagram shows the movement of the hammer, force and the distance.

A moment is a force times a distance. The unit used to measure a moment is newton metres (Nm).

Picture of a pivot point with a steel bar attached to it. There is a moment arrow pointing upwards and a force arrow equal to 10 N pointing downwards.

M = F x d

M = 10 N x 5 m

M = 50 Nm

Note that the units are Nm (newton metres) not N/m (newtons per metre).


Need more information about units of force?


Picture of steel bar at the original position and a dotted line bar showing the position due to the force and resulting action.

The direction of a moment is opposite to the direction of the force.


Picture of a clock showing the positive moments as clockwise and the negative moments as anti-clockwise.

The convention is that:

  • clockwise moments are positive
  • anti-clockwise moments are negative.
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