Lesson 6 of 8

Turning forces

Goal: Calculate the moment of a force.

Puzzles for this lesson

A force can make something turn about a pivot. The turning effect of a force is called its moment.

Moment = force × distance from the pivot. Force in newtons (N). Distance in metres (m). Moment in newton metres (N m).
Push further from the pivot and the same force gives a bigger moment. That is why a long spanner shifts a tight nut.
A moment turns one way: clockwise or anticlockwise.
A lever is a rigid bar that turns about a pivot. Spanners, door handles, scissors and see-saws are all levers.

Your turn

This lesson’s activity starts here in a moment.

I can use moment = force × distance from the pivot.I can give the unit.

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Moment The turning effect of a force

Pivot The point that a lever turns about

Newton metre The unit of a moment (N m)

Lever A rigid bar that turns about a pivot

For teachers: AQA 3.1.3 Extend in part · Pearson Edexcel 42.1, 42.2 · Cambridge 8Pf.04