# Turning effect

A force may cause an object to turn about a pivot.

The turning effect of a force is called the moment of the force.

Moments act about a pivot in a clockwise or anticlockwise direction.

The anticlockwise moment acts downward on the left, and the clockwise moment acts downwards on the right

## Calculating the moment of a force

The size of the can be calculated using the equation:

moment of a force = force F x perpendicular distance from the pivot d

moment = F x d

• force F is measured in
• distance d is measured in metres (m)
• moment is measured in newton metres (Nm)

from pivot to force d = 0.50 m.

Force F = 10 N

Moment = Fd

Moment = 10 N x 0.50 m

Moment = 5 Nm

This is a clockwise moment.

The force will rotate the object in a clockwise direction about the pivot.

It is important to remember that the distance d is the perpendicular distance from the pivot to the line of action of the force (see diagram).
Question

A force of 15 N is applied to a door handle, 12 cm from the hinge.

Calculate the moment of the force.

Perpendicular distance from pivot to force d = 12 cm = 0.12 m.

Turning force F = 15 N.

Moment = Fd.

Moment = 15 N x 0.12 m.

Moment = 1.8 Nm.

The moment of the force is 1.8 Nm.

## Question

Question

A force of 40 N is applied to a spanner to turn a nut.

The perpendicular distance is 30 cm.

Calculate the moment of the force.

Perpendicular distance from pivot to force d = 30 cm = 0.30 m.

Turning force F = 40 N.

Moment = Fd.

Moment = 40 N x 0.30 m.

Moment = 12 Nm.

The moment is 12 Nm. This is a clockwise moment.