Moment

Key Stage 3

Meaning

A moment is the turning effect of a force.

About Moments

When a force acts on an object with a pivot it becomes a turning force called a moment.

A moment can be calculated by multiplying a force by the distance from a pivot.

The units of a moment are Newton Metres (Nm).

Moments can be used to make Force Multipliers using a pivot and lever.

The longer the lever, the larger the moment that can be produced.

Using moments an effort can be used to lift a load. If the pivot is closer to the load than the effort then the force of effort can be smaller than the load to lift the object.

Equation

Moment = Force x Perpendicular distance from the pivot.

\(M = F \times d\)

Where:

M = Moment

F = Force

d = Perpendicular distance from the pivot.

Example Calculations

A 20N force of effort is applied at a perpendicular distance of 0.15m from the pivot. Calculate the Moment.	A 20N force of effort is applied at a perpendicular distance of 14cm from the pivot. Calculate the Moment.	A 20N force of effort is applied at a perpendicular distance of 100mm from the pivot. Calculate the Moment.
Force = 20N Perpendicular distance = 0.15m \(M = F \times d\) \(M = 20 \times 0.15\) \(M = 3.0Nm\)	Force = 20N Perpendicular distance = 14cm = 0.14m \(M = F \times d\) \(M = 20 \times 0.14\) \(M = 2.8Nm\)	Force = 20N Perpendicular distance = 100mm = 0.10m \(M = F \times d\) \(M = 20 \times 0.10\) \(M = 2.0Nm\)

Key Stage 4

Meaning

A moment is the turning effect of a force.

About Moments

When a force acts on an object with a pivot it becomes a turning force called a moment.

A moment can be calculated by multiplying a force by the distance from a pivot.

The units of a moment are Newton Metres (Nm).

Moments can be used to make Force Multipliers using a pivot and lever.

The longer the lever, the larger the moment that can be produced.

Using moments an effort can be used to lift a load. If the pivot is closer to the load than the effort then the force of effort can be smaller than the load to lift the object.

Equation

Moment = Force x Perpendicular distance from the pivot.

\(M = F \times d\)

Where:

M = Moment

F = Force

d = Perpendicular distance from the pivot.

Example Calculations

A hammer is used to pull out a nail from a wall. A 30N force of effort is applied at a perpendicular distance of 0.18m from the pivot. While the nail is 0.02m away from the pivot. Calculate the force applied to the nail at this point.	A hammer is used to pull out a nail from a wall. A 30N force of effort is applied at a perpendicular distance of 19cm from the pivot. While the nail is 4cm away from the pivot. Calculate the force applied to the nail at this point.	A hammer is used to pull out a nail from a wall. A 30N force of effort is applied at a perpendicular distance of 200mm from the pivot. While the nail is 60mm away from the pivot. Calculate the force applied to the nail at this point.
A 30N force of effort is applied at a perpendicular distance of 0.18m from the pivot. Calculate the Moment.	A 30N force of effort is applied at a perpendicular distance of 19cm from the pivot. Calculate the Moment.	A 30N force of effort is applied at a perpendicular distance of 200mm from the pivot. Calculate the Moment.
1. State the known quantities Force = 30N Perpendicular distance between effort and pivot = 0.18m Perpendicular distance between effort and pivot = 0.02m	1. State the known quantities Force = 30N Perpendicular distance between effort and pivot = 19cm = 0.19m Perpendicular distance between effort and pivot = 4cm = 0.04m	1. State the known quantities Force = 30N Perpendicular distance between effort and pivot = 200mm = 0.200m Perpendicular distance between effort and pivot = 60mm = 0.06m
2. Find the moment caused by the effort. \(M = F \times d\) \(M = 30 \times 0.18\) \(M = 5.4Nm\)	2. Find the moment caused by the effort. \(M = F \times d\) \(M = 30 \times 0.19\) \(M = 5.7Nm\)	2. Find the moment caused by the effort. \(M = F \times d\) \(M = 30 \times 0.20\) \(M = 6.0Nm\)
3. Calculate the Force applied to the nail from the moment. Moment = 5.4Nm Perpendicular distance = 0.02m \(M = F \times d\) \(5.4 = F \times 0.02\) \(F = \frac{5.4}{0.02}\) \(F = 270N\)	3. Calculate the Force applied to the nail from the moment. Moment = 5.7Nm Perpendicular distance = 4cm = 0.04m \(M = F \times d\) \(5.7 = F \times 0.04\) \(F = \frac{5.7}{0.04}\) \(F = 142.5N\)	3. Calculate the Force applied to the nail from the moment. Moment = 6.0Nm Perpendicular distance = 60mm = 0.06m \(M = F \times d\) \(6.0 = F \times 0.06\) \(F = \frac{6.0}{0.06}\) \(F = 100N\)

References

AQA

Moment, pages 168-9, GCSE Physics; Student Book, Collins, AQA

Moments, page 57, GCSE Physics; The Revision Guide, CGP, AQA

Moments, pages 120-123, 126-127, GCSE Physics; Third Edition, Oxford University Press, AQA

Moments, pages 165, 166, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA

Edexcel

Moments, page 136, GCSE Physics, Pearson Edexcel

Moments, page 68, GCSE Physics; The Revision Guide, CGP, Edexcel

Moments, pages 211-213, GCSE Physics, CGP, Edexcel

OCR

Moment (turning effect), pages 84-85, Gateway GCSE Physics, Oxford, OCR

Moments, pages 38, 39, Gateway GCSE Physics; The Revision Guide, CGP, OCR