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A Level Maths · Mechanics · Year 13

A Level Maths Moments revision

Moments is Year 13 only. It deals with rigid bodies such as rods, planks and ladders that can turn as well as slide, and questions often combine it with friction.

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  • Same content for AQA, Edexcel and OCR
  • Step-by-step mark schemes
  • 48-hour free trial, no card
What you need to know

Moments in Year 12 and Year 13

This topic is A Level only: it is not on the AS exam.

Year 12 (AS content)

None: moments starts in Year 13.

Year 13 (full A Level only)

  • The moment of a force about a point
  • Equilibrium of rigid bodies: resolving and taking moments
  • Uniform and non-uniform rods, including when a rod is about to tilt
  • Problems with friction, such as a ladder against a wall

Worked examplemedium5 marks

A non-uniform rod $AB$ of length $3\text{ m}$ and weight $60\text{ N}$ is suspended horizontally by two vertical strings, one at each end. The tension in the string at $A$ is $25\text{ N}$. Find the distance from $A$ of the centre of mass of the rod.

Mark scheme and worked answer
Total upward force: $T_A + T_B = 60 \Rightarrow T_B = 35\text{ N}$   M1 A1. Take moments about $A$: $T_B \times 3 = 60 \times d$, where $d$ = distance from $A$   M1. So $105 = 60d \Rightarrow d = 1.75\text{ m}$   A1 A1.

Then practise: skills to practise · open moments practice questions.

Where it's examined

Moments on the AQA, Edexcel and OCR papers

Every board examines the same A Level Maths content, set by the Department for Education. Only the paper it appears on and the section numbering differ.

BoardSpecification referenceExamined in
AQA 7357AQA section SPaper 2, Section B
Edexcel 9MA0Edexcel topic Mechanics 9Paper 3, Section B
OCR A H240OCR reference 3.04Paper 3, mechanics section
Practice questions

A Level Maths moments exam-style questions

Three examples from the question bank. Every question comes with a step-by-step mark scheme (M, A and B marks) once you start practising.

Question 1easy2 marks

A force of $12\text{ N}$ acts perpendicular to a rod at a point $0.4\text{ m}$ from the pivot. Find the moment about the pivot.

Mark scheme: in the 48-hour free trial.

Question 2medium5 marks

A uniform beam $AB$ of length $6\text{ m}$ and mass $20\text{ kg}$ rests horizontally on supports at $A$ and $C$, where $C$ is $4\text{ m}$ from $A$. A load of mass $5\text{ kg}$ is placed at $B$. Find the reaction at $C$. Take $g = 9.8\text{ m s}^{-2}$.

Mark scheme: in the 48-hour free trial.

Question 3hard6 marks

A uniform ladder $AB$ of length $6\text{ m}$ and mass $20\text{ kg}$ rests against a smooth vertical wall with its foot on rough horizontal ground. The ladder makes angle $70°$ with the ground. Find (i) the reaction at the wall, and (ii) the minimum coefficient of friction at the ground. Take $g = 9.8\text{ m s}^{-2}$.

Mark scheme: in the 48-hour free trial.

Questions are original and written in the style of Edexcel 9MA0, and cover content that AQA and OCR examine too. They are not past-paper questions.

In the practice engine

Skills you can practise

These skills sit in the Mechanics unit of the UK A Level practice engine. Pick any mix of them, set the difficulty, and check each answer against its mark scheme.

Moments & the turning effectEquilibrium of rigid bodiesNon-uniform rods

Open Mechanics practice

Past papers

Past paper questions on moments

Moments can come up on these papers (from each board's paper structure). We haven't mapped individual questions yet, so open a recent paper and look for it.

BoardRecent papers that can test it
Edexcel 9MA0Paper 3: June 2024, June 2023, June 2022
AQA 7357Paper 2: June 2023, June 2022, November 2021
OCR H240Paper 3: June 2024, June 2023, June 2022

Papers are © the exam boards; each page links to the official question paper and mark scheme. All A Level Maths past papers →

Moments: common questions

Is moments on the AQA, Edexcel and OCR A Level Maths exams?

Yes. Moments is part of the A Level Maths content that every board examines: AQA section S, Edexcel Mechanics 9, OCR 3.04. It is assessed in AQA Paper 2, Section B; Edexcel Paper 3, Section B; OCR A Paper 3, mechanics section.

Is moments Year 12 or Year 13 content?

Moments is A Level only, so it is usually taught in Year 13 and is not on the AS exam.

Where should I take moments about?

Take moments about a point where an unknown force acts, so that force has no moment. This often removes one unknown and makes the algebra much shorter.

More A Level Maths mechanics topics

KinematicsForces and Newton's LawsAll A Level Maths topics

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