ForcesAQA GCSE Physics (8463)

Moments, Levers and Gears

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

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Master the topic

Worked examples2 Key formulae1 Definitions3 Common mistakes2

Step-by-step worked examples

01.Moment of a spanner
Foundation
Question
A mechanic applies a 120 N force at the end of a spanner 0.30 m long. Calculate the moment.
Solution
1. 1
  Apply formula.
  $M = F \times d = 120 \times 0.30 = 36\,\text{N·m}$
Answer
36 N·m.
02.Balance the see-saw
Higher
Question
A 200 N child sits 1.5 m left of a see-saw pivot. Where must a 300 N adult sit (right of pivot) to balance?
Solution
1. 1
  Equilibrium.
  $F_1 d_1 = F_2 d_2$
2. 2
  Substitute.
  $200 \times 1.5 = 300 \times d$
3. 3
  Solve.
  $d = 300/300 = 1.0\,\text{m}$
Answer
1.0 m right of the pivot.

Key formulae

Moment
$M = F \times d$
- $M$
  — Moment (N·m)
- $F$
  — Force (N)
- $d$
  — Perpendicular distance from pivot to line of force (m)
When to use
Whenever calculating turning effect. Recall (not on equation sheet).

Practice with flashcards

Card 1 of 30 known · 0 to review

Key definitions and keywords

MomentExaminer keyword: The turning effect of a force about a pivot. M = F × d.
Principle of momentsExaminer keyword: For an object in rotational equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments about any point.
Lever: A rigid bar pivoted at a fulcrum, used to multiply force at the cost of distance moved.

Common mistakes and misconceptions

Mistake
Using diagonal distance instead of perpendicular.
Why it happens
Confusion with lever length.
How to avoid it
Perpendicular distance = shortest distance from pivot to line of force.
Mistake
Writing 'J' for moments.
Why it happens
J = N·m dimensionally but used for energy.
How to avoid it
Use N·m for moments (or N m).

ForcesAQA GCSE Physics (8463)

Moments, Levers and Gears

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

Previous Next

Master the topic

Worked examples2 Key formulae1 Definitions3 Common mistakes2

Step-by-step worked examples

01.Moment of a spanner
Foundation
Question
A mechanic applies a 120 N force at the end of a spanner 0.30 m long. Calculate the moment.
Solution
1. 1
  Apply formula.
  $M = F \times d = 120 \times 0.30 = 36\,\text{N·m}$
Answer
36 N·m.
02.Balance the see-saw
Higher
Question
A 200 N child sits 1.5 m left of a see-saw pivot. Where must a 300 N adult sit (right of pivot) to balance?
Solution
1. 1
  Equilibrium.
  $F_1 d_1 = F_2 d_2$
2. 2
  Substitute.
  $200 \times 1.5 = 300 \times d$
3. 3
  Solve.
  $d = 300/300 = 1.0\,\text{m}$
Answer
1.0 m right of the pivot.

Key formulae

Moment
$M = F \times d$
- $M$
  — Moment (N·m)
- $F$
  — Force (N)
- $d$
  — Perpendicular distance from pivot to line of force (m)
When to use
Whenever calculating turning effect. Recall (not on equation sheet).

Practice with flashcards

Card 1 of 30 known · 0 to review

Key definitions and keywords

MomentExaminer keyword: The turning effect of a force about a pivot. M = F × d.
Principle of momentsExaminer keyword: For an object in rotational equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments about any point.
Lever: A rigid bar pivoted at a fulcrum, used to multiply force at the cost of distance moved.

Common mistakes and misconceptions

Mistake
Using diagonal distance instead of perpendicular.
Why it happens
Confusion with lever length.
How to avoid it
Perpendicular distance = shortest distance from pivot to line of force.
Mistake
Writing 'J' for moments.
Why it happens
J = N·m dimensionally but used for energy.
How to avoid it
Use N·m for moments (or N m).

Moments, Levers and Gears

Master the topic

Step-by-step worked examples

01.Moment of a spanner

02.Balance the see-saw

Key formulae

Practice with flashcards

Key definitions and keywords

Common mistakes and misconceptions

Moments, Levers and Gears

Master the topic

Step-by-step worked examples

01.Moment of a spanner

02.Balance the see-saw

Key formulae

Practice with flashcards

Key definitions and keywords

Common mistakes and misconceptions