Chapter 4 · 4.2 Moments · Session 3
Moments & the Principle of Moments
Learn how a force produces a turning effect about a pivot, define the moment of a force, and apply the principle of moments to solve balance problems — the foundation for levers, beams and equilibrium.
You'll learn to
- ✓ Define moment = force × perpendicular distance
- ✓ State & apply the principle of moments
- ✓ Solve for unknown forces on a balanced beam
Ask Mr & Mrs Choolun about this session
Common questions for this session
Does the pivot always have to be at the centre?
No — the pivot can be anywhere. Take moments about whichever point removes an unknown force; the principle still holds: clockwise = anticlockwise moments.
Mr Choolun · Teacher
What units is a moment measured in?
Newton-metres (N·m) — force in newtons × distance in metres.
Will this be in Paper 2?
Yes — moments are a frequent structured-question topic. See the attached worked examples.
Your questions are private to your teacher. Helpful answers may be added here for everyone.
Moments — summary notes.pdf
3 pages · 480 KB · view-only
Worked examples — balanced beams.pdf
5 pages · 1.2 MB · view-only
📁 Documents are view-only (watermarked) to protect content.
My notes
Transcript
0:42So a moment is the turning effect of a force about a pivot…
7:18…multiply the force by the perpendicular distance to the line of action.
9:05For a balanced beam, total clockwise moments equal total anticlockwise moments.