Turning effects of forces

Moments, rotational equilibrium, the principle of moments and centre of gravity.

Learning goals

Describe a moment as a force's turning effect in everyday examples
Apply moment = force × perpendicular distance from the pivot
State the principle of moments for a body in equilibrium
apply the principle of moments to new situations or to solve related problems
show an understanding that the weight of a body may be taken as acting at a single point known as its centre of gravity

G3 Science (Physics) · Topic 5

Begin with the complete topic lesson. Then try a short check, use the feedback to review one idea and come back later for another attempt.

Moments, rotational equilibrium, the principle of moments and centre of gravity.

Check the required topic capabilities and get focused practice for ideas that need another look.

A moment describes the clockwise or anticlockwise turning effect of a force about a chosen pivot.
Use moment = force × perpendicular distance from the pivot to the force's line of action.
For equilibrium, total clockwise moment equals total anticlockwise moment about the same pivot.
Include every relevant force, including a beam's own weight unless it is stated to be negligible.
Treat the whole weight of a body as acting through its centre of gravity.

Turning effects of forces is Topic 5 in K326 / K327 Physics component · 2027.

The lesson and questions stay at the depth required for this course.

Reviewed 9 Aug 2026

Course and syllabus information