BRAINCAKEThe Principle of Moments
The principle of moments states that for a body in (rotational) equilibrium, the sum of clockwise moments about any point is equal to the sum of anticlockwise moments about the same point.
For example, a wooden beam 150cm long with a weight of 20N rests on a support at one end and is fixed to a vertical string at the other end.
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Key terms in this lesson
- Equilibrium
- An object is in equilibrium when the resultant force and the resultant moment acting on it are both zero.
- Moment
- The turning effect of a force about a pivot, equal to the force multiplied by the perpendicular distance from the pivot to the line of action of the force.
More in Forces in Equilibrium
- Adding Two Perpendicular Vectors
- Equilibrium
- Three Forces in Equilibrium
- Moments
- Centre of Mass
- Couples
- Stable Equilibrium
- Tilting and Toppling
All 20 lessons in Forces in Equilibrium · All AQA AS-level Physics topics