BRAINCAKEMoments and Equilibrium
An object in equilibrium has no net force acting on it and no net moment (rotational equilibrium).
The moment of a force is its turning effect. It is defined as the force × perpendicular distance of the line of action of the force from the pivot.
moment = F x cos θ
The perpendicular distance of the line of action of the force from the pivot P is xcosθ
Alternatively the force F could be resolved parallel and perpendicular to the line through the pivot P.
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Key terms in this lesson
- weight
- The gravitational force acting on an object's mass.
- tension
- The force within a stretched object, such as a rope or cable, that opposes the stretching.
More in Forces and Motion
- Weight, Mass, Accleration
- Centre of Mass
- Free-Body Force Diagrams
- Drag and Terminal Velocity
- Couples and Torques
- Forces in Equilibrium
- Density and Pressure
- Pressure in Fluids and Archimedes Principle
All 17 lessons in Forces and Motion · All OCR AS-level Physics topics