BRAINCAKEForces in Equilibrium
Revision notes for Forces in Equilibrium in AQA Physics (7407). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Vector and Scalar QuatitiesPhysics is about physical quantities.
- Vector QuantitiesVectors can be represented by arrows.
- Adding Vectors - Scale DiagramVectors can be added by using a scale diagram.
- Resolving VectorsAll vectors can be split into two components perpendicular to each other.
- Adding Two Perpendicular VectorsParallel and anti-parallel vectors are simply added together as they are in one dimension.
- EquilibriumWhen an object is in equilibrium, all the forces acting on the object are balanced.
- Three Forces in EquilibriumAt equilibrium: Note: the horizontal components are equal.
- MomentsAn object in equilibrium has no net force acting on it and no net moment (rotational equilibrium).
- The Principle of MomentsThe 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…
- Centre of MassAn object's gravitational force (its weight) acts through a point called its centre of gravity.
- CouplesA couple is a pair of equal and opposite forces acting on a body along parallel lines.
- Stable EquilibriumStable Equilibrium When an object is displaced, it returns to its equilibrium position when released.
- Tilting and TopplingUnstable Equilibrium If an object is tilted, the object will topple if the displaced centre of mass is no longer above or below the point of support…
- TiltingAn object at rest on a surface is acted on by a force that turns it clockwise or anticlockwise about a point.
- TopplingA tilted object will topple if the line of action of its weight passes beyond the pivot A inifotm block will topple if the tan of its angle of tilt…
- Objects On a SlopeWhen a vehicle is on a slope if the line of action of the weight lies outside the wheel base the vehicle will topple.
- Free Body Force DiagramsA free-body force diagram isolates all the forces acting on an object.
- Triangle of ForcesAt equilibrium there is no resultant force and no resultant moment.
- Condition for EquilibriumAt equilibrium there is no resultant force and no resultant moment.
- How to Lift a WeightLet W be the weight of the upper part of the body, T be the tension in the back muscles, W0 is the weight to be lifted and R is the reaction force…