IGCSE›Oxford AQA IGCSE Physics›Mind mapsForces & Their InteractionsOxford AQA IGCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTwo typesNon-contact: gravity, electrostatic, magnetismContact: friction, tension, air resistanceContact forces need objects touchingForces come from an interaction between a pairFrictionForce between surfaces that resists motionCan cause heating of the surfacesAir resistance is friction in airScalars, vectorsScalar: magnitude only, e.g. speed, timeVector: magnitude and directionVectors: displacement, velocity, force, momentumForces are drawn as arrowsForcesand their interactionsNkgN/mWeightWeight is the force of gravity on a massW=mgW = mgW=mgMass stays fixed everywhereWeight changes with field strengthSpringsElastic: returns to original shapeInelastic: does not returnHooke's Law: F=keF = keF=keForce-extension graph: straight line through originStretched spring stores elastic potential energyExam tipsMass is in kg, weight is in NUse extension, not total length, in F=keF = keF=keHooke's Law holds only within the limit of proportionality