IGCSE›Edexcel IGCSE Physics›Mind mapsForces, Movement & Changing ShapeEdexcel IGCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsResultant forceForce can change speed, shape or directionForce is a vector; scalars have size onlySame direction: add; opposite: subtractFriction always opposes motion2000 N forward, 500 N back gives 1500 NForce equationsF=m×aF = m \times aF=m×aW=m×gW = m \times gW=m×gMass is constant; weight depends on gggStopping distanceThinking + braking distanceHigher speed increases bothWet or icy roads increase braking distanceTiredness or alcohol increase thinking distanceForcesand changing shapeNkgN/kgTerminal velocityWeight greater than air resistance at firstDrag grows with speed, resultant shrinksDrag equals weight: zero resultant forceThen falls at constant maximum speedSpringsHooke's law: extension proportional to forceCurve starts at the limit of proportionalityElastic: returns to original shapePast elastic limit: permanent deformationExam tipsHooke's law applies to the straight region onlyNever mix up mass (kg) and weight (N)