BRAINCAKECircular Motion
Revision notes for Circular Motion in OCR Physics A (H556). 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.
- Uniform Circular MotionIf an object is rotating at a steady rate, it has uniform circular motion.
- Angular Displacement1 radian is the angle subtended by an arc of length r where r is the radius of the circle.
- Angular SpeedThe angular speed ω is defined as the angular displacement per second. ω = 2π/T = 2πf The unit of angular speed is radians per second.
- Centripetal AccelerationThe velocity of an object moving at constant speed in a circle changes continuously because its direction changes.
- Proof - centripetal accelerationConsider an object travelling with uniform circular motion at speed v moving in a sort time-interval δt along the perimeter of a circle radius r.
- Centripetal ForceApplying Newton's second law F = ma to the centripetal acceleration gives F = mv2/r Since v = r ω , the centripetal force F = mω2r.
- On the RoadA car going round a roundabout experiences a force towards the centre of the roundabout.
- The London EyeAt the bottom of the wheel, the weight acts downwards and the support force acts upwards.
- A Spin DryerA sock going round a spin dryer experiences a centripetal force.