Circular Motion

Circular Motion

1. The Radian

   • Angles are measured in radians. One radian is the angle at the centre of a circle subtended by an arc, which is equal in length to the radius of the circle
   • θ = s÷r
     • θ = angle
     • s = arc length
     • r = radius
   • θ = ωt
     • θ = angle
     • ω = angular velocity
     • t = time

2. Circular motion

3. Centripetal force

   • If a body is moving in a circle the force towards the centre needed to keep it moving in that circle is called Centripetal Force.
   • Used when we have velocity
   • Used when we have angular velocity
   • If a body is moving in a circle the acceleration it has towards the centre of that circle is called Centripetal Acceleration

4. Deriving formulae

   • To derive: v = rω
     • Relationship between linear speed and angular velocity
   • To derive:
     • Relationship between periodic time and radius of a satellite in orbit

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