Circular Measure
- Angle, θ, in radians = Arc length / Radius
- 1 radian = 360 degrees / 2π
- Z(degrees) = Z x ( π / 180 ) (radians)

Angular Displacement
- Angle an object turns through with respect to a fixed point

Angular Velocity
- Instantaneous angular velocity, ω = dθ / dt

- Average angular velocity ,<ω> = Δθ / Δt



- If object has constant angular velocity, ω = <ω>

Relationship between tangential speed and angular velocity

- v = rω

Period and Frequency
Period
- Time taken for an object in circular motion to make one complete revolution
Frequency
- Number of revolutions or cycles made per unit time



- ω = 2π / T = 2πf

Uniform Circular Motion
- Motion of an object travelling at constant speed in a circular path
- Magnitude of the velocity is constant but direction is always changing
- With a change in velocity, there is an acceleration

- Centripetal Acceleration is directed radially inwards towards the centre
- a = v^2 / r
- a = rω^2

- a = vω

- To provide the acceleration, there must be a force
- F = ma
- F = m v^2 / r
- F = m rω^2
- F = m vω