• Any object travelling in a uniform circular motion at the same speed travels with a?constantly changing velocity
• This is because it is?constantly changing direction, and is therefore accelerating
• The angular speed (?) of a body in circular motion is defined as:

The rate of change in angular displacement with respect to time

• Angular speed is a scalar quantity, and is measured in rad s^-1

When an object is in uniform circular motion, velocity constantly changes direction, but the speed stays the same

• Taking the angular displacement of a complete cycle as 2π, the angular speed ? can be calculated using the equation:

• Where:
  • Δθ =?change in?angular displacement?(radians?)
  • Δt =?time interval (s)
  • T =?the?time period?(s)
  • f?=?frequency?(Hz)
• Angular velocity is the same as angular speed, but it is a vector quantity
• When an object travels at constant linear speed?v?in a circle of radius?r, the angular velocity is equal to:

• Where:
  • v?is the?linear?speed (m s^-1)
  • r?is the radius of orbit (m)
• This equation tells us:
  • The greater the rotation angle θ in a given amount of time, the greater the angular velocity ?
  • An object rotating further from the centre of the circle (larger r) moves with a smaller angular velocity (smaller ?)