# A Level PE - Angular Motion

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• Created by: hotzmc
• Created on: 31-12-17 01:24

A Level PE - Angular Motion:

Angular Motion:

Angular Motion: Movement of a body or a body part in a circular path about an axis of rotation

• E.g. a gymnasts whole body will rotate around the bar (axis of rotation), an athletes legs will rotate around the hip joint as the run
• Angular motion results from an eccentric force being applied to a body where the force is applied outside the centre of a body’s mass
• An eccentric force is also known as a torque - a turning or rotational force

Angular Motion Descriptors:

• Angular displacement
• Angular velocity
• Angular momentum
• Angular acceleration

Angular Displacement:

Angular Displacement: The angle through which an object moves on a circular path

• It is measured in units of radians
• 1 radian (r) = 57.3o
• Angle = Arc length/radius or arc = l/r

Angular Velocity:

Angular Velocity: The rate of change in angular displacement

• Measured in radians per second (rate of spin)
• Angular velocity = angular displacement /time taken
• E.g. A trampolinist performing a seat drop rotated their legs clockwise about the axis 1.57 radians in 0.5 seconds. The average angular velocity is 3.14 rad/s (1.57 rad/0.5s)

Angular Momentum:

Angular Momentum: The quantity of angular motion possessed by a body

• It is the rotational equivalent of momentum
• Angular momentum = moment of inertia x angular velocity
• It’s measured in kilograms metres squared radians per second (Kgm2