Angular motion

• Angular motion is the movement of a body or part of a body in a circular path about an axis of rotation.
• Eccentric force is a force applied outside the centre of mass, resulting in angular motion.
• Torque is a measure of the turning (rotational or eccentric) force applied to a body
• If an eccentric force is applied to a body , it will rotate around one or more of the three axes of rotation.
• Axes of rotation

  • Longitudinal - runs from top to bottom of eg ( trampolinist performs a full twist)
  • Transverse - Runs from side to side - eg ( A front somersault )
  • Frontal - Runs from front to back - eg (Gymnast performs a cartwheel)
• Descriptions of angular motion

  • Moment of inertia (MI)
  • Angular velocity
  • Angular momentum
• $MI\ =$$\ \sum_{ }^{ }m\ x\ r^2$
• moment of inertia = mass x distribution of mass from the axis of rotation2
• Angular velocity is the rate of change in angular displacement or rate of rotation. units (radians per second ) rad/s
• Angular velocity = angular displacement / time taken
• Angular momentum

  The quantity of angular motion possessed by a body. units (kilogram metres2 per second) kgm2/s
• Moment of inertia 


  The resistance of a body to change its angular motion or rotation. units (kilogram metres2) $kgm^2$
• Angular momentum = moment of inertia x angular velocity