anchor: Body:getAngularVelocity
  Get the angular velocity of the Body.
  
  The angular velocity is the ''rate of change of angle over time''.
  
  It is changed in World:update by applying torques, off centre forces/impulses, and angular damping. It can be set directly with Body:setAngularVelocity.
  
  If you need the ''rate of change of position over time'', use Body:getLinearVelocity.
  w = Body:getAngularVelocity()
  w number The angular velocity in radians/second.