anchor: Body:getLinearDamping
  Gets the linear damping of the Body.
  
  The linear damping is the ''rate of decrease of the linear velocity over time''. A moving body with no damping and no external forces will continue moving indefinitely, as is the case in space. A moving body with damping will gradually stop moving.
  
  Damping is not the same as friction - they can be modelled together.
  damping = Body:getLinearDamping()
  damping number The value of the linear damping.