| vector quantity v = dr/dt, where r is position vector and t is time|
NOTE 1 The velocity is related to a point described by its position vector. The point may localize a particle, or be attached to any other object such as a body or a wave.
NOTE 2 The velocity depends on the choice of the reference frame. Proper transformation between frames must be used: Galilean for non-relativistic description, Lorentzian for relativistic description.
NOTE 3 The coherent SI unit of velocity is metre per second, m/s.