Center-of-momentum frame

The center of mass system (English: Center -of -mass system, CMS) is a coordinate system in which the center of gravity of the considered physical system at rest at the origin. This property is maintained as long as no external influences act as the focus of a closed system for the sake of conservation of momentum moves with constant velocity ( in the laboratory system ). In the center-of many dynamic processes are symmetrical and therefore easier to describe.

From the definition of the priority system follows directly that in him is the total momentum of the masses involved ( the sum of all momentum vectors ) at any time, both before and after a shock or reaction process, equal to zero:

The coordinates of the center of gravity S in the laboratory is calculated from the coordinates of the involved body

The transformation from one system to the other is in the classical case a Galilean transformation, in the relativistic case, a Lorentz transformation.

In astronomy, the center of mass system of a multi- body problem is called baryzentrisches system.