Sentrumavmassenrammen

Sentrumavmassenrammen is a term that can be understood as the center-of-mass frame of a system of particles. In practice it refers to the inertial reference frame in which the total momentum of the system is zero. The phrase is not a standardized Norwegian technical term, and in many sources the more common expressions center-of-mass frame, centre-of-mass system, or CMS are used; however, the compound form may appear in some translations or specialized texts.

In the center-of-mass frame, the motion of the system is described relative to the collective mass distribution rather than any single particle. The velocity of the center-of-mass frame is given by the total momentum divided by the total mass (in non-relativistic settings), and in this frame the sum of the momenta of all constituents vanishes. For a two-particle system, the two particles have equal and opposite momenta in the CM frame, and the kinetic energy available to their relative motion is minimized with respect to the total energy in the lab frame. In relativistic contexts, the CM frame is defined by the vanishing of the total spatial part of the four-momentum, and the invariant mass of the system is taken as the total energy in that frame.

Applications of the center-of-mass frame include simplifying collision and decay problems in particle and nuclear physics, where analyses often separate overall motion from relative motion. It is also a standard reference in experimental design and data interpretation, providing a symmetric basis for energy and momentum distributions. While the exact term sentrumavmassenrammen may be uncommon, the underlying concept is widely used under the more standard designations mentioned above.