In physics, a center-of-momentum frame (zero-momentum frame, or COM frame) of a system is any inertial frame in which the center of mass of the system is at rest (has zero velocity and hence momentum). Note that the center of momentum of a system is not a location, but rather defines a particular inertial frame (a velocity and a direction). Thus "center of momentum" already means "center-of-momentum frame" and is a short form of this phrase.
A special case of the center-of-momentum frame is the center-of-mass frame: an inertial frame in which the center of mass (which is a physical point) is at the origin at all times. In all COM frames, the center of mass is at rest, but it may not necessarily be at rest at the origin of the coordinate system.
Read more about Center-of-momentum Frame: Two-body Problem
Famous quotes containing the word frame:
“The heroes and discoverers have found true more than was previously believed, only when they were expecting and dreaming of something more than their contemporaries dreamed of, or even themselves discovered, that is, when they were in a frame of mind fitted to behold the truth. Referred to the world’s standard, they are always insane. Even savages have indirectly surmised as much.”
—Henry David Thoreau (1817–1862)