Mass Point

the concept, used in mechanics, concerning an object of vanishingly small dimensions that has mass. The position of a mass point in space is defined as the position of a geometric point, which greatly simplifies the solution of problems of mechanics. In practice such a body may be considered a mass point in those cases when it moves progressively or when the distances traversed by the points of a body are very great in comparison with its dimensions. When any mechanical system (in particular, a solid) moves, its center of mass (center of gravity) moves in the same way as a mass point with a mass equal to the mass of the entire system would move under the action of all external forces applied to the system.