Momentum
in mechanics, the force possessed by matter in motion; the product of the mass by the velocity of a body. Thus a ball of four pounds' weight moving uniformly at the rate of 18 feet in a second would have double the momentum that one of three pounds' weight moving at the rate of 12 feet per second would possess, for 4X18 is 72, and 3×12=36, or half as much. The force of percussion, that is, the force with which a moving body strikes an object, is the same in amount as the momentum of the former.