The unit of momentum is kg m/s or newton seconds (Ns) . Momentum is defined as the product of mass and velocity, and it is a vector quantity that has both magnitude and direction. The equation for momentum is p = mv, where p is momentum, m is mass, and v is velocity. The SI unit of momentum is kg m/s, which is equivalent to Ns. In the CGS system, the unit of momentum is g cm/s. Other units of momentum include kg mi/hr and kg km/hr.