momentum

The product of mass and velocity — a conserved vector quantity describing motion.

• conservation of momentum: total momentum in a closed system is constant
• Newton’s second law restated: force is the rate of change of momentum
• central to mechanics, collisions, and orbital dynamics
• relativistic momentum increases without bound as velocity approaches light speed — see relativity
• in quantum mechanics, momentum is quantized and related to wavelength via de Broglie relation
• angular momentum: rotational analog, conserved independently
• transfer of momentum is the mechanism of force