Momentum is a fundamental quantity in mechanics that is conserved in the absence of external forces. Conservation of momentum follows from invariance under translation by Noether's symmetry theorem. Eric Weisstein's World of Math A similar quantity conserved in the absence of noncentral forces is called angular momentum.
For a single particle of mass m with velocity v, the momentum is defined as
From Newton's second law, a force F produces a change in momentum
Therefore, if
and
so the particle has constant velocity.
Angular Momentum, Conservation of Momentum, External Force, Force, Impulse, Inertia, Mass, Momentum Commutator, Momentum Density, Momentum Four-Vector, Newton's Second Law, Velocity
