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In [http://en.wikipedia.org/wiki/Classical_mechanics classical [mechanics], '''momentum''' (pl. momenta; SI unit kg·m/s, or, equivalently, N·s) is the product of the [[mass]] and [[velocity]] of an object (p = mv). It is sometimes referred to as linear momentum to distinguish it from the related subject of angular momentum. Linear momentum is a [[vector]] [[quantity]], since it has a direction as well as a magnitude. Angular momentum is a pseudovector quantity because it gains an additional sign flip under an improper rotation. The total momentum of any [[group]] of objects remains the same unless outside [[force]]s [[act]] on the objects (law of conservation of momentum).

In [http://en.wikipedia.org/wiki/Classical_mechanics classical mechanics], '''momentum''' (pl. momenta; SI unit kg·m/s, or, equivalently, N·s) is the product of the [[mass]] and [[velocity]] of an object (p = mv). It is sometimes referred to as linear momentum to distinguish it from the related subject of angular momentum. Linear momentum is a [[vector]] [[quantity]], since it has a direction as well as a magnitude. Angular momentum is a pseudovector quantity because it gains an additional sign flip under an improper rotation. The total momentum of any [[group]] of objects remains the same unless outside [[force]]s [[act]] on the objects (law of conservation of momentum).

Momentum is a conserved quantity, meaning that the total momentum of any closed [[system]] (one not affected by external forces) cannot [[change]]. This law is also true in [[special relativity]].

Momentum is a conserved quantity, meaning that the total momentum of any closed [[system]] (one not affected by external forces) cannot [[change]]. This law is also true in [[special relativity]].