Final answer:
The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it. This applies to any amount of objects within the system and is true for both elastic and inelastic collisions, although kinetic energy is not conserved in inelastic collisions.
Step-by-step explanation:
The law of conservation of momentum states that the total momentum of a closed system is constant if no external forces are acting on it. This principle implies that for a group of interacting objects, regardless of the number or the type of collisions (elastic or inelastic), if the system is isolated and not influenced by external forces, the total momentum before any interaction is equal to the total momentum after the interaction. In the case of inelastic collisions, while the total momentum is conserved, the kinetic energy is not, often resulting in objects sticking together post-collision and moving with a combined mass and velocity that still obey the conservation of momentum.
Application of the Law
In practical terms, if two objects of equal mass collide, one moving and one at rest, and no external forces are involved, after the collision, the previously moving object may come to rest while the other moves away with a velocity that ensures momentum conservation. An analysis of this scenario relies on understanding that total momentum, which is calculated as mass times velocity for each object, remains consistent before and during the impact.