Final answer:
The law of conservation of momentum states that the total momentum of interacting objects does not change. There are two possibilities in a collision: elastic and inelastic. In an elastic collision, both momentum and kinetic energy are conserved, while in an inelastic collision, only momentum is conserved. The law of conservation of momentum only applies if there is no net external force on the objects.
Step-by-step explanation:
The law of conservation of momentum states that the total momentum of interacting objects does not change. This means the total momentum before a collision or explosion is equal to the total momentum after a collision or explosion.
In the case of a collision, there are two possibilities. First, the objects can collide and bounce off each other, resulting in a change in their velocities. This type of collision is called elastic. In an elastic collision, both momentum and kinetic energy are conserved. Second, the objects can collide and stick together, forming a single composite object. This type of collision is called inelastic. In an inelastic collision, momentum is still conserved, but kinetic energy is not conserved.
The law of conservation of momentum applies to systems where there is no net external force acting on the objects. If there is an external force, like gravity or friction, then the momentum of the system can change.