Description of conservation of momentum
A system is not subject to external forces or the sum of external forces received is zero, and the total momentum of this system remains unchanged. This conclusion is called the law of conservation of momentum.
1. The law of conservation of momentum is one of the most important and universal laws of conservation in nature. It is an experimental law, which can also be derived from Newton's third law combined with the theorem of momentum.
2. The system of things that interact with each other is called a system. The objects in the system can be two, three or more. When solving practical problems, the system should be selected reasonably according to the needs and the convenience of solving the problem.