When the mechanical properties of the system do not change then the system is in isolated state and it is called an isolated system. These systems are not interacting with environment and also called system with constant motion. The conservation laws are for isolated system because their properties are conserved and do not change. These laws are fundamental laws of mechanics in which the quantities like energy, angular momentum, and momentum etc. which are conserved quantities.
In the conservation law of energy, the energy is conserved and it is only converted from its one form to another form to make the total energy constant. Here, we discuss about the conservation of momentum in which the momentum of a system remains constant. Momentum is the mass in motion. It's equal to mass multiplied by velocity. So, it depends on two factors that are how much and how fast an object is moved.
So, in the conservation law of momentum, the sum of all object momentum remains constant in interaction within the system. It is true for all types of momentum like angular, linear etc. It is better explained by doing an experiment which is given as below
Law of Conservation of Momentum
The law of conservation of momentum states that the momentum will remain constant no matter what until and unless any external force comes into action.This results into the fact that the center of mass of the system of objects will move with the same or constant velocity unless and until it is being acted upon by external force.
The Conservation of momentum is mathematically the result of the homogeneity of space, i.e., conservation of momentum implies that the physical laws are independent of the position. Yet another consequence of the conservation of momentum is the Newton’s third law of motion that is the law of reciprocal actions. Let's take an example when a gun is fired if we assume that the initial position was at rest and hence the initial momentum to be zero the final momentum should also be zero according to the law of conservation of momentum.