Question

State law of conservation of momentum.

Answer 1

The law of momentum conservation can be stated as follows. For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision.

Hope it will help you

Answer 2

according to the law of conservation of momentum in the absence of net external force that is when external force equal to zero.
the initial Momentum equal to final momentum.or
in case of isolated system,p1=p1
where p1 &p2 are the initial and final momentum of an isolated system