Question

linear momentum of a body is conserved only if​

Answer 1

Answer:

The law of conservation of momentum says that the momentum of a closed system is constant in time (conserved). ... The total momentum of a system is conserved only when the system is closed.

Answer 2

Answer:

The law of conservation of momentum says that the momentum of a closed system is constant in time (conserved). A closed (or isolated) system is defined to be one for which the mass remains constant, and the net external force is zero. The total momentum of a system is conserved only when the system is closed.