The Law of Conservation of Momentum is only valid in a closed system because:

Question

In a closed system, there are multiple velocities that can change in specific ways

In a closed system, only mass can be conserved

In a closed system, there are no additional forces or masses that can come in to throw off the momentum
values

In a closed system, net force has the ability to be calculated

Answer 1

The correct reason why the Law of Conservation of Momentum is only valid in a closed system is:

In a closed system, there are no additional forces or masses that can come in to throw off the momentum values.

This means that in a closed system, the total momentum remains constant because no external forces are acting on the system. If external forces were to act (as would happen in an open system), they could change the momentum of the objects involved, violating the conservation principle.