For momentum to be conserved in a system it must
Momentum would be conserved.
The angular momentum of a system is not conserved when a net external torque acts upon the system.
Conservation of linear Momentum is independent of the coordinate system. It does not matter what coordinates are used. In a closed system, i.e. no external forces, momentum is conserved
Momentum of the system is conserved.Keep in mind kinetic energy of the system is not conserved
An isolated system can lead us to conclusion that the linear momentum is conserved. When the mechanical properties of a given system does not change, then the system is in an isolated state.
Total momentum in an isolated system does not change. The law of physics. The law of conservation of momentum explains that momentum is neither lost of gained. That means that there is a quantity, called momentum, that is conserved.
An angular momentum is the vector product which describes the rotary inertia of a system around its axis and is conserved in a closed system.
You say that momentum is conserved. This is always the case, if the system has no interaction with anything outside the system.
yes
A closed system
Angular momentum is the moment of momentum, a conserved vector quantity used to state the overall condition of a physical system.
In an isolated system the total momentum of a system remains conserved. For example If you fire a bullet from Gun , bullet go forward with some linear momentum and in order to conserve the linear momentum the gun recoils