If a part of a system’s rotation axis change with time, but there is no external torque,
1. Can apply conservation of momentum of this system?
2. Can apply conservation of momentum of that part of the system?

:confused:

If a part of a system’s rotation axis change with time, but there is no external torque,
1. Can apply conservation of momentum of this system?

Yes.


2. Can apply conservation of momentum of that part of the system?


Not sure what you mean - please clarify.

Yes.



Not sure what you mean - please clarify.

This is the question,
One end of a thin inelastic string of a length l was attached to a small object of mass m resting on a friction less horizontal surface and other end is fixed to a point on the surface of a vertical uniform solid cylinder of radius r and mass M, which can freely rotate about its vertical axis through its centre. Now a velocity v is given to mass m in perpendicular to string. What is the angular momentum of the system about cylinder’s rotating axis when mass hit the cylinder?

this is the question,
One end of a thin inelastic string of a length l was attached to a small object of mass m resting on a friction less horizontal surface and other end is fixed to a point on the surface of a vertical uniform solid cylinder of radius r and mass M, which can freely rotate about its vertical axis through its centre. Now a velocity v is given to mass m in perpendicular to string. What is the angular momentum of the system about cylinder’s rotating axis when mass hit the cylinder?

If anyone want more details please ask
:confused:

[QUOTE=ebaines;2114263]Yes.

Can apply whole system, about which axis?:confused: