Conservation of momentum question

[overtak3n]

Hello, can someone explain to me this question:

A woman holding a large rock stands on a frictionless, horizontal
sheet of ice. She throws the rock with speed Vo at an angle α
above the horizontal. Consider the system consisting of the woman
plus the rock. Is the momentum of the system conserved? Why or
why not? Is any component of the momentum of the system conserved?
Again, why or why not?

The way I understand it is there is no loss in momentum since there are no external forces. No?

 

[Basic_Physics]

What about the normal force acting on the woman.

 

[overtak3n]

I believe the normal force changes as she throws the rock, so the vertical component changes?

 

[Basic_Physics]

Yes. This component of their combined momentum will change.

 

[overtak3n]

Does gravity working on the rock also indicate that the vertical component isn't conserved?

 

[Basic_Physics]

Yes it is also an external force as far as the system is concerned. It is a force that originates from something that is not part of the system.

 

[overtak3n]

Okay, thanks for the help!