Quasi Static or Include inertial Terms

Hi everyone,

I'm creating a breast model in order to study the effect of the gravity force. I've used time stepping with the adaptive time step provided by COMSOL, and increase the gravity progressively from zero at initial stage to g in a physical time of 60 s.

I note that my results changes if I select "Include inertial Forces" or if use "Quasi-static" option. Could you help me trying to explain which is the best choice for my case?

Thank you so much, Maria