Ok so here is the situation you are on a disc rotating with the same angular velocity at the center so you are in a rotating frame of reference. A block is placed.
The disc is frictionless. Here you would see ONLY the Coriolis force act.
The disc has friction and ONLY the centrifugal force acts.
So my question is when do we include centrifugal force and when do we include Coriolis force and when do both act together?