1. The problem statement, all variables and given/known data This is a fairly general problem that came up while trying to model a system. Given a rotating disk and an inertially fixed object, how is the fictional coriolis force handled? For example, if there is a dot on the ground below a sheet of transparent plastic rotating at speed [itex]\omega[/itex], does an observer on the sheet of plastic observe the coriolis affect, and why or why not? 2. Relevant equations The relevant subset of the relevant equation, aRotating = - 2[itex]\omega[/itex] x VRotating - [itex]\omega[/itex] x ([itex]\omega[/itex] x XRotating) 3. The attempt at a solution Well, the motion can be correctly described by the - [itex]\omega[/itex] x ([itex]\omega[/itex] x XRotating) portion of the equation. However, because there is apparent rotation, there is a VRotating, so - 2[itex]\omega[/itex] x VRotating is non zero, which makes no sense. I'm probably making a very simple mistake somewhere, and I suspect that it has to do with V being the velocity in the fixed frame, not the rotating frame, but all the explanations of the coriolis equation seem to state it with the velocity being from the rotating frame.