User:William M. Connolley/motion in a rotating system

This is a page, sort of notes for myself, and perhaps one day a wike page.

If you feel inclined to comment, please refraim for now. Its just starting.

Coriolis effect and its discussion refers, as does http://www.physics.oregonstate.edu/paradigms/Publications/GreatCircles.html. CT gets some credit for forcing me to think about this, as does PB.

First, and perhaps foremost, the problem at issue is to understand how an object, moving without imposed forces in an inertial system, moves when viewed in a rotating system (this is all in Newtonian dynamics, so that makes sense). This is on the (correct) assumption that we understand how it moves (F=ma) in an inertial system. There are essentially two ways of doing this. The first (which I prefer) is simply to say that in a rotating system two forces (the Coriolis and Centrifugal) appear, and when these forces are added to the equations of motion the correct motion is predicted. The second is to say, that looking from "above" from an inertial system we can explain that a rotating observer sees "apparent" motion. The second version appeals to some, but runs the risk of becoming distinctly wordy and qualitative. Of course, both view must in the end be equivalent.

Note also that there are similarities and differences between the dynamics of motion on a turntable and on a sphere(oid), the second being more complicated.

Motion on a turntable
A flat frictionless turntable rotates, with observer R at rest upon it. Observer I is at rest in an outside inertial system. A particle is placed on the turntable (not on the rotation axis), initially at rest as seen by I. It therefore remains at I_rest. From R, it therefore moves in a circle.