Re: A bawl in a rotating dish (was Hot air rising ...)

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

On Sun, 12 Sep 1999, Bob Sciamanda wrote:

> > . . .
> > 2. First some background...An object experiences a coriolis force when
> its
> > distance from the earth's axis changes.
> > . . . Robert Cohen
>
> Whence comes this dictum?
> The coriolis force is proportional to ( w x v ), where w is the rotational
> velocity vector of the earth, v is the subject particle's linear velocity
> in the earth frame, and x denotes a cross product.  This is not zero when
> v is tangential (ie., maintaining "a constant distance from the earth's
> axis".

As one important concrete illustration of this truth, consider the
appearance of a "stationary" object observed from a rotating reference
frame.  How could the rotating observers explain its circular trajectory
(and its unchanging distance from the axis) if not for the fact that the
Coriolis force (which is directed toward the axis of rotation) overwhelms
the centrifugal force?  In fact, the magnitude of the Coriolis force in
this case is precisely twice as large as that of the centrifugal force.

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm