Re: "Simple" pendulum

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

Last week Leigh Palmer wrote:

> ... A simple pendulum is not possible in a rotating frame
> because centrifugal force and gravity are not the only
> forces which act in that frame. Because the bob is
> moving the Coriolis force acts o push the bob out of
> the plane it would otherwise stay in.

Yes, the simple pendulum is not possible. But is it not true
that the Coriolis force is zero as long as the bob stays on
the same horizontal orbit (no air resistance and no friction).
OK, as I am reading the quoted sentence again I realize that
you were saying "if the bob strated to move toward another
angle THETA (as in simple pendulum) then the Coriolis
force would appear"?

I am still puzzled by the conical pendulum. The restoring
force is proportional to the distance from the axis of
rotation and the trajectory is circular. A circular orbit of
a stiletto, on the other hand, is due to a force which is
inversely proportional to the square of the distance r.
I know these are different systems, but  the often used
term "celestial clock" immediately brings to my mind
a clock controlled by a conical pendulum.

My misconception about the "elliptical" nature of
non circular trajectories of the bob was corrected in
this thread.

Ludwik Kowalski