Re: curvature of buckets of water

[Gary Karshner <karshner@STMARYTX.EDU>]

Robert
> I have a question about "absolute rotation."  If one placed the bucket of
> water in the center of the rotating platform, one gets a curved surface.
> If one places the bucket of water off-center of the rotating platform, one
> also gets a curved surface but the orientation of the surface will be
> different.  Will the shape still be the same?  That is, if one is in the
> bucket's frame of reference, is there any way one can tell that the bucket
> is off-center rather than just "tipped over" (away from what appears to be
> the center of rotation)?

What do you mean by the same shape? It will still be a parabola, but the
focus will be at the center of rotation, i.e. the lowest water level in the
bucket will be as close to the axis as it can get.

> In a related matter, suppose one is trapped inside a box on a foreign
> planet. Is there an experiment that person can do to determine whether
> they are located coincident with the axis of rotation (i.e., north or
> south pole) rather than at some other latitude?

Here I think a Foucault pendulum would suffice, if it rotates 360 degrees
then you are at the pole but if it librates back and forth your not there.

Gary

Gary Karshner

St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU