Re: toroidal perpetual motion machine

[John Denker <jsd@MONMOUTH.COM>]

At 03:32 AM 6/30/00 -0400, Bob Sciamanda wrote:
> I don't really see a problem:

There's a real problem.  There's real physics here that has not yet been
elucidated.  See solution in following message.

> 1) The net downward meniscus force on the tube will be balanced by an
> adjustment in whatever force is supporting the weight of the tube (buoyancy
> if it is floating; normal forces of rigidity if it rests on a floor).

OK.  That applies to the total downward force, as distinct from the following:

> 2) The "toroidal shearing moment" will be resisted by stresses in the tube
> wall material.

What stresses are those?  The tube is supposed to be symmetric by
construction, and by symmetry any static stresses should be cancelled by
their mirror image.

(Dynamic stresses due to friction don't count, because they only arise when
the tube is rolling, i.e. the perpetual motion machine is already in full
operation.)

True fact:  you can buy toys consisting of a water-filled torus.  They are
amazingly slippery.  Basically you have to catch them by cradling them;  if
you just grab them they'll squirt away by performing the toroidal rolling
motion.