Re: [Phys-L] field of an ellipsoidal distribution

[John Denker <jsd@av8n.com>]

On 08/14/2015 11:47 AM, Bob Sciamanda wrote:
> Given a perfectly spherical rigid earth, and a table whose horizontal
> surface is perpendicular to the earth radius, the centrifugal force
> on an object resting on this horizontal surface has a horizontal
> component (very small in the real situation).

I'm with Carl on this one.

People have been living for a long time in places where 
the g vector is not aligned with the surface of the earth.

Generally, they are clever enough to define a "horizontal"
table to be one that things don't slide off of ... that
is, "horizontal" means perpendicular to the g vector  ...
emphatically /not/ perpendicular to the nominal radius.

  This is particularly obvious, given that it's incomparably
  easier to observe the g vector than the radius vector.

In practice, this means building lots of terraces.
  http://photos.travellerspoint.com/384816/agriculture_terrace.jpg

Even without a terrace, whenever I set up a table, I shim 
the legs to make sure that the table-top is "horizontal"
i.e. perpendicular to the g vector.