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

["Bob Sciamanda" <treborsci@verizon.net>]

Given a perfectly spherical and homogeneous earth, the horizontal component 
of the centrifugal force would move earth stuff toward the equator, 
reshaping the earth's profile so that the normal force of rigidity can now, 
by itself, completely cancel both the gravitational and centrifugal forces.

-----Original Message----- 
From: Chuck Britton
Sent: Saturday, August 15, 2015 7:46 PM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] field of an ellipsoidal distribution

If your table were floating on the surface of a (quiet) lake, the water 
would not feel a (net) force toward the equator, nor would your air puck.

Right?

> On Aug 15, 2015, at 3:41 AM, Bob Sciamanda <treborsci@verizon.net> wrote:
>
> Forget the table and consider the forces on the material of the earth 
> surface itself.  It is this "horizontal" component of the centrifugal 
> force which moves earth stuff towards the equator to produce the bulge.
>
> -----Original Message----- From: Bob Sciamanda
> Sent: Friday, August 14, 2015 2:47 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] field of an ellipsoidal distribution
>
> 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).
>
> -----Original Message----- From: Carl Mungan
> Sent: Friday, August 14, 2015 2:37 PM
> To: PHYS-L
> Subject: Re: [Phys-L] field of an ellipsoidal distribution
>
> Hmm… define what you mean by a “horizontal” tabletop. Are you telling me
> that I should not expect a puck placed on a horizontal air hockey table to
> remain at rest?
>
> > On Aug 14, 2015, at 2:22 PM, Bob Sciamanda <treborsci@verizon.net> wrote:
> >
> > Carl wrote:
> > "The YouTube video neglects a small correction by assuming that N points 
> > in the
> > radial direction. This is the old question of “which way does a plumb bob
> > point” on a rotating earth point?  .  .  .
> >
> > Interesting ...  My spin is that the You Tube guy is not thinking of a 
> > plumb bob - he is modeling an object resting on a horizontal table top at 
> > the earth's surface.  Then his calculated N is indeed the normal force of 
> > the table top on his test object.  In addition there is required a 
> > frictional force from the table top to balance the horizontal component 
> > of the centrifugal force.
> > For a hanging bob model, the string must supply both components, as a 
> > single tension force (T, not N).
> >
> > Bob Sciamanda
> > Physics, Edinboro Univ of PA (Em)
> > treborsci@verizon.net
> > www.sciamanda.com
> > _______________________________________________
> > Forum for Physics Educators
> > Phys-l@www.phys-l.org
> > http://www.phys-l.org/mailman/listinfo/phys-l
>
>
> -----
> Carl E Mungan, Assoc Prof of Physics  410-293-6680 (O) -3729 (F)
> Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
> mailto:mungan@usna.edu     http://usna.edu/Users/physics/mungan/
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@www.phys-l.org
> http://www.phys-l.org/mailman/listinfo/phys-l
>
> Bob Sciamanda
> Physics, Edinboro Univ of PA (Em)
> treborsci@verizon.net
> www.sciamanda.com
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@www.phys-l.org
> http://www.phys-l.org/mailman/listinfo/phys-l
>
> Bob Sciamanda
> Physics, Edinboro Univ of PA (Em)
> treborsci@verizon.net
> www.sciamanda.com
> _______________________________________________
> Forum for Physics Educators
> Phys-l@www.phys-l.org
> http://www.phys-l.org/mailman/listinfo/phys-l

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Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
treborsci@verizon.net
www.sciamanda.com