Re: Why work before energy in texts

[brian whatcott <inet@INTELLISYS.NET>]

At 07:36 10/17/01 -0400, George Spagna wrote:
> Ludwik writes:
>
> -----Original Message-----
> > From: Ludwik Kowalski [mailto:kowalskiL@MAIL.MONTCLAIR.EDU]
> > Most introductory textbooks teach that PEgrv = 0 can be
> > chosen arbitrarily at any distance between a particle and
> > the center of our planet. For example, at the sea level, at
> > the floor level, at the top of a laboratory table, at the roof
> > of that building, etc. A blunder or an apparent paradox?
>
> Operationally, it's neither a blunder nor a paradox.  The measurable
> quantity is the work done between two points, equal within a minus sign to
> the difference in potential energy.  The zero point is "arbitrary" because
> it cannot be uniquely measured.
...
> George Spagna

Nitpick alert:
George's arbitrary zero point has a non arbitrary inflection at sea level,
a feature exploited by Airy (1856) when he was measuring the Earth's mass
with a pendulum in mineshafts.


brian whatcott <inet@intellisys.net>  Altus OK
                Eureka!