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Re: Why work before energy in texts



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.

*********************************************
"Karaoke bars combine two of the nation's
greatest evils: people who shouldn't drink
with people who shouldn't sing."

--Tom Dreesen
*********************************************
George Spagna
Department of Physics
Randolph-Macon College
P.O. Box 5005
Ashland, VA 23005-5505
phone: (804) 752-7344
FAX (804) 752-4724
e-mail: gspagna@rmc.edu
http://www.rmc.edu/~gspagna/