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From: dgary@ecsvax.UUCP (D Gary Grady)
Newsgroups: net.physics
Subject: Re: Newman's Energy Machine (2)
Message-ID: <714@ecsvax.UUCP>
Date: Thu, 7-Nov-85 21:47:33 EST
Article-I.D.: ecsvax.714
Posted: Thu Nov  7 21:47:33 1985
Date-Received: Sun, 10-Nov-85 06:28:22 EST
References: <175@tulane.UUCP> <471@iham1.UUCP> <536@talcott.UUCP> <474@iham1.UUCP>
Organization: Duke U Comp Ctr
Lines: 18

>     It is unclear to me how potential energy contributes to an object's rest
>  mass.  All of the cases known to me, small though that may be, show that
>  mechanical potential energy is due solely to the location of an object within
>  some force field.

A wound-up clock, a charged battery, an excited atom ("It's New Year!"),
a hot rock all have more mass than their lower-energy counterparts
(after all, e does equal mc^2).  Whether the energy they represent
constitutes "potential" is a matter for definition.  The hot rock's
energy is kinetic, for example.  You might say that the charged battery
has chemical energy, but that energy is related directly to the
potential energies of the electrons.  Ditto for the wound-up clock or
the stretched spring (in your example).
-- 
D Gary Grady
Duke U Comp Center, Durham, NC  27706
(919) 684-3695
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