Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/17/84; site mhuxt.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!js2j From: js2j@mhuxt.UUCP (sonntag) Newsgroups: net.physics Subject: Re: Potential Energy (could someone expand on the 'yes' answer?) Message-ID: <1235@mhuxt.UUCP> Date: Mon, 4-Nov-85 13:04:22 EST Article-I.D.: mhuxt.1235 Posted: Mon Nov 4 13:04:22 1985 Date-Received: Tue, 5-Nov-85 23:11:53 EST References: <175@tulane.UUCP> <471@iham1.UUCP> <536@talcott.UUCP> <1514@teddy.UUCP> <1076@jhunix.UUCP> Organization: AT&T Bell Laboratories, Murray Hill Lines: 23 > >Is this true? Does the potential energy stored in a spring > >contribute to its rest mass? How about a battery, a capacitor, etc? > >-> Jim Galbiati, GenRad Inc, Production Test Division <- > > Yes. Wow, what an informative answer! Lets consider a very simple system as a specific example. Suppose we have two electrons rather close together and very far from any other influence at T=0. They have some potential energy stored by virtue of their mutual repulsion. If we let them go, that potential energy is gradually converted to kinetic energy as they speed apart. If we could measure the mass of these electrons, would we find that the two-electron system has more than two electron rest masses? Would we find that each electron has more than one electron rest mass? If we were measuring the electron masses from the reference frame stationary w.r.t. the electrons at T=0, would the extra mass measured as T => infinity be the same as the extra mass measured due to relativistic effects, or would we have to treat that apparent mass change seperately? -- Jeff Sonntag ihnp4!mhuxt!js2j "What would Captain Kirk say?"