Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site pur-phy.UUCP Path: utzoo!linus!decvax!harpo!ulysses!mhuxl!ihnp4!inuxc!pur-ee!CS-Mordred!Pucc-H:Physics:crl From: crl@pur-phy.UUCP (Charles LaBrec) Newsgroups: net.physics Subject: Re: eV Revisited Message-ID: <1198@pur-phy.UUCP> Date: Fri, 10-Feb-84 11:41:51 EST Article-I.D.: pur-phy.1198 Posted: Fri Feb 10 11:41:51 1984 Date-Received: Wed, 15-Feb-84 04:28:41 EST References: <1559@pur-ee.UUCP> Organization: Purdue University Physics Dept. Lines: 20 One of the first things you get used to in physics is differing unit systems. It is entirely possible (and in fact done) to devise a system of units where the unit of mass = the unit of energy. In relativity, you often see c = 1, and perhaps time in units of distance. In quantum electrodynamics, a frequent practice is to define hbar, c, and the mass of the electron = 1. One of the things that irks me sometimes is the variety of unit systems in electromagnetics. There are the MKS (SI), CGS(esu), CGS(emu), and Gaussian systems. Looking at more common systems, there are two English systems, one that uses "pound-mass" and the other "slugs" to measure mass. (I believe something that weighs 1 lb.-force has a mass of 1 lb-mass in the former.) Of course, a kilowatt-hr is a unit of energy (even though people commonly say, "How much power did we use?"). So, the bottom line is, don't hold unit systems sacred. Charles LaBrec UUCP: pur-ee!Physics:crl, purdue!Physics:crl INTERNET: crl @ pur-phy.UUCP