Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site LaBrea.ARPA Path: utzoo!linus!decvax!decwrl!Glacier!LaBrea!mann From: mann@LaBrea.ARPA Newsgroups: net.tv.drwho Subject: re: Re: TARDIS Mass (what is it?) [Full Circle] Message-ID: <129@LaBrea.ARPA> Date: Fri, 13-Sep-85 19:08:25 EDT Article-I.D.: LaBrea.129 Posted: Fri Sep 13 19:08:25 1985 Date-Received: Sun, 15-Sep-85 04:59:17 EDT References: <574@tellab1.UUCP> Distribution: net Organization: Stanford University Lines: 25 > > Kilograms are most definately a unit of WEIGHT . . . > You can shout as loud as you want, but that doesn't make you right. Please consult an introductory physics textbook before shooting off your mouth. Mass is a measure of (loosely speaking) the "quantity of matter" in an object, or its inertia. Weight is defined as the force exerted on an object by gravity. In a constant gravitational field, weight is directly proportional to mass. In the SI (metric) system, the basic unit of mass is the kilogram. Force (weight) is measured in newtons, where 1 nt = 1 kg-m/sec^2. In the English system, the basic unit of mass is the (little-used) slug. The basic unit of force (weight) is the pound. My engineer roommate tells me that the "pound of mass" (the mass of an object that weighs one pound in Earth's gravity at sea level) is more commonly used than the slug as a mass unit in the English system, just to make things more confusing. In common usage (since most of us spend all our time in a constant gravitational field), the terms "mass" and "weight" are used interchangeably, but there is definitely a difference. --Tim