Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site druxu.UUCP Path: utzoo!linus!decvax!harpo!ihnp4!drutx!druxu!tll From: tll@druxu.UUCP (LaidigTL) Newsgroups: net.auto Subject: Re: 55 saves whot Message-ID: <928@druxu.UUCP> Date: Tue, 7-Feb-84 12:50:57 EST Article-I.D.: druxu.928 Posted: Tue Feb 7 12:50:57 1984 Date-Received: Thu, 9-Feb-84 22:04:59 EST References: <5465@decwrl.UUCP> Organization: AT&T Information Systems Laboratories, Denver Lines: 20 The article describing increased fuel use at higher speeds is generally good, but it does overstate the increase. As for getting better mileage at 80 vs. 60, BUNK. Drag goes up at the CUBE of velocity, so at 80 one would have to expend about 2.37 times as much fuel to overcome drag as one would at 60. Internal friction in the engine is non-linear also, being somewhere near the square of the engine speed. This implies about 1.78 time as much fuel. Although it is true that drag goes up at the cube of velocity, this means that energy needed PER UNIT TIME goes up as the cube of velocity. Since distance covered per unit time goes up linearly with velocity (How's that for an obvious statement?), energy needed per unit distance covered only goes up as the square of velocity. Similarly, energy per unit distance to overcome internal friction only goes up linearly with velocity. Tom Laidig AT&T Information Systems Laboratories, Denver ...!ihnp4!druxu!tll