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From: hlh@linus.UUCP (Henry L. Hall)
Newsgroups: net.followup
Subject: Re: Fast driving
Message-ID: <620@linus.UUCP>
Date: Sat, 14-Jan-84 23:09:22 EST
Article-I.D.: linus.620
Posted: Sat Jan 14 23:09:22 1984
Date-Received: Sun, 15-Jan-84 02:46:45 EST
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Organization: MITRE Corp., Bedford MA
Lines: 33

Actually, I made my point about smaller cars going faster (say 65 mph) being
safer than larger cars going 55 mph a bit too general so I thought I'd clear
it up with a little math and specific examples.

I own a 1982 VW Scirocco, a fairly capable car able to be driven fairly
quickly and safely.  This car weighs 1978 lbs. or 987 kg. with me in it
(I weigh about 185 lbs.)  At 65 mph., the total kinetic energy is 
~2.965 * 10^9 Joules (I think that's the unit of measure for kg.*(meters/sec)^2)
A friend of mine has a 1978 Caddilac Coupe de Ville (yes, I don't determine
who my friends are just by the cars that they own :-), necessarily).  His
car weighs ~4000 lbs. or 1818 kg.  AT 55 mph, the total kinetic energy is
~3.911 *10^9 Joules.  Even if I'm incorrect in my units of measure (college
physics was "A Long Time Ago in a Galaxy Far Far Away...."), the point is
that his car has more kinetic energy travelling down the highway at 55 mph
than my car does at 65, E=m*v^2.

Further, and this is empirical data, my gas mileage on the highway is +35 mpg
while driving at about 65, ok, maybe even 70.  My friend luckily has a gasoline
company charge card, he can get 25 mpg going down a hill, with a tail wind, on
a clear day.......

Perhaps, as has been suggested in Car & Driver magazine, we ought to have
two different speed limits, one for cars under 2000 lbs. and one for those
that go faster, similar in spirit to the gas guzzler tax.  Too bad that it
would be so hard to enforce.

Perhaps we should also have a tax on overweight drivers, (more mass = more
kinetic energy) :-).

	Henry L. Hall

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