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From: sdp@omssw1.UUCP (Scott Peterson)
Newsgroups: sci.misc
Subject: Re: freshman physics
Message-ID: <198@omssw1.UUCP>
Date: Wed, 17-Dec-86 21:25:22 EST
Article-I.D.: omssw1.198
Posted: Wed Dec 17 21:25:22 1986
Date-Received: Fri, 19-Dec-86 04:51:53 EST
References: <4087@columbia.UUCP>
Reply-To: sdp@omssw1.UUCP (Scott Peterson)
Organization: Intel Corp., Hillsboro, OR
Lines: 26

In article <4087@columbia.UUCP> zdenek@heathcliff.columbia.edu.UUCP (Zdenek Radouch) writes:
>>Consider the following thought experiment:
>>
>>	Take 2 identical cars and place them nose to nose.  Rig the 
>>	accelerators of both so that you can give equal acceleration
>>	to each.  Now slowly increase the accelerations of the two
>>	cars.  Assuming that there is no slippage of the wheels, the
>>	cars will remain motionless....
>
>Note that if the cars are nose to nose (or as you pointed out motionless)
>you cannot "slowly increase the acceleration". They are not moving let alone
>accelerating. If there was no slippage of the wheels the engine couldn't run.
>You have to take care of conservation of energy even in a thought experiment.
>The work output of the engine can't just disappear. The cars are not moving
>so the energy delivered by the engine has to go somewhere else. The wheels
>must slip but the car will be motionless because the forces are balanced.

Unless the cars had automatic transmissions.  Then the slippage would
occur in the powertrain.  Engine output would become heat and motion of
hydraulic fluid.  The car with the best torque converter would win.

... but then maybe that's beyond the scope of the problem.

-- 

Scott Peterson, Intel Corp., Hillsboro, OR, ...!tektronix!ogcvax!omssw1!sdp