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From: hull@hao.UUCP (Howard Hull)
Newsgroups: net.physics
Subject: Re: Floating a battleship in a gallon of water
Message-ID: <1301@hao.UUCP>
Date: Wed, 12-Dec-84 09:46:59 EST
Article-I.D.: hao.1301
Posted: Wed Dec 12 09:46:59 1984
Date-Received: Fri, 14-Dec-84 05:37:59 EST
References: <27@daisy.UUCP> <6235@mcvax.UUCP>
Distribution: net
Organization: High Altitude Obs./NCAR, Boulder CO
Lines: 27

During the night it finally dawned on me what must be done.  Assuming that one
gets the battleship to float using any suitable configuration, it is possible
to place a valve in the connecting channel and close it without any resultant
redistribution of the forces.  After that is done, then we may indeed remove
the water and the battleship will continue to float in its gallon of water.
One way to avoid problems in teaching this would be to restate the principle
of Archimedes thusly:

	"If an object is freely suspended in a liquid, it is buoyed up
	 by a force equal to the weight of the displaced liquid, or its
	 virtual equivalent."

So as you can see, I AM STILL serious about requiring the 100,000 tons of
water to be there even if it is in a virtual form, or as you put it, not
"really" there.  Please let me apollogize in advance if I confused anyone
by my incomplete statement of the situation.

So now I have a question.  If we now wish to squeeze all of the water out of
the gap between the battleship and trough wall, what force pressing down on
the ship will be required to do so?  If we can get that question answered,
then we can find an answer to the original question in its proper context...
The original question was "how can the water hold up something greater than
its own weight".  This would seem to be a question of fundamental structure
were it not for the degree of freedom allowed by the width of the space
between the ship and the trough.
						Regards,	Howard Hull
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