Re: floating a destroyer

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

At 11:18 -0400 8/1/01, Robert Cohen wrote:

> On the back of a box of vegetarian chili is the following "fantastic fact":
>
> The quantity of water that is used to produce a 1,000 lb. steer would
> <i>float a destroyer</i>.
>
> I have two questions:
>
> 1. Does it make sense the way it is worded?
> 2. I suppose they want to say the weight of the water is equivalent to the
> weight of a destroyer.  How did they figure out how much water is needed to
> produce a steer?

Funny you should ask. A problem almost like this is in Epstein's
"Thinking Physics," under discussion on another thread.

As usual with these "factoids" on cereal boxes, or other boxes,
someone got the whole thing so bolixed up that it is hard to figure
out what they meant. But, by looking at the problem (entitled
"battleship in a bathtub" as I recall) in Epstein's book, one can
easily see that, in principle, there is no lower limit to the amount
of water needed to "float" a destroyer. As long as the container is
large enough to hold the ship, the amount of water needed to float is
t is arbitrarily small, only being enough to  occupy the remaining
space in the container, once the "displaced" water is pushed aside by
the ship.

It would appear that the author of the food box factoid, has confused
the idea of how much water needs to be present to float the ship with
how much water the ship will displace as it floats. The two are
essentialy unrelated as long as the container can hold the ship
without it touching the container anywhere.

I would guess that one could estimate the amount of water needed to
produce a steer from the water consumption rates observed in feed
lots, or, if anyone bothers to keep such records, the water
consumption by a heard that mich  ght be confined in a closed area
(such as the way veal is raised). But consider this: Assuming that
the author of the factoid was loking for the amount of water
displaced by a destroyer, and looking at a typical early WWII
destroyer (the more recent ones are much larger--more ike the size of
a light cruiser of WWII vintage), about 2200 tons, and further
assuming that a steer has about a two year life span before he
becomes hamburger, that means that, if our authro is correct, to
raise a steer will take about 2200 tons of water, or roughly 3 tons
per day of its life. Now that is about 6 times its full-grown weight.
I'm not sure what all that water is used for. I doubt it is all for
drinking. If it is, I sure don't want to stand downstream of *that*
steer.

Hugh
--

Hugh Haskell
<mailto://haskell@ncssm.edu>
<mailto://hhaskell@mindspring.com>

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