lrb@hpcnof.UUCP (11/21/85)
Suppose a barge carrying a load of scrap iron is floating in one of the locks
of the St. Lawrence Seaway, patiently waiting for the Seaway to re-open.
(BTW, I heard last month on the news that it is to be closed for *months*
due to the wall of one lock collapsing, causing losses >$10M to certain
segments of the Canadian & U.S. economies). Anyway, suppose the crew of this
barge is Lithuanian, and after a few months of fruitless waiting they get
fed up (they don't have valid visas for either the U.S. or Canada, and so
neither country will let them step off the boat!) So they mutiny, and in a
gesture of defiance throw all the scrap metal overboard into the bottom of
the lock. The question:
Does the water level in the lock (in relation to the sides of the lock)........
a) .....go up?
b) .....go down?
OR
c) .....stay the same?
(Assume of course that both ends of the lock are closed to any movement of
water in or out, and it is in effect just a swimming pool.)
---Larry Bruns, ihnp4!hpfcla!l_bruns or hplabs!hpcnof!lrb
"Where, oh where are you tonight? Why did you leave me here all alone? I
searched the world over & thought I'd found True Love. You met another, and
*phthhhbt*, you was gone!"vsh@pixdoc.UUCP (Steve Harris) (11/27/85)
When the scrap iron is thrown overboard, the water level goes DOWN.
When the iron was in the boat, it displaced water equal to its own
weight. When it sinks to the bottom, it displaces water equal to its
own volume. Since the iron is denser than the water (it sinks), less
water is displaced and the water level goes down. (The rest of the
barge continues to maintain equilibrium).
Followup question:
The barge goes up relative to the surface of the water. However, does
the barge go up, down, or stay at the same level relative to the lock?
What information do you need to answer this question?
--
Steve Harris | {allegra|ihnp4|cbosgd|ima|genrad|amd|harvard}\
Pixel Systems Inc. | !wjh12!pixel!pixdoc!vsh
300 Wildwood Street |
Woburn, MA 01801 | 617-933-7735 x2314msb@lsuc.UUCP (Mark Brader) (11/30/85)
lrb@hpcnof.UUCP writes: > Suppose a barge carrying a load of scrap iron is floating in one of the locks > of the St. Lawrence Seaway, patiently waiting for the Seaway to re-open. > (BTW, I heard last month on the news that it is to be closed for *months* > due to the wall of one lock collapsing, causing losses >$10M to certain > segments of the Canadian & U.S. economies). The Seaway was closed for something like 3 or 4 weeks only. The lock is repaired and the traffic backlog should be cleared by now. At the time of the collapse, Seaway officials refused to speculate on how long it would be closed, so any reporters who said "months" (or "*months*") were simply guessing. Mark Brader, Toronto, Canada (about 100 km from where it happened)
lrb@hpcnof.UUCP (12/02/85)
ANSWER TO BARGE PROBLEM: Well, I've waited 3 weeks now, so here's the answer: While the iron is in the boat, it displace its *weight* in water; while the iron is in the lock, it displace its *volume* in water. Therefore, it displaces *less* water when it is thrown overboard, and so the water level goes *down*.
dim@whuxlm.UUCP (McCooey David I) (12/02/85)
> Followup question: > > The barge goes up relative to the surface of the water. However, does > the barge go up, down, or stay at the same level relative to the lock? > What information do you need to answer this question? It seems to me that you would need the following information: 1. volume of water in the lock 2. shape of the lock (i.e. do the walls rise vertically or at some angle or even in some other way?) 3. shape of the barge (i.e. is the hull more cone shaped or more square shaped?) 4. exact density and volume of the scrap iron Dave McCooey AT&T Bell Labs Whippany, NJ {ihnp4,decvax,seismo}!whlmos!dim