i'm missing something...

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senorronaldo
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i'm missing something...

Postby senorronaldo » Sun Apr 11, 2010 4:38 am UTC

I need your brilliant minds...

if i managed to build a pipe from the bottom of the Mariana trench to the vacuum of space, how long would it take to empty the ocean if theres 1.3 billion cubic kilometers of water? (assuming no water would be caught in crevices etc..)

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Josephine
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Re: i'm missing something...

Postby Josephine » Sun Apr 11, 2010 4:40 am UTC

would that even work? Will gravity or pressure win out?
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senorronaldo
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Re: i'm missing something...

Postby senorronaldo » Sun Apr 11, 2010 4:42 am UTC

this is assuming it will work.

im going insane. i cant concentrate long enough to do the math

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ATCG
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Re: i'm missing something...

Postby ATCG » Sun Apr 11, 2010 4:46 am UTC

Bad assumption. Atmospheric pressure won't push a column of water more than about 33 feet (above sea level) up your pipe.
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senorronaldo
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Re: i'm missing something...

Postby senorronaldo » Sun Apr 11, 2010 4:48 am UTC

is it possible to do the math if we turn the laws of physics off?
i wont sleep till i get some answer.

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ATCG
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Re: i'm missing something...

Postby ATCG » Sun Apr 11, 2010 4:52 am UTC

Turn the laws of physics off and you can have pretty much any answer your heart desires. In any event, the diameter of your pipe is going to make a difference.
"The age of the universe is 100 billion, if the units are dog years." - Sean Carroll

senorronaldo
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Re: i'm missing something...

Postby senorronaldo » Sun Apr 11, 2010 4:54 am UTC

damn you logic and math.
destroying the dreams of my cough syrup effected mind.

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Re: i'm missing something...

Postby rflrob » Sun Apr 11, 2010 6:32 am UTC

It might just be possible if you take into account the evaporation. If I remember my junior year stat mech properly (which, btw, I probably don't), trees use a similar effect to get water to the tops of their leaves. I recall working some problem with chemical potentials and such, but I can't be sure until I get home and look it up.
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silent man
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Re: i'm missing something...

Postby silent man » Sun Apr 11, 2010 3:00 pm UTC

The only way I see this working is if the pipe was heated by some mechanism (either absorbed sunlight or active heating elements) to a point where the water vapor inside the pipe has a lower density than the air outside the pipe.
And even then I'd rather suspect that it's impossible to stretch this far enough to get out of earth's gravity well, so most of the water will eventually end up back here anyway.

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Diadem
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Re: i'm missing something...

Postby Diadem » Sun Apr 11, 2010 3:46 pm UTC

If the pipe is initially vacuum, the water would accelerate quite fast through the pipe, because it's under a thousand bars at the bottom of the Mariana trench. But as water shoots up the pipe, pressure on the bottom of the pipe increases until finally it's equal at the pressure just outside the pipe when the water has reached an altitude of 10 meters. Should the water level in the pipe should stabilize at a height of only 10 meters. How deep you stick the pipe into the water is actually irrelevant, only relevant is that the upper part is in space, so that there's no air pressure pushing the water down.

In our example though, the water will initially arrive at this altitude of 10 meters with a huge velocity. I'm too lazy to do the calculations, but I would not be surprised if some water made it into space initially. But after a while things should stabilize and no more water will leak out.

Of course, if you 'ignore physics' then all bets are off. If I ignore physics, how am I supposed to determine how much water goes through the pipe? If you give me this it's a simple matter of dividing the volume of the ocean by the volume of water transported through the pipe every second, to get how long it takes to empty the ocean.

But without applying the laws of physics, any figure for 'volume of water flowing through the pipe every second' will be entirely meaningless.
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opsomath
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Re: i'm missing something...

Postby opsomath » Mon Apr 12, 2010 1:18 am UTC

Oh me yarm! Someone told me that the ENTIRE ATMOSPHERE is _directly_ exposed to the vacuum of space! We're all gonna die!

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Coffee
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Re: i'm missing something...

Postby Coffee » Mon Apr 12, 2010 2:11 am UTC

Indeed the gravity of the situation is quite mind boggling.
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thoughtfully
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Re: i'm missing something...

Postby thoughtfully » Mon Apr 12, 2010 4:25 am UTC

opsomath wrote:Gee Willikers! Someone told me that the ENTIRE ATMOSPHERE is _directly_ exposed to the vacuum of space! We're all gonna die!

Sorry, just the outer bits.. which sort of fade gradually; there's no well defined surface. But the atmosphere you're breathing isn't exposed to space. Which you are probably grateful for.
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