Hi, Dopers, can we get a debate settled here? Discussing the science-fiction Doc Savage stories, there’s doubnt whether or not water can be compressed.
In one story, our super-inventor Man of Bronze has developed a one-man submarine which compresses water for ballast, so that a small amount does the work as a larger amount.
Is this possible? As I understand it, if you try to compress water, you raise the temperature until you have steam actively trying to expand?
ALSO-- Is the water at the bottom of the ocean condensed? I think the harmful pressure is due to the sheer weight of the ocean pushing down, not that the medium itself is denser?
Can any of you folks settle this in a clear, easy to follow way?
Water can be compressed a very, very small amount. Not enough to store it in an appreciably smaller space, however.
Also, attempting to compress water by simply adding pressure will not turn water into steam. A gas is heated when compressed, but since you can’t compress water very much, you can’t add much heat to it this way.
You can compress anything made of matter. Generally, stuff is more empty space than actual stuff. You are correct that compressing something increases the temperature (but it does not increase the heat.)
With enough force, you could compress a bunch of water. You would then have lots of water in a small volume, which would be denser than water surrounding it, and the submarine would sink.
For the last part of your question, remember that compression and pressure are not the same thing. Compression happens because pressure is put on something. At the bottom of the ocean, there is a lot of pressure from the weight of the water above. This pressure causes the water (and everything else) down there to be compressed.
I’m no physicist…but my opinion is that it’s a matter of of how you interpret the question. For example, an “ice” cube is water, if you had it encased after it was already frozen, then let it melt, the remaining water wouldn’t take up all of the space in the container. By the same token, humidity in the air that collects on a cold glas could be looked at as being “condensed/compressed” from the surrounding air. I dunno, guess it’s just relative. I know this isn’t a “real” answer, but it’s just another point of view (as bad as it is).
Any matter can be compressed. We are just not capable of applying enough force on all sides of the matter to make the compression occur. We’d have hydrogen fussion by now, if it didn’t require equal force on all sides to compress matter into a smaller space. The weakest spot is where the compression would fail.
You’ve been voted the weakest link. Let’s remove the weakest link. Bye bye now.
V = V[sub]0[/sub][1 - B(p-1)]
Where V is compressed volume
V[sub]0[/sub] is volume at O centigrade and 1 atmosphere pressure
B is the coefficient of compressibility (atm[sup]-1[/sup])
B = 4.53X10[sup]-5[/sup] for water (1.10X10[sup]-4[/sup] for ethanol)
Pressure (Atm) H[sub]2[/sub]O volume (ml)
1 1000 ml
100 999.55 ml
1000 995.47 ml
1119 994.94 ml
The pressure reaches 1119 atmospheres 35798 feet beneath the surface; at the bottom of the Marianas trench. So a pressure of 16785 pounds per square inch (1119 X 15) will decrease the volume of water by about half of one percent. This number is for pure water; the salts and dissolved gasses in ocean water will make it slightly more compressible.
-Thank you, Castellan