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-   -   Is there water flow against gravity? (http://www.physicsforums.com/showthread.php?t=670905)

Jpacio Feb10-13 05:19 PM

Is there water flow against gravity?
 
Hi all,

I have been with this issue for some time and think I reached a conclusion but am not sure and was hoping that you guys could help me out with this.

http://spreadzed.com/water_flow/water.png

I was considering the scenario where you have a closed tube like the one you see in the image. Since there is no upper contact with atmosferic pressure, the water will not fall to the plate. It is also known that, from a specific height, the water column weight overcomes atmosferic pressure, thus allowing the water column to fall parcially. I have calculated that, for a specific atmosferic pressure of 10130 Pa, one would need a water column of 10.13 m to start producing vacuum.

Now, the doubt comes in this case: imagine that, for some reason, the water level goes below the 10.13 m (consequently, adding more vaccum to the top of the tube). Will actually atmosferic pressure force the water up against gravity until it reaches the height of 10.13m?

I hope I could explain this properly. Thanks in advance for your help guys :smile:

cjl Feb10-13 05:34 PM

Re: Is there water flow against gravity?
 
Yes, and that's exactly the principle behind a fluid-filled barometer (though they use mercury instead of water to reduce the fluid column height and vapor pressure).


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