Paper Towels and free energy?

wespelarno

wespelarno

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This has been making me think for a few days.

If you hold a paper towel so the plane of it is perpendicular to the ground (vertical) and dip just the end in a cup of water, the water is soaked up and the water moves up the towel due to capillary action. The water now has gravitational potential energy. Not much, but it does. Where does this energy come from? Does the water get colder? I doubt i've stumbled upon the solution to global power demand.
 
RYDA

RYDA

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Could it be an extreme case of diffusion where the paper towel is releasing energy as the water molecules are migrating through the concentration gradients, filling vacancies etc...

Ha, I have no clue... better go back to study!

EDIT:

Wouldn't the water loose kinetic energy as it gains gravitational potential?
 
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Richo 18

Richo 18

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RYDA said:
Could it be an extreme case of diffusion where the paper towel is releasing energy as the water molecules are migrating through the concentration gradients, filling vacancies etc...

Ha, I have no clue... better go back to study!

EDIT:

Wouldn't the water loose kinetic energy as it gains gravitational potential?
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Yeah, cause it was moving a lot in the cup before he sucked it into the paper towel. :p

The only thing I can think of is the attraction and intermolecular forces between water molecules that are being lost by separating them into the the sheet converts to gravitational potential. Cause water does attract to itself fairly readily because of the polarity of the molecule.
 
RYDA

RYDA

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Richo 18 said:
Yeah, cause it was moving a lot in the cup before he sucked it into the paper towel. :p
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The water isn't moving when its in the cup, but it does move up the paper towel, thus it has kinetic energy. As this kinetic energy I assume is slowly decreasing, this means that the gravitational potential would be slightly increasing.
 
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A

Arete

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RYDA said:
The water isn't moving when its in the cup, but it does move up the paper towel, thus it has kinetic energy. As this kinetic energy I assume is slowly decreasing, this means that the gravitational potential would be slightly increasing.
Click to expand...
Capillary action is caused by intramolecular attraction between molecules in a liquid, and will contiune until an equlibrium is met between gravitational forces and intramolecular forces for a given mass of water. It can be calculated using the Young-Laplace equation.

The problem with energy production is that you'll need an equal and opposite force minus ineffiency losses, to pull the water back down once it's ascended your capillary tube. Same as trying to harness the power or gravity - you'll need to put the water back up in order for it to fall again, eliminating any positive energy production in perpetuity unless you can get nature to do it for you (e.g. hydro dams).

BTW Einstein beat you to it by about 109 years :p

Einstein, A. Annalen der Physik, 1901, Folgerungen aus den Capillaritätserscheinungen, volume 4, page 513

Alright I'm going back to my laboratory, nehuik
 
3viltoast3r

3viltoast3r

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Arete said:
The problem with energy production is that you'll need an equal and opposite force minus ineffiency losses, to pull the water back down once it's ascended your capillary tube. Same as trying to harness the power or gravity - you'll need to put the water back up in order for it to fall again, eliminating any positive energy production in perpetuity unless you can get nature to do it for you (e.g. hydro dams).
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Now, going on bit of a secant here, but what if you cut a hole through the earth?
Disclaimer: Not necessarily a serious post :p
 
wespelarno

wespelarno

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Arete said:
Capillary action is caused by intramolecular attraction between molecules in a liquid, and will contiune until an equlibrium is met between gravitational forces and intramolecular forces for a given mass of water. It can be calculated using the Young-Laplace equation.

The problem with energy production is that you'll need an equal and opposite force minus ineffiency losses, to pull the water back down once it's ascended your capillary tube. Same as trying to harness the power or gravity - you'll need to put the water back up in order for it to fall again, eliminating any positive energy production in perpetuity unless you can get nature to do it for you (e.g. hydro dams).
Click to expand...
That and we will go through a lot of paper towels. To get the water back down, simply drop our immense paper towel onto a big plate attatched to a ratchet+pinion which spins a power generator. Then pick up a new piece of paper towel and repeat the process till the dam is full of paper towels.

I understand where the forces come from to make it happen, but does the young laplace equation account for energy the water gains as it moves up the towel?? It factors in surface tension in J/m^2.


The only kinetic energy it can really loose is heat, but it seems odd that a paper towel could have a spontaneous cooling effect.
 
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