MadSci Network: Physics

Re: can water flow uphill withou a pump?

Date: Wed Sep 22 05:18:50 2004
Posted By: Kevin Kolb, Undergraduate, Physical Science, Cal Poly San Luis Obispo
Area of science: Physics
ID: 1095214949.Ph

Hello, Jesse.

The first law of thermodynamics states that energy cannot be created or destroyed, but only changed from one form to another. This is also called the conservation of energy. Elevating water increases its potential energy, so it cannot occur without other energy being expended. For example, an electrical water pump uses electrical energy to pump water uphill.

A siphon can make water flow uphill at first, but the location that it eventually drains to must be lower than the origin. The gravitational potential energy of the water in the downhill leg is used to raise the water at the beginning of the pipe or hose. The siphon must be started by drawing the water up through suction, but once it is started, the siphon will drain the water by itself.

The addition of silicon to the water would not allow it to flow uphill without a pump, and it isn't necessary for a siphon.

This is the point in the answer where I found the work of Manoj Chaudhury. He was able to make small amounts of water run uphill by varying the concentration of water repelling molecules on a silicon wafer. The water molecules traveled from the more hydrophobic (water repelling) side to the side that repelled water less, even if that path was uphill.

Later he made the droplets move faster by passing steam over the wafer. Here is a quote from an article in Space Daily. "Whereas before, Chaudhury could make the water drops move in only one way -- from point to point -- the increased energy created by the condensation now makes it possible to make the drops move radially, or out from the center of a surface, as well as up and down parallel channels, or columns."

However, energy is still being conserved. The increased gravitational potential energy comes from the thermal energy of the water molecules. The temperature of the water is lower after it travels uphill. The energy of condensation increased the speed of the water when steam was used.

Here are some links.

Waxy Races from Nature

Pushing Water "Uphill" Could Foreshadow Nanoelectronics from Science Daily

Thanks for your question, Jesse.


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