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« on: February 11, 2016, 10:02:07 PM »
Quick answer:
The surface of water simply takes on whatever shape leads to the lowest energy.
Take a big round tub on a turntable, part fill with water and rotate slowly. The water "piles up" around the edges.
On a Globe earth the natural surface of any body of water simply follows the "curve of the earth" (geoid if you want to get fussy).
There are many cases of small quantities of water taking on other shapes when surface tension comes into play.
But, there simply is no "Law" that says that the surface of water is a plane surface!
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Wouldn't the shape that leads to lowest energy always be flattening itself out? I don't understand how the tub metaphor relates to a spinning sphere though, shouldn't the water be trying to leave the surface if we're spinning 16000 mph? I know that water will not appear flat in a glass flask, because as you stated the surface tension will have an effect. I just figure there would have to be a way to measure even the slightest bit of curvature, say on a large lake with calm waters. If I make a circle in illustrator, then zoom into the max, a straight line would always have to be a tangent, couldn't this type of thing be detectable with even a small stretch of water?