Re: [math-fun] pile of sand constant
Joshua writes: << I read that the angle of repose for dry sand is about 30 degrees, but there are some other sites out there that tell me it depends on the grain size. . . .
If the grain size is roughly comparable to the particles of material that constitute the base surface (say, earth), it makes sense that the angle would depend on the grain size. But where the grain size is much larger than the particles making up the base surface (e.g., table salt on linoleum), I'd expect the situation would be virtually independent of the scale of the stuff being piled. --Dan
On 4/3/07, Daniel Asimov <dasimov@earthlink.net> wrote:
Joshua writes: If the grain size is roughly comparable to the particles of material that constitute the base surface (say, earth), it makes sense that the angle would depend on the grain size.
But where the grain size is much larger than the particles making up the base surface (e.g., table salt on linoleum), I'd expect the situation would be virtually independent of the scale of the stuff being piled.
Nope. There's more complicated stuff: cohesion depends on grain size (relative importance of surface area to volume), so I think there's a big difference. Take a look at http://www.wtamu.edu/~crobinson/SoilWater/mounddr.html for example. --Joshua
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Joshua Zucker