At last, a use for my copy of The Physics of Blown Sand and Desert Dunes (R.A. Bagnold, Dover reprint) On pg 1 he introduces a partially overlapping continuum of particles (big to small) Pebbles Sand Dust Fog Particles Atmospheric Dust Thin Smoke Haze Pebbles are for him 1mm or greater in diameter. "Sand" occupies the region from 1mm down to 1/50 of a millimeter. You hit the "Dust" boundary there.
From pg 6
"When samples of natural sand are analyzed by sifting, it is found that, in general, grains of one diameter predominate, and that the weights of sand of diameters both larger and smaller fall off rapidly as the diameter departs from the "peak" value. And in the finest wind-blown sands the predominant diameter is never less than .08mm. Usual values, depending on the locality, lie between 0.3 and 0.15mm." On Mon, Nov 1, 2010 at 1:28 PM, Robert Munafo <mrob27@gmail.com> wrote:
Simon,
Isn't there a power law distribution of some kind with larger and smaller grains intermixed?
Compare the definitions of "sand", "silt" and "clay", or look up "sediment grain sizes". Example: http://geology.about.com/od/sediment_soil/a/sedimentsizes.htm
On Mon, Nov 1, 2010 at 13:00, Simon Plouffe <simon.plouffe@gmail.com> wrote:
Hello ,
I read recently that the calculated the approx. amount of stars in the known universe to be 7x10^22, which is according to source, greater than the number of grains of sand in all the deserts and beaches on earth.
Well, this is quite big, but as I was explaining this to some people around me,
is there a known value of the number of grains of sand in let's say 1 cubic meter of sand ? I know some are very small and others are bigger : does someone has an approximate value ? I tried to find without success and also I have no idea on how to calculate this simple value.
Thanks for any answer(!).
source : a certain australian study : http://en.wikipedia.org/wiki/Observable_universe
best regards and have a nice evening.
Simon Plouffe
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