Question

why is the maximum height of mountain on earth ~10km ??answer by considering elastic properties of rocks

Answer 1

Interesting question. Have a look at this:
http://www.ias.ac.in/jarch/jaa/2/165-169.pdf

Answer 2

hmm james thats long one

Answer 3

could u simplify?

Answer 4

my text has answered it in a small paragraph but i didnt get it :(

Answer 5

my text has answered it in a small paragraph but i didnt get it :(

Answer 6

what is the basic idea here?

Answer 7

The question is when does the pressure of the weight of rock above the base create such a large sheer force that the base crumbles. That's the first equation in the paper

\[ h \approx 4Y/\rho g \]

Calculate that height for a Young's modulus Y and density \( \rho \) of rock and see what you get.

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Meantime what did your paragraph say?

Answer 8

:P lemme try to post it here

Answer 9

:P lemme try to post it here

Answer 10

srry i dont hav a scanner!

Answer 11

Right ... that's the answer! What don't you understand there?

Answer 12

wel i am confused

Answer 13

wel i am confused

Answer 14

Well, first you should know that the pressure of a column of material of height h and density rho is
P = rho.g.h

Familiar?

Answer 15

Now, if you stack up any material, bricks say, there will be a point where the pressure of the mass of material above the base will create such a large shear force on the base, that the material at the bottom shears off or collapses.

Answer 16

That's what this paragraph is calculating: for what height of rock will those forces be sufficiently great that the force at the bottom causes a collapse.

Answer 17

The elastic limit of the rock was imbedded in the book's conversation in that number they cite as the elastic limit. This is the part of elastics where materials 'flow' because the pressure is so great. Hence when they cite that number, there's been some sort of experiment in the background where that number was found. It's not obvious that you can calculate that number theoretically, although it could be approximated.

Answer 18

You might find it helpful to watch this lecture and the amazing demonstration to see where the 'flow' comes about in straining a material:
http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/lecture-26/

Notice that the shape of the curve for every material varies and while the general shape and phases are the same across materials, it's not fixed in shape and hence to find the 'flow' phase for rock would require an experiment.