Question

In materials like Al and Cu, the correct order of magnitude of various elastic modulli is..?

Answer 1

they are asking among bulk,young's and shear.

Answer 2

on what basis i must decide..?

Answer 3

@shamim ?

Answer 4

Do u know abt stress

Answer 5

Strain?

Answer 6

If u hv a wire of cu

Answer 7

Let the length=L

Answer 8

yes i know how to calculate the three modulii

Answer 9

Hm

Answer 10

but they haven't mentioned that the length is same for both..

Answer 11

the only information we have is the name of the material.. which indirectly gives the mass..right?

Answer 12

and..Cu is heavier..but we have no clue abt length and volume which is required for all of them...

Answer 13

Sorry

Answer 14

no problem..

Answer 15

youngs modulus is a constant for a given material...
i think for Al its in the order of gigapascal (\(10^9\)Pa ).. u can google and verify

Answer 16

but how can we remember the values...? and what abt the other modulii?

Answer 17

ohh... sorry i misunderstood the question..
i found this in wiki
\[E=2G(1+ \nu )=3K(1-2 \nu)\]
E: youngs
G: shear modulus
K: bulk modulus
\(\nu\): poissons ratio

Answer 18

hope it helps :)

Answer 19

if you know any two of those values.. you can figure out the others

Answer 20

@baru ..thanks but how do i find the young's modulus without info on length..extensions etc..? could u help me in finding it...?

Answer 21

From my table on elastic moduli \(E\), I got this values:
copper---> \(E=108,000\;N/mm^2\)
aluminum---> \(E=68,700\;N/mm^2\)

Answer 22

which modulus is this i have to choose the order.. @Michele_Laino coz i have options like
young's>bulk>shear etc

Answer 23

@ParthKohli @samigupta8 @baru @Kainui

Answer 24

I think that it's a perfect memory based ans....lol...

Answer 25

Vidout knowledge of any quantity as such how can u arrive at the order of these moduli

Answer 26

how can we remember the modulii for all materials? its impossible..that too the time is limited..

Answer 27

Idk....bt seriously is it like that?

Answer 28

it came in an exam..

Answer 29

@ParthKohli ? any idea?

Answer 30

Ohh...i c....then i presume it was the test purely based on memory of the pupils....:)

Answer 31

@ganeshie8 @Farcher

Answer 32

they are the values for the Young's moduli @priyar

Answer 33

oh ok..how abt the other modulii..for ex: bulk modulus needs volume..can u tell me how to find the answer to this question? @Michele_Laino

Answer 34

@freckles can u help??

Answer 35

Question seems too physic-cy for me unless you can show me any math problem you came up with. I might be able to able you have that.

Answer 36

at present i am doing physics..so no math problem at the moment i have some more doubts in physics but i m not able to close this one as i didn't get the answer till now....

Answer 37

ok I was talking about any math problem that resulted from your physics question here, not unrelated math problems :p

Answer 38

oh..ok!

Answer 39

here are the ranges for densities of Aluminum and copper:
Aluminum---> \(\delta = 2560-2670\) \(Kg/m^3\)
Copper---> \(\delta= 8600 -8900\) \(Kg/m^3\)

Answer 40

please you have to consult a handbook of mechanics of machinery @priyar

Answer 41

@Michele_Laino but this was asked in an exam i don't think we are supposed to remember the values.