Question

A uniform steel wire X and Y, suspended at the same horizontal level, are connected by a light and cross-sectional area A, A weight of 30 N is placed at O, on the road OX : OY = 1 : 2. Both wires are stretched and the rod XY then remains horizontal.
If he wire X has a young modulus E1 of 1.0 * 10^11 pa, calculate the yound modulus of E2 of the wire Y assuming the elastic limit is not exceeded for both wires.

Answer 1

@Hero @Preetha @ghazi @AravindG

Answer 2

I think I saw a similiar question in NCERT text chapter 11 under topic of Young's modulus and all..take a look

Answer 3

can u give me the link of the book?

Answer 4

you are not from India?

Answer 5

nope

Answer 6

i suggest you google it..its easy to get NCERT CLASS 11 PHYSICS PART 2

Answer 7

do they have the solutions

Answer 8

yes i think .....

Answer 9

worth checking

Answer 10

infact the book is very nice for reference

Answer 11

http://www.vidhyarjan.com/news/ncert-solutions-for-class-11-physics

Answer 12

http://ncertbooks.prashanthellina.com/11_Physics.html

Answer 13

can u change the language?

Answer 14

ofcourse eng is below scroll down

Answer 15

gt it?

Answer 16

the question isnt there

Answer 17

Ok.. so since the xy is horizontal.. it means after stretching, both the bars have exactly the same length..

so i can say \[l1+\Delta l1 = l2 + \Delta l2 \]

next step we find the stress that is coming on each of them.. that should be easy.. since the ration of ox: oy is given to us..

Answer 18

can u show the working please:)

Answer 19

try doing it :P.. first you tell me how much will be the stress that comes on X and Y ?

Answer 20

stress = force/ area
how do i distrbte the force

Answer 21

first find the force.. force equals the weight that each one would experience..

the weight is at a ratio of 2:1 .. hence the distribution will be in inverse ratio right? 1:2.. cause if weight is far away, its effect is smaller!

Answer 22

hence Fx : Fy = 2:1

Answer 23

so now calculate Fx and Fy

Answer 24

Fx = 2/3 Fy
Fy = 1/3 Fx ?

Answer 25

total force is known to you.. so find the ratios now!

Answer 26

Fx = 2/3 Ftotal :P and Fy = 1/3 Ftotal

Answer 27

Fx = 20N and Fy = 10N

Answer 28

ok.. :D.. next.. find the stress on X and since young's modulus of X is given.. find the strain.. Similarly do the same thing for Y.. but young's modulus is not given.. divide the two equations to get rid of A

Answer 29

thanks alot
Strain = F/A*E1
strain in X = 20/A* 1.0 * 10^11

strain is equal so

E2 = stress/ strain
E2 = 10/A *A*1.0*10^11/20
E2 = 5 * 10^11 pa

Answer 30

woah wait.. how did you get the strain for Y ?

Answer 31

arent they equal

Answer 32

nope :-/.. why would the strains be equal?

Answer 33

same mterial

Answer 34

now you have to use the first equatoin.. that i put.. but use lx and ly notation instead of l1 and l2 notation

Answer 35

they are NOT SAME MATERIAL.. IF THEY WERE.. THEY WOULD HAVE SAME YOUNG"S MODULUS :P

Answer 36

i dont undrstnd >< cn u shw the working

Answer 37

use the first equation .. try doing it.. see you need to get rid of \[\Delta ly/ ly\] in that equation i asked you to build by dividing the two equations

Answer 38

so here are the two equations

\[Fx / Fy = Ex \Delta x ly / Ey \Delta ylx \]

and

\[lx + \Delta x = ly + \Delta y\]

somehow use them

Answer 39

ok il use thnks fr ur help :)

Answer 40

No problimo amigo :D