Young's modulus calculation for brass wire stretched by 1 kN

[KaneOris]

Youngs Modulus

Hey guys, i tried this problem on youngs modulas and got the wrong answer

So i was wondering if anyone could tell me where i went wrong here or tell me how to do it properly.

Problem:

A 20cm brass wire of radius 1.0mm
experiences an elongation of 0.49mm
when a tensile force of 1.0 kN is applied.
Calculate the youngs modulas of brass.

E=σ/Є
σ = F/A
Є=ΔL/L

F=1000 N
A=0.2*0.001
ΔL=4.9*10^-4
L=1.0*^-3

Є = 4.9*10^-4/1.0X10^-3
σ = 1000/0.2*0.001
E= (1000/0.2*0.001)/(4.9*10^-4/1.0X10^-3)
That came out as 1.0*10^7 for me.
The answer is apparently 1.3*10^11

Any help on this would be good.

 

[dextercioby]

The cross sectional area is wrong...

Daniel.

 

[KaneOris]

mmm, wires, 3.142r^2...

 

[dextercioby]

Yep,that's right.And the length L is wrong as well.

Daniel.

 

[heman]

calculation mistake rather than conceptual mistakes..