Find the Young's Modulus of a Wire

[Reema]

A wire made of a particular material is loaded with a lod of 500 N. The diameter of the wire is 1mm. The length of the wire is 2.5 m, and it stretched 8mm when under load. What is the young modulus of this material?


My work

E= stress\strain

stress= F\A
r= d/2 ==> 1x10^-3 \ 2 = 0.0005
= 500\3.14 x (0.0005)^2 = 6.36x10^8

strain change in (L) / L
= 8x10^-3 \2.5
=3.2x10^-3

E= 6.36x10^8 \ 3.2x10^-3 = 1.98x10^11



BUT, the model answer is 2.5x 10^10 pa

 

[WatermelonPig]

Stress = P/A
= (500)/(3.14159*0.0005^2) = 6.366*10^8
Strain = (deltaL)/L
= 8/1 = 8
E = 8.295*10^7Pa
Are you sure you're giving the correct lengths? Where are you getting 2.5 from?

 

[Reema]

sorry, the length of the wire is 2.5 m