# More hookes law question

groom03
[SOLVED] More hookes law question

## Homework Statement

i can't get the equation to work out to the right answer of 110-130Gpa

E=kL/A

k-1.45
L=2metres
A = 0.292cm

## The Attempt at a Solution

i get 0.0099Gpa

Homework Helper
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groom03
Sorry.

I've got to work out the Youngs modulus of a meterial using the equation k=EA/L which rearrnged to E=kL/A i know k because its the gradient of a force extension graph i made, A is the x-sectional area of the wire and L is original length of the wire. wiki says the youngs modulus of copper 110-130 Giga Pascals but i get something stupid like 0.009Gpa.

Homework Helper
Gold Member
Hmm. I'm thinking there may be some unit problems here if your off by that much. What are the units you are using in your calculations, including your graph?

groom03
I did some working on it today and i think you're right, I'm using newtons, millimetres and metres in the same equation, i converted all the units properly and I've got a more sensible answer now.

Homework Helper
Gold Member
I did some working on it today and i think you're right, I'm using newtons, millimetres and metres in the same equation, i converted all the units properly and I've got a more sensible answer now.

Good to hear. Sometimes it always boils down to something simple like the units.

groom03

Homework Helper
Gold Member
Anytime.