# My calculations - youngs modulus

1. Jan 31, 2012

### jokiemay

Im about to hand coursework in. Its the youngs modulus of copper wire

We added 100g weights and measured the extension using a traveling microscope.

for example at 0.900kg the wire extended by 6.36cm

my calculations are

Diameter = d 2.7x10-5 m
Cross section area A = Pi x d (squared) /4 = 5.7 x 10-8
Applied Force F = (mxg) 0.900 x 9.81 = 8.82 kg m s-1
Extension e = 0.0636 m
Original length L = 1.788 m

So Stress = F/A = 1.54 x 10(8)
Strain = E/L = 3.6 x 10-2

Stress / Strain = Youngs modulus E = 42 x 10(8) Pa

Does this look correct?

If i was to work out my mass / extension from my graph i would get this ...

m/e = 14.2 x (gxL) 17.5 / A 5.73 x 10-8 = 4.3 x 10(9) pa

Last edited: Feb 1, 2012
2. Jan 31, 2012

### TaxOnFear

Hi jokiemay,
I found it hard to understand what you're doing because you never really explained anything, you just have us a bunch of values. i.e. the cross-sectional area of what? What is 6.36cm? Is 0.9kg the mass of said object?

3. Feb 1, 2012

### jokiemay

ive edited the post above . thanks

4. Feb 1, 2012

### jokiemay

can anybody shine light on this ?