# Young's Modulus of wire

1. Dec 8, 2008

### Soojin

1. The problem statement, all variables and given/known data
"A brass wire with Young's modulus of 9.1 1010 Pa is 2.1 m long and has a cross-sectional area of 4.6 mm2. If a weight of 5.0 kN is hung from the wire, by how much does it stretch?"

The answer is to be given in cm.

2. Relevant equations

I used the equation for Young's Modulus, YM = (F/A) / ($$\Delta$$L/L0)

3. The attempt at a solution

I looked at my given info first.
YM = 9.1e10
Area = 4.6 mm2 = 0.46 cm2
Force = 5 kN = 5000 N
L0 = 2.1 m = 2100 cm

I converted all my units to cm because that's what the answer should be in.

Then I plugged that info into my Young's Modulus equation:

9.1e10 = [(5000)/(0.46)] / [($$\Delta$$L)/2100)]
$$\Delta$$L = (5000)(2100) / (.46)(9.1e10)
$$\Delta$$L = 2.5e-4

I thought I set this up right, but maybe I'm missing something.

2. Dec 8, 2008

### LowlyPion

I'd keep everything in meters.

Then convert for the answer.

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