How Much Does a Brass Wire Stretch Under a 5 kN Load?

[Soojin]

Homework Statement

"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.

Homework Equations

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

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)] / [(\DeltaL)/2100)]
\DeltaL = (5000)(2100) / (.46)(9.1e10)
\DeltaL = 2.5e-4

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

 

[LowlyPion]

I'd keep everything in meters.

Then convert for the answer.