Length of wire with given yielding strength

[megr_ftw]

Homework Statement

A steel wire is being hung from a high altitude balloon. What is the greatest length is can have without yielding if the steel yields at 40 ksi??

Homework Equations

I know all the stress and strain equations but I have yet to find or be taught an equation for finding this. I feel like it's very simple but I just can't figure is out. Stress= force/area
Stress= (E-modulus)(strain)

The Attempt at a Solution

The answer is 11,800 ft or m, not sure which one. But I have no clue how to get to the answer. I did my homework and everything but this problem was "recommended" and I NEED to figure it out

 

[nvn]

megr_ftw: Hint: Wouldn't you want to compute the volume of the wire, and then the weight of the wire? Wouldn't the wire be carrying that weight?

 

[megr_ftw]

they don't give you the diameter so you can't calculate the volume

 

[nvn]

Could you let the diameter be d?

 

[megr_ftw]

oh yea i guess that would be the easiest option. as long as it cancels in the end.

The force of the wire's weight equals the buoyancy force created by the balloon right?

 

[nvn]

Yes, you could say that. Well said.