Maximum height of steel rod before it tears under its own weight

[exibo177]

Homework Statement

Alright, so I have this final project in physics which was due yesterday and I'm turning it in late because i have a problem with understanding one thing.
so the project it about space elevators and the teacher asked me to make calculations about what is the maximum height of strongest modern material (steel) as a rod, until it tears itself down...

Homework Equations

I think of using the equation:
F/A=E*strain

The Attempt at a Solution

F/A for steel is 500x10^6
and E for steel is 200x10^6

i don't know how to calculate strain though, as i don't know initial length or change in length so could you please help me with this? with explanations

 

[PhanthomJay]

You don't need to look at the strain, only the stress, P/A. Look up the density of steel and caculate the length at which its breaking stress will be exceeded at the top of the rod.

 

[exibo177]

You don't need to look at the strain, only the stress, P/A. Look up the density of steel and caculate the length at which its breaking stress will be exceeded at the top of the rod.

Alright, but how do i calculate the breaking stress??

 

[PhanthomJay]

Alright, but how do i calculate the breaking stress??

I guess you can use the 500 Mpa value you listed.