Thanks Steam Kining, think I've got it, just didn't read things correctly.
My last problem is that I've worked ot the SR to a colulumn as being equal to the ESR. My notes do not tell me how the column would fail in a case like this. Is there any other equation I should be looking at to find this...
Steam king Thanks for the reply, when using Eulers equation does it matter what units you use, should E be GNm-2 and I be Meters, or E be Nm-2 an I be mm, just not quite got my head round this bit.
How do we get the answer 3.84 x 10^6Nm-2
When I use my calculator I get
3.84 x 10^-4.
See attached PDF.
I guess I'm making a pretty basic error but I don't know what it is.
Thanks
Gavin