# Easy stress/strain Q

Hullo. Hoping someone can help me with this Q off a statics past paper.
It's one of those things that I'm sure is ridiculously easy but I seem to be missing something (possibly very obvious.)
It's in the attatchment by the way.

my attempt:

strain = extension / o.g.length = 12 / 5000 = 0.003

E = stress / strain

therefore stress = E * strain = 210000 * 0.003 = 630

Which isn't a given answer so must be wrong. Can anyone please point out where I'm going wrong?

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Ooer managed to neglect actually attatch the problem. Here it is (I hope)

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You don't have any units but by the values you have listed I am assuming that they are metric, 12mm, 5000mm ... However, you should check your double check your math and your units.

Oh yeah, I was working in mm just because all of the potential answers were in mm so i figured it was easier to not have to convert at the end. If it was a unit error it would be out by a factor of 10 though wouldn't it?

If I divide 12/5000 = 0.0024. Check your math again.

Oops, that was a mis-type. the question says 15 mm, not 12 mm.
so it should say 15 / 5000 = 0.003

It's in the attatchment.
I dont know which one is correct but it has to be one of the given ones (400, -400, 14, -14 or 414 [all in N/mm^2])

Somethin's strange about those answers. Can't see the attachment, but are you doing shear stress by any chance?

I dont think the attatchment was working before, but it seems to be working now.

OK, I see the attachment, but still don't understand the answers. I think it must be a language thing, i.e., the question states the problem in a way that I'm not used to. I would understand it if we just hadn't jacked against the concrete. Please post the explanation when you get it; I'd love to see how I misunderstand this.

PhanthomJay