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| aidenlight |
 Posted: Wed May 14, 2008 5:38 am Post subject: Wondering if anyone could help me please? |
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Forum Freshman
Joined: 14 May 2008
Posts: 2
Location: Henley-on-Thames
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Hi, i'm a student and in stuck on a particular science question
Can anyone help me?
the question is as follows:
1. A 1 metre long strut (which is a straight rod) in a pin-jointed frame structure has a rectangular cross-sectional area of 8 sq cms, is subjected to a compressive load of 800 Newtons. If the value of Young's Modulus for the metal is given as 70 Giga-Pascals, find out what decrease in length occurs in the member?
Answers would be much appreciated 
Thank You
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(: Aiden  |
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| bit4bit |
| Posted: Wed May 14, 2008 6:03 am Post subject: |
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Forum Ph.D.
Joined: 14 Jul 2007
Posts: 625
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If E is Young's modulus, σ is stress, and s is strain
σ=Force/area = F/A
s=change in length/ original length = Δl / l0
E= σ/s = (F/A) / (Δl / l0) = F l0 / A(Δl)
then
Δl =Fl0/EA
Then just plug in, and calculate, and watch the units.
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Chance favours the prepared mind. |
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| Ophiolite |
| Posted: Wed May 14, 2008 6:09 am Post subject: |
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Forum Radioactive Isotope
Joined: 25 Jul 2005
Posts: 4858
Location: Scotland
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Aiden, welcome to the forum. I am assuming this is a homework problem. We discourage giving firect answers to homework. Perhaps if you can tell us how far you have got with the problem so far, what equation you think you might apply, or at least some indication of your thinking, then someone will be more than willing to offer you assistance.
I see bit4bit beat me to the submit key. 
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The Universe is not only weirder than we imagine it is weirder than we can imagine. J.B.S.Haldane. |
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| aidenlight |
| Posted: Wed May 14, 2008 6:16 am Post subject: |
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Forum Freshman
Joined: 14 May 2008
Posts: 2
Location: Henley-on-Thames
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Oh ok...sorry i'm new to this so i didnt know.
i have been stuck on this question for a while now and it has really started to bother me.
I really appreciate what bit4bit said because now i know where to start and i reckon i can now eventually work out the answer this isn't my strongest of topics 
sorry if i caused any bother
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(: Aiden |
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| bit4bit |
| Posted: Wed May 14, 2008 9:05 am Post subject: |
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Forum Ph.D.
Joined: 14 Jul 2007
Posts: 625
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My apologies Ophiolite 
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| Ophiolite |
| Posted: Thu May 15, 2008 1:24 am Post subject: |
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Forum Radioactive Isotope
Joined: 25 Jul 2005
Posts: 4858
Location: Scotland
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| aidenlight wrote: |
| sorry if i caused any bother |
No bother at all. Ask any questions at all, but for homework ones it is always best if you can explain a little what you have already tried. We get some people who come in expecting the answer with no effort. It is clear you are not one of those. So don't fret.
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