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Simple question about young's modulus 
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#1
Nov2812, 08:59 PM

P: 523

I did a practical worked the gradient and calculated E, of a wooden metre rule.
What I want is a value to compare my value with, I got 5 N/m^{2} So 5N will bend the ruler 1m? Seems likely right? 


#2
Nov2812, 09:09 PM

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Though your argument does not seem to match the units... Compare: http://www.madsci.org/posts/archives...3677.Ph.r.html ... and read the discussion: particularly about accuracy. 


#3
Nov2812, 09:10 PM

P: 523

On that page isn't that Mega Pascals?? I got 5Pa



#4
Nov2812, 09:12 PM

P: 523

Simple question about young's modulus
and maybe on that page those are MUCH higher maybe cause they calculated it using woods of greater thickness,length, etc.



#5
Nov2812, 09:18 PM

P: 523

Ohhhh LOL i'm sorry I didn't even see what I typed
my mind was away. I didn't mean 5 newtons would bend it 1m 


#6
Nov2912, 01:35 AM

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Would you get a higher modulus if you used a thicker beam?
It's a material property. How is the modulus defined? You can also look for other people who've done the same and talked about it. It's a common enough experiment  done either by vertical deflection by weights or by Timing harmonic motion. 


#7
Nov2912, 04:17 PM

P: 523

I found out my value is very wrong D: I need to recheck my calculations



#8
Nov2912, 04:35 PM

P: 523

I am so stupid =.= I left off a 10^8 somewhere in my calculations.
New value which makes sense NOW is 5.10 x 10^7Pa. 


#9
Nov2912, 04:43 PM

P: 523

Sigh again i was wrong I did it over again I got 5,108.1 MPa



#10
Nov2912, 09:32 PM

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When you have measurements on such a wide variation of scales, it is very easy to misplace lots of zeros :)
You can see from the discussion of accuracy in the article that these can get very big (as much as 56% it says) so you only need the right order of magnitude. "Conclude: Youngs modulus for a wooded meterrule was experimentally determined to be _____GPa. This agrees to the same order of magnitude as an accepted value of _____GPa given in ref. ______." If you did errors then you can also comment on how good the agreement was. 


#11
Nov3012, 05:41 PM

P: 523

Thank you.



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