Calculating percentage uncertainty for young's modulus

AI Thread Summary
To calculate percentage uncertainty for Young's modulus, one must first determine the uncertainties in measurements used to calculate stress and strain. The formula for Young's modulus involves stress (force applied divided by cross-sectional area) and strain (extension divided by original length). To show reduced uncertainty in a second method, compare the overall uncertainties from both methods by calculating the percentage uncertainty for each. The user has expressed gratitude for the assistance received and has successfully figured out the calculations after some effort. Understanding the theory behind these calculations is crucial for accurate results in coursework.
Hallam17
Messages
2
Reaction score
0

Homework Statement



I cannot work out how to calculate my percentage uncertainty for my coursework, i need to show that my second method has a reduced uncertainty than my first, could anybody please enlighten me as to how to work it out. My table for one of the practicals is attached

Homework Equations



You probably know this already but just in case

∏d2 = cross sectional area
Extension/Original Length = Strain
Force Applied/Cross Sectional Area = Stress
Young's Modulus = Stress/Strain

The Attempt at a Solution



Tried numerous times but quite simply don't understand how to get an overall uncertainty for the practical

I would also like to add that as stated in the 'why hasn't anybody answered me' thread it's the theory that I'm after not for you to do the homework, I understand how that could irritate those helping on here

Any help would be greatly appreciated, thanks
 

Attachments

  • Young's Modulus Table.jpg
    Young's Modulus Table.jpg
    49.8 KB · Views: 1,712
Last edited:
Physics news on Phys.org
After refreshing this page for 2 hours, I tried yet even more possibilities and have figured out how to do this now!
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top