# Young's modulus

1. Sep 20, 2015

### rgold

1. The problem statement, all variables and given/known data
The figure shows the stress-strain curve for a material. The scale of the stress axis is set by s = 280, in units of 10^6 N/m2. What are (a) the Young's modulus and (b) the approximate yield strength for this material?

2. Relevant equations
E=stress/strain

3. The attempt at a solution
so i know that for part a i needa divide 280/.004 but im not sure what it means to use units of 10^6. also shouldnt part b be 280? the unit that is correct is N/m^2 (its an online grading program that told me this is correct) and i cannot answer a 10^6 or any 10^.... (the system wont read it) what am i not understanding?

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2. Sep 20, 2015

### billy_joule

It means that if you enter [answer] this will be interpreted as [answer] x 106 N/m2
e.g. if you put in 6 your answer will be interpreted as 6 Mega Pascals

3. Sep 20, 2015

### rgold

so shouldnt the answer to part a be .07 n/m^2?

4. Sep 20, 2015

### billy_joule

What are the units of the '280' ?

What does 280 / 0.004 equal? What are it's units?

5. Sep 20, 2015

### rgold

280*10^6
so then the answer would be 7e10 but rly 7e4 bc of how the the program will interpret it?

6. Sep 20, 2015

### billy_joule

You still didn't provide any units but yes you are on the right track.

280 MPa / 0.004 = 70 GPa = 70 000 MPa = 70 000 x 106 N / m2

7. Sep 21, 2015

### rgold

so my final answer would be 70000e6 N/m^2 for part a and 250e6 N/m^2 for part b?

8. Sep 21, 2015