# Rotation in Mohr's circle

1. Aug 3, 2016

1. The problem statement, all variables and given/known data
for the τx'y' , i use the formula of -0.5(σx - σy)sin2θ + τxycos2θ , i found the ans is -41.3 rather than positive 41.3 , which part of my working is wrong? or I misunderstood something?

2. Relevant equations

3. The attempt at a solution

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2. Aug 3, 2016

here's the formula:

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3. Aug 4, 2016

after checking many times, I still couldnt find out the mistake

4. Aug 5, 2016

anyone can help ?

5. Aug 7, 2016

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6. Aug 9, 2016

bump

7. Aug 9, 2016

or it's wrong to use the transformation equation to do this question?

8. Aug 9, 2016

### Staff: Mentor

Unfortunately, it seems that you are not getting a response at the moment.

Have you looked at the "similar" threads listed at the foot of this page, to see whether something similar may have previously been discussed? Sometimes one can be lucky!

9. Aug 9, 2016

10. Aug 9, 2016

### Staff: Mentor

you scroll way down below here

11. Aug 9, 2016

no, i dont think i can find the answer for this question in other thread,can you help?

12. Aug 9, 2016

I have also used sin2(-θ) and cos2(-θ) instead of sin2(θ) and cos2(θ), but i still couldnt find the answer same as the author , which part of my working goes wrong
?

13. Aug 9, 2016

### Staff: Mentor

The topic is one I know nothing about, I'm sorry.

14. Aug 9, 2016