# Rotation in Mohr's circle

## Homework Statement

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?

## The Attempt at a Solution

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here's the formula:

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

anyone can help ?

bump

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

NascentOxygen
Staff Emeritus
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!

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!

NascentOxygen
Staff Emeritus
you scroll way down below here [emoji652]

way down here [emoji652]
no, i dont think i can find the answer for this question in other thread,can you help?

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
?

NascentOxygen
Staff Emeritus