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Homework Help: When calculating the shear stress, what should the area be?

  1. Oct 29, 2011 #1
    1. The problem statement, all variables and given/known data

    I'm looking at some problems and solutions to them, and when they calculate shear stress instead of having the area of the thing be pi*r^2, there is usually a (pi/4)*r^2.

    2. Relevant equations

    Shear Stress = V/A

    3. The attempt at a solution

    I don't understand where they get the 1/4 in the denominator.
  2. jcsd
  3. Oct 29, 2011 #2


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    You might want to review how shear stress is calculated. Your formula is not the usual one.
  4. Oct 29, 2011 #3
    I'm using and reading the chapter of shear stress in the book. That is what it tells me that shear stress is... Unless, I'm missing something.
  5. Oct 29, 2011 #4


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    The cross section area of a circular rod is (pi)(r^2) OR (pi)(d^2)/4
  6. Oct 30, 2011 #5
    Yeah, I figured it out. They gave the diameter in the problem so it was pi (d/2)^2. which is pi*(d^2)/4. I was stumped, but luckily i understand.

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