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Cross-sectional area for stress calculations

  1. Sep 17, 2011 #1
    I am having a lot of difficulty calculating the cross-sectional areas necessary for normal/shear stress problems. If the cross-section is a square or circle, I'm fine, but when the problem makes a diagonal section through the object I get really confused on which angle/trig function to use to calculate the cross-sectional area.

    Below are a few FBDs of problems I'm working on just to give a better idea of what I'm talking about.

    http://i53.tinypic.com/69fjvc.png
    http://i51.tinypic.com/2lji5ol.png
    http://i56.tinypic.com/2gv4fet.png
    http://i52.tinypic.com/2rrw094.png
    http://i56.tinypic.com/2e6a1qt.png

    Can someone please walk me through how to calculate cross-sectional area for these kind of problems (what angle/trig functions to use, etc)
     
  2. jcsd
  3. Sep 18, 2011 #2
    Treat the cross sectional area needed as the hypotenuse of a triangle. You know the angle theta. You know the leg A, which is the horizontal area of the figure.

    angle.jpg
     
  4. Sep 18, 2011 #3
    Thanks for the response. I think I am starting to get the hang of it.
     
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