Normal strain of cable through arc

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coasterguy
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Homework Statement



See attachment

Homework Equations



eAB=(Lf-Lo)/(Lo)

The Attempt at a Solution



Ok, this is not for HW. I am preparing for a mechanics of materials class next semester. I don't understand when CB goes through the 0.3 degree arc, they say the height is still 300mm. Shouldn't it be slightly less than 300mm? If so, then I have only one angle and one non hypotenuse side, I can't figure out how to solve the rest of the new strained triangle.

Thank you!
 
Attachments
  • Textbook diagram of an airplane control linkage: a vertical rigid member CBD pinned at point A to a base, with cable AB running from A to B, a 400 mm horizontal dimension, 300 mm vertical dimensions, and force P applied at end D.
    2-8.JPG
    29.7 KB · Views: 582
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300 mm is not the height, it is the length of the part of the rod from B to C, which is unchanged after rotation. Then use the law of cosines as shown.