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Homework Help: Find the Maximum (absolute) Vale of the Bending Moment

  1. Nov 15, 2012 #1
    1. The problem statement, all variables and given/known data

    Draw the shear and moment diagrams for the loaded beam. Then answer the questions. The distance x is measured from point A to the right.

    I have attached an image of the problem.

    2. Relevant equations

    3. The attempt at a solution

    I've managed to answer everything but the maximum bending moment correctly.

    What I've tried is to take a FBD of the beam from point A to somewhere in the region where the 570 lb/ft force acts. Then knowing that Ay = 1795.5 lb and that V =0 (V is the shear force) I calculated

    0 = -(570 lb/ft)(3.15 ft)(6.3 + 3.15) + M
    M = 33934.95 lb/ft

    But it says my answer is wrong and I'm at a loss as to what I'm doing wrong.

    Help would be greatly appreciated. Thank you.

    Attached Files:

  2. jcsd
  3. Nov 15, 2012 #2
    I just found my mistake. It should be:

    M = 570*3.15*(3.15/2 + 6.3)
    M = 14139.5625 lb.ft
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