Find the Maximum (absolute) Vale of the Bending Moment

1. Nov 15, 2012

Northbysouth

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

ƩMA=0
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.

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• Statics hwk 20 5.136.png
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2. Nov 15, 2012

Northbysouth

I just found my mistake. It should be:

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