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tigerwoods99
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Homework Statement
A 20.0 m long uniform beam weighing 670 N is supported on walls A and B, as shown in Fig. 9-77.
http://www.webassign.net/giancoli5/9_77.gif
(a) Find the maximum weight a person can be to walk to the extreme end D without tipping the beam.
(b) Find the forces that the walls A and B exert on the beam when the same person is standing at point D.
(c) Find the forces that the walls A and B exert on the beam when the same person is standing at a point 2.0 m to the right of B.
(d) Find the forces that the walls A and B exert on the beam when the same person is standing 2.0 m to the right of A.
I figured out A + B but not C and D.
Homework Equations
sigma Fy = 0
sigma FTorque = 0
The Attempt at a Solution
FA = beam A
FB= beam B
mg= mass of beam * 9.8
FC= the person
a) 670N
b) 0 N from wall A and 1340N from wall B
C) using FA as the pivot: 0FAsin90 + 12FBsin90 -8.5mgsin90 - 15FCsin90 = 0
12FB - 15745 = 0
FB = 1312.08 WHICH IS NOT CORRECT.
D)