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Summary:
 A statics question regarding a twomember frame.
For this problem (see image), I get the correct answer for the normal force at point E if I:
1) divide the frame into members AB and CB,
2) solve for the x and y components of the reaction force at point B,
3) make a free body diagram with the cut at point E forming member EB and setting the sum of the xcomponents of the forces to 0 and solving for the normal force.
BUT
If I try to solve it by treating the two members as a system (and, thus, discount the reaction force at B), setting the sum of the moments about point A to 0 and then solving that for the xcomponent of the reaction force at point C which would then equal the the negative of the normal force at point E, I don't get the same answer. Why is that?
1) divide the frame into members AB and CB,
2) solve for the x and y components of the reaction force at point B,
3) make a free body diagram with the cut at point E forming member EB and setting the sum of the xcomponents of the forces to 0 and solving for the normal force.
BUT
If I try to solve it by treating the two members as a system (and, thus, discount the reaction force at B), setting the sum of the moments about point A to 0 and then solving that for the xcomponent of the reaction force at point C which would then equal the the negative of the normal force at point E, I don't get the same answer. Why is that?
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