I'm trying to solve the problems on this page:(adsbygoogle = window.adsbygoogle || []).push({});

http://physics.uwstout.edu/StatStr/statics/StatII/statp21f.htm

The second last one is a bit hard for me, but I think I've got it. Just need to get my approach confirmed as correct. I first found the external support reactions, that went fine.

Then, to determine the force in CD, I first drew an FBD (free body diagram) of member ABC placing two uknown forces at point B (Bx and By) and the one given force at C (should I have placed two unknown forces here also, Cx and Cy ?). Solving this I found the values for Bx and By.

I now drew a new FBD for member BD, placing two new unknown forces (Dx and Dy) in point D along with the given force in the middle, the known force E, and Bx and By (which I found earlier) in point B. Solving for Dx I got the correct answer of 9000 lb, but is my approach valid, or was this just coincidence?

Any help will be appreciated...

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# Homework Help: Simple statics

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