I missed a class and now I am having some trouble understanding whats going on. I am trying to solve for the components of forces in the truss and whether they exert a compression force or a tensile force. I have attached an image taken from my book and the free body diagrams provided by the book for the truss in question. The question is long and painful but I will really appreciate it if you help me out(adsbygoogle = window.adsbygoogle || []).push({});

*In the diagram forces F and angles θ are the same. There are pin joints at all the points labeled*

The FBD drawn at A looks alright. Fairly easy to to find the direction of the forces in those trusses just be inspecting it. The FBD drawn at C is where things start to get confusing. First of why did the vector CD switch directions? Since CD switched directions as a result so did BC which means that there is now a compression force acting on BD. If CD had remained the same direction as it was in the FBD drawn at A then there would have been a tensile force along BD. Another thing that bothers me is that the effects of the horizontal component of ED was cancelled out by CD in the first diagram so why does CD show up again? Pretty much all of the same questions arise again in the last FBD. I forgot to label some parts in the last diagram so lets just leave it be as if I understand the second diagram I am confident I will understand the third one as well.

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# Trouble understating Trusses

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