Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Trouble analysing simple pin jointed problem

  1. Oct 29, 2011 #1

    I feel like I am overlooking some fundamentals when I am trying to solve/set up the equations to solve the following pin jointed problem. The only load on the system is at L. I ultimately need to solve all the reactions on the pins at A, B and the link at P (though I believe what is happening at P can be ignored when solving the forces at A and B).

    I am concerned about getting the signage right on my terms (+ or -) as well as simplifying some of the reaction forces at the pins. I also am getting confused when I try to reconcile and approach the problem by considering the element PBL by itself in a free body diagram.

    [PLAIN]http://img835.imageshack.us/img835/8058/problemfv.jpg [Broken]

    To make things more confusing I tried setting this problem up using WorkingModel 2D to try an set me straight but for some reason the answer I got from it just doesn't make sense. The reaction forces in the x direction don't see to add up to zero. Maybe I set up the problem incorrectly in the software?

    [PLAIN]http://img24.imageshack.us/img24/7528/forces.jpg [Broken]

    Thanks for any feedback.

    Last edited by a moderator: May 5, 2017
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted