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Homework Help: Internal Forces in Statics

  1. Nov 7, 2004 #1
    Please Help! Internal Forces in Statics

    I have been attempting to answer the problems on my Statics assignment for about a week now but I have not been so success full. I have only be able to answer on of the problems the other three below I get stuck on. Can someone please help me get past the areas where I get stuck?

    The first question that I'm having trouble with can be found by following the link below
    http://herograw.com/7-20.JPG [Broken]

    My free body diagram looks like: http://herograw.com/fbd7-20.JPG [Broken]

    I'm not sure if that is the right the free body diagram and I am unsure as to how I can find the that largest virtical force. I'm wondering if I should leave the cable in the free body diagram that way its interaction is internal to the system and only have three unknown to find using [tex]\Sigma F_x = 0, \Sigma F_y = 0, \Sigma M_A = 0 [/tex]. Then I could go onto finding the internal normal force, shear force, and moment at the section C after I make free body diagrams for the section.

    The second question is: http://herograw.com/7-32.JPG [Broken]

    My free body diagram is:http://herograw.com/fbd7-32.jpg [Broken]

    In this question I am comming up with four unknowns (Ax, Ay, Cx, and Cy), but I only have 3 equations to use ([tex]\Sigma F_x = 0, \Sigma F_y = 0, \Sigma M_A = 0 [/tex]). I don't think member AB is a two force body because there is an applied load acting on it. I'm not sure as to what I should do finish this problem. I need to know what the reaction forces are before I can find the internal forces acting at the section point D.

    Lastly:http://herograw.com/7-40.JPG [Broken]

    This question confuses me. Could someone please clarify some as to what I need to do solve this question. I'm not sure how to make my free body diagram. I need a starting point and I can't seem to find one on my own.

    Someone please help. I have to get this done before Tuesday. I thank all who can help in advanced.
    Last edited by a moderator: May 1, 2017
  2. jcsd
  3. Nov 8, 2004 #2
    No one has any idea! I guess these questions are very difficult. Is there anyone who can help me in the least bit?
  4. Nov 8, 2004 #3
    :bugeye: :surprised I guess there is no hope after all... :cry: :mad: :grumpy: :yuck: :frown:
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