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Homework Help: Rigid Body Equilibrium Question

  1. Nov 24, 2009 #1
    Hi, I have a question regarding Equilibrium problems.
    Here is the example of my hw.
    Find the tension T in each cable and the magnitude and direction of the force exerted on the strut by the pivot.
    I know how to find T. The only problem is i couldnt imagine the force exerted on the strut by the pivot. I dont even know what that means. Can someone explain it to me and help me solve this problem.

    I also noticed that i need to find the force on the pivot for some other problems. Is there any easy ways to find the force? at least, how to picture it. Once i know where it is, i think i could solve it. untitled-1.jpg
    Last edited: Nov 25, 2009
  2. jcsd
  3. Nov 24, 2009 #2
  4. Nov 24, 2009 #3
    Draw a free body diagram for each joint.
  5. Nov 24, 2009 #4
    I know how to do it, the only problem is i dont know how to determine the net force on the pivot.
    thats it. thats my only problem. I know how to solve T, but I dont know how to solve the net force exerted on the strut by the pivot
  6. Nov 25, 2009 #5
    OK. The diagram does not show a pivot where the strut meets the wall, but I assume that is supposed to be a pivot? In that case the strut is always in either pure tension or compression since you cannot transmit torque at either end. So, the force exerted on/by the strut at the upper right (where the two cables are) must be balanced by a force at the pivot. Do you have that force at the upper right?
  7. Nov 25, 2009 #6
    I need this force exerted by the wall.

  8. Nov 25, 2009 #7
    Yes, I understand. Do you have the FBD solved at the upper right?
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