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I need help with some Equilibrium problems

  1. Nov 12, 2006 #1
    #2: A traffic light hangs from a structure as shown in Fig. 9-60. The uniform aluminum pole AB is 7.5 m long and has a mass of 8.0 kg. The mass of the traffic light is 12.0 kg. Determine the tension in the horizontal massless cable CD, and the vertical and horizontal components of the force exerted by the pivot A on the aluminum pole.
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    Can I just get help on this one? I figured out the rest.
     
    Last edited: Nov 13, 2006
  2. jcsd
  3. Nov 13, 2006 #2
    Anyone want to help?
     
  4. Nov 13, 2006 #3

    Hootenanny

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    One is expected to show ones efforts. Let's start with what you know...
     
  5. Nov 13, 2006 #4
    Well, I know that the weight of the pole is 78.4 N and the light's weight is 117.6N, and that the light makes a 53degree angle with the pole, and since the sum of torques has to be 0, I need to seperate the weights into their x and y components... the problem with that was I got stuck when I realized that I didn't know what the x value of the point Ft acts on was... Is it safe to assume that since sum of torques is 0, that Ft and the force exerted by A are aqual but opposite in direction?
     
  6. Nov 13, 2006 #5

    Hootenanny

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    I would recommend taking moments about point A, then you don't need to worry about any forces acting through A. :wink:
     
  7. Nov 13, 2006 #6
    "taking moments"? do you mean setting A as the origin for torque?
     
  8. Nov 13, 2006 #7

    Hootenanny

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    Yes, apologies; the jargon can vary from course to course.
     
  9. Nov 13, 2006 #8
    ok, thanks!
     
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