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Homework Help: Find the weight.

  1. Oct 19, 2007 #1
    1. The problem statement, all variables and given/known data

    http://img150.imageshack.us/img150/1196/cci0710200700003dy8.jpg [Broken]
    The problem and diagram is given on the sheet.

    2. Relevant equations

    sigma Fx=0
    sigma Fy=0

    3. The attempt at a solution

    Starting freebody from point B
    T=tension, C=compression

    TBC = cos36.86deg = 3250N cos22.62deg
    TBC = 81.39N

    CBE = 81.39sin36.86deg + 3250sin22.62deg
    CBE = 1.3KN

    Now using Freebody at point C

    TDCcos45deg = 81.39cos36.86deg

    M=92.09sin45deg + 81.39sin36.86deg
    M=113.94N [FINAL ANSWER]

    am i doing this correctly? did i make a mistake anywhere? I have a test tomorrow i need to know if i am missing some fundamental knowledge.

    thank you for taking the time to help me.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Oct 19, 2007 #2


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    Homework Helper

    "TBC = cos36.86deg = 3250N cos22.62deg
    TBC = 81.39N"

    what happened here? TBCcos(36.86) = 3250cos(22.62) doesn't give TBC =81.39.

    other than this your work looks right to me.
    Last edited: Oct 19, 2007
  4. Oct 19, 2007 #3
    shoot! yes you are correct. I dont know how I miscalculated. It is a risk using shift-ANS function on my calculator, sharp el520. if you press = it will overwrite the memory for ANS and you can't go back.

    thank you. mistakes like this will ruin me on the test...if TBC is wrong then TDC will be wrong and so on.

    thanks again learningphysics!
  5. Oct 19, 2007 #4


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    Homework Helper

    Yeah, hopefully the professor will check your work and see what you were doing and only grade you down for that 1 mistake... this is the only mistake I saw in your work... I'd personally give you at least a 9/10... you're welcome. glad to help.
    Last edited: Oct 19, 2007
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