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Homework Help: Find the tension in the two wires

  1. Mar 19, 2007 #1
    1. The problem statement, all variables and given/known data
    Find the tension in the two wires supporting the 36 kg traffic light shown in Fig. 12-57. (Assume that 1 = 52° and 2 = 38°.)

    http://img15.imgspot.com/u/07/77/15/952alt.gif [Broken]

    2. Relevant equations
    -T1cos(52)+T2cos(38)=m*g
    T1sin(52)+T2sin(38)=0


    3. The attempt at a solution

    so I found T1=-T2sin(38)/sin(52)
    and plugged into the first equation and got
    [sin(38)*cos(52)/sin(52)+cos(38)]*T2=353.16
    and got T2 = 278N
    and T1=217N

    but when I put it into the webassign it is wrong...
    so what am I doing wrong?
     
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Mar 19, 2007 #2

    radou

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    Homework Helper

    It would be useful if you presented the figure somehow.

    You may want to check your trig, although I can't tell for sure.
     
  4. Mar 19, 2007 #3
    i think the sins and cosines are reversed. The vertical weight mg is opposed by the sines of the respective tensions.
     
  5. Mar 19, 2007 #4

    radou

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    Homework Helper

    denverdoc is right. Just "swap" m*g and 0.
     
  6. Mar 19, 2007 #5
    k thx a lot got it :)
     
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