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Homework Help: Find tension with two cables at different angles

  1. Oct 6, 2011 #1
    1. The problem statement, all variables and given/known data

    A weight of 5000 N is suspended by two cables. The object is at rest. The first cable is horizontal and the second makes an angle of 143 ° with the first cable. Find the tension of the first cable.


    2. Relevant equations
    Erm...I know it's something with sin or cosin.


    3. The attempt at a solution
    My teacher hasn't given us any equations that have to do with tension, so I am completely and utterly lost. Any help would be greatly appreciated!
    It's multiple choice and the possible answers are
    4000 N
    6640 N
    8310 N
    3340 N
     
  2. jcsd
  3. Oct 7, 2011 #2
    if the object is at rest, then accelersation is zero.
    if accelaration is zero, then the net force is zero.
     
  4. Oct 7, 2011 #3
    The tension is just the force exerted by the cables.

    Have you made a drawing and applied the three forces working?
     
  5. Oct 7, 2011 #4
    Indeed, there is some sin or cos involved. As mentioned above, the acceleration is zero. What does this imply about the vertical part of the tension?
     
  6. Oct 7, 2011 #5
    if you break the problem into a horizontal and a vertical part, the sum of forces should be 0 in each of these.

    in the horisontal, the force on cable 1 must be equal to the HORIZONTAL PART of the force of cable 2.

    In the vertical the VERTICAL PART of cable 2 must balance gravity.

    Agree?
     
    Last edited: Oct 7, 2011
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