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Homework Help: Forces quiz help

  1. Oct 17, 2007 #1
    forces quiz help plz!!!

    1. The problem statement, all variables and given/known data
    the distance between two telephone poles is 50.0m when a 1.00kg bird lands on the telpephon wire midway between the poles, the wire sags .200 m. draw a FBD of the bird. How much tension does the bird produce in the wire? ignore the weight of the wire.

    2. Relevant equations

    3. The attempt at a solution
    I got the free body diagram. but they dont give you any angles, so when i im not sure how to proceed?
  2. jcsd
  3. Oct 17, 2007 #2
    Well, you need to assume the poles are of the same height. Now the bird is mid-way between the poles. This is important. With that information, what can you say about the tension in the wires that go from the bird to the poles? In what ratio are they? Then you can draw your FBD, and solve it how you like, by resolving the forces, or with a triangle of forces.
  4. Oct 17, 2007 #3
    the tensions would be equal, so then i set up the triangles, but i cant use sin or cos cuz i dont have an angle
  5. Oct 17, 2007 #4
    You do have an angle. The distance between the poles is 50m and the line sags 0.2m, you can get an angle from that information.
  6. Oct 17, 2007 #5
    o0o right....i could do inverse tan and that would give me the angle
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