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Homework Help: Spring constants and such

  1. Apr 22, 2005 #1
    2 Questions, pretty stumped on both.
    A meter stick is hung at its center from a thin wire (see part (a) of the figure below).

    Meter stick is hanging from a string, and being "rotated clockwise.

    It is twisted and oscillates with a period of 6.18 s. The meter stick is sawed off to a length of 68.1 cm. This piece is again balanced at its center and set in oscillation (b). With what period does it oscillate?

    Not really even sure where to start on this one... still looking at it.

    Next:A 56.8 kg person jumps from a window to a fire net 21.8 m below, which stretches the net 1.25 m. Assume that the net behaves like a simple spring, and calculate how much it would stretch if the same person were lying in it.

    Tried mgh = .5kx^2, then used F/k=x, but this didn't work, any ideas?
  2. jcsd
  3. Apr 22, 2005 #2


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    We need a better idea what the first problem is. Does the thin wire have some length, and does it move in the problem? Is the point of contact bwteen the meter stick and the wire stationary?

    Your second problem sounds like you have the right idea. Did you include the stretch in your h?
  4. Apr 22, 2005 #3
    Good call on that second one, forgot to add h from stretch.

    On the first one. The wire is stationary, no length given. The meter stick is hung by the middle, and a force is applied to make it spin in a plane horizontal to the ground, at least that is my understanding of the problem.

    Any ideas?
  5. Apr 22, 2005 #4
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