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Homework Help: Simple (supposedly) pendulum with unknown length and kinetic energy

  1. Nov 30, 2004 #1
    Please help, if a 60 g bob at the end of a cord (unknown length) of negligable mass and the angle [tex]\Theta = (0.0800 radian) cos[(4.43 radian / s.) t + \phi][/tex] <---- Angle between cord and the vertical.

    What are
    a) the pendulum's length?

    b) it's maximum kinetic energy?

    Please help, the prof did not go over any of this type of problem.
  2. jcsd
  3. Nov 30, 2004 #2


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    The 4.3 rad/s is the angular frequency which is related to the length of the pendulum. Can you take it from there?
  4. Nov 30, 2004 #3
  5. Nov 30, 2004 #4
    Ok, I gto part a) but not part b). Please help :smile:

    a) 0.494 meters

    But how do I relate that to find the x_max?
  6. Nov 30, 2004 #5


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    The kinetic energy will be highest when speed is highest. At what point is the speed of the pendulum highest? (If by x_max, you mean the highest point the pendulum reaches, that is irrelevant.)
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