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Homework Help: Pendulum with a twist

  1. Apr 3, 2007 #1
    1. The problem statement, all variables and given/known data
    A pendulum 2 meters long with a mass of 1kg is mounted on a circular platform on the earth's surface that's spinning at constant angular velocity of .12 rads/sec. The pendulum is mounted on a pole that's perpendicular to the platform at a distance of 5 meters from the center of rotation.

    If it's displaced for its equilibrium position, what will be the period of the pendulum?

    P.S. My physics teacher said that the diagrams below explains what's happening:

    http://answerboard.cramster.com/answer-board/image/43e827330329f2500585d3862fc2f7af.jpg [Broken]

    http://answerboard.cramster.com/answer-board/image/2bf7be21984fbe2a0b76f2f86b744710.jpg [Broken]

    Now, he mentioned how we must get the force from the equation F=mv2/r and then get the acceleration from a=F/m, but first I need to get r and I have no clue how to do that since theta isn't given. Then I have to replace the acceleration I get for g in the period equation.
    Please help!!!

    2. Relevant equations

    3. The attempt at a solution

    No clue!!!!!!!!?!?!?!
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Apr 3, 2007 #2


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    Gold Member

    Do you know how to work out the period of a pendulum that's not on a turntable ?

    One of the numbers in the equation is the 'return force' on the bob. You'll need to replace that with a different force for the rotating pendulum.
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