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Pendulum Problem and steiner' law

  1. Apr 8, 2009 #1
    1. The problem statement, all variables and given/known data
    A uniform circular disk whose radius R is 14.3 cm is suspended as a physical pendulum from a point on its rim. (a) What is its period? (b) At what radial distance r < R is there a pivot point that gives the same period? (give answer in cm)

    2. Relevant equations
    T= 2pi radical ( I / mgh )

    3. The attempt at a solution
    Okay, I already found part A using T= 2pi radical ( I / mgh )
    Any help would be greatly appreciated =]

    Part A: 0.849 s <-- It's correct.
    I'm just stuck on Part B.
  2. jcsd
  3. Apr 8, 2009 #2
    Use steiner' law to express the I through a parallel axis..
  4. Apr 8, 2009 #3


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    Homework Helper

    You can find the radial distance by equating period of the disk to that of a simple pendulum.
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