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Homework Help: Pendulum beam Problem

  1. Mar 29, 2007 #1
    1. The problem statement, all variables and given/known data

    On the construction site for a new skyscraper, a uniform beam of steel is suspended from one end. If the beam swings back and forth with a period of 1.10 s, what is its length?

    2. Relevant equations

    T=2*pi*sqroor (L/g)

    3. The attempt at a solution



    This is wrong however and I don't understand why.
  2. jcsd
  3. Mar 29, 2007 #2


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    The period equation you have written is for a simple pendulum with a point mass at the end. You cannot use it for this case, since the mass is uniformly distributed along the beam. You must find or derive the correct formula for this case.
  4. Mar 29, 2007 #3
    This is the case of physical pendulum. The gravitational force acts at centre of mass and u can assume a point mass hanging there and then calculate.
  5. Mar 29, 2007 #4


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    no, you will need the moment of inertia of the steel rod as well
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