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Homework Help: Torsional Pendulum, Logarithmic Decrement

  1. Jul 21, 2009 #1
    The amplitude of a torsional vibration decreases so that the amplitude on the 100th cycle is 13% of the the amplitude of the first cycle. Determine the level of damping in terms of the logarithmic decrement.

    Is this simply ln(100/13)= 2.04

    or ln(13/100)= -2.04?
     
  2. jcsd
  3. Jul 22, 2009 #2

    rl.bhat

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    Level of damping δ = 1/n*ln(xo/xn)
    where n is the number of cycles, xo is the initial amplitude and xn is the amplitude after n cycles.
     
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