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Torsional pendulum, logarithmic decrement

  1. Jul 21, 2009 #1
    1. The problem statement, all variables and given/known data

    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.

    2. Relevant equations

    3. The attempt at a solution

    Is this simply ln(100/13)= 2.04

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


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    It will be a positive number (use 100/13, not 13/100). However, you still need to account for the fact that it takes 100 cycles to reach 13%.
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