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Homework Help: Acceleration in Harmonic Motion

  1. Jun 3, 2017 #1
    A pendulum that has a period of 3.00000s and that is located where the accleration due to gravity is 9.79 m/s^2 is moved to a location where the acceleration due to gravity is 9.82 m/s^2. What is its new period, in s?

    Equation for Harmonic motion: x = A sin (2pi * f * t)

    Acceleration for Harmonic motion: a = -4pi^2 A f^2 sin(2pi f t)

    f = 1/t = 1/3

    Let A = 4 for both problems.
    9.79 = 16/9 * pi^2 * sin (2pi/3 t)

    Solving for t,
    sin(2pi/3 * t) = 0.55796309317
    2pi/3 * t = 0.5919292673 (radians)
    t = 0.282654065 seconds

    9.82 = 16 * pi^2 * f^2 sin(2pi * 0.282654 * f)
    f^2 sin(2pi * 0.282654 * f) = 0.06218587646

    Now I get a lot of answers for f.

    Not sure which one is the answer.

    Thank you!
  2. jcsd
  3. Jun 3, 2017 #2


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    Hello ciao_potter . Welcome to PF !

    You are not to use the acceleration resulting from harmonic motion.
    The pendulum is not likely to have an acceleration of g .

    What is the formula for the period of simple pendulum?
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