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Homework Help: Mathmatical model of a pendulum

  1. May 8, 2017 #1


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    1. The problem statement, all variables and given/known data
    Suppose the pendulum string is attached to a point on the ceiling 30 cm from the wall. The weight is moved away from its rest position and released at time t=0. At time t=1.4 sec, it reaches its maximum distance from the wall, 37.4 cm away, and then swings back toward the wall again. At times 2.8 sec, the weight reaches a minimum distance of 23.2 cm form the wall, and then swings away again.
    Assuming that the amplitude of the pendulum's swing decreases exponentially with time, find an eqaution expressing the amplitude A in terms of time t.

    2. Relevant equations
    A(t)=A e^-kt

    3. The attempt at a solution
    I tried A(t)= A e^-kt , A= (37.4-23.2)/2=7.1 Don't know what to do next?
  2. jcsd
  3. May 8, 2017 #2

    Ray Vickson

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    Your function does not allow the pendulum bob to oscillate (i.e., swing back and forth).
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