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Homework Help: Simple Harmonic Motion - Alevel M3

  1. Mar 24, 2006 #1
    This is probably a really easy question. But alas the answer has eluded me thus far. Anyway, here is the question:-

    Points O, A and B lie in that order on a straight line. A particle P is moving on the line with S.H.M period of 4s, amplitude 0.5m and centre O. OA is 0.1m and OB is 0.3m. When t = 0, P passes through B travelling in the direction OB. Calculate the time when P passes A

    I tried using the following equation to find the first part of the motion, B to amplitude.

    X = a Sin(wt + 0.3)
    0.2 = 0.5 Sin(0.5Pi t + 0.3)

    and for the second part of the motion, amplitude to A:-

    0.4 = 0.5 Cos(wt)

    However i get nowhere near the correct answer of 1.46s when i add the two times together.

    Any help would be greatly appreciated,
  2. jcsd
  3. Mar 25, 2006 #2


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    Science Advisor
    Homework Helper

    Adjust the initial phase. The phase should be such that
    X(0)=0.3 m. You added 0.3 (m?) to the phase.
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