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Homework Help: Oscillatory Motion Problem

  1. Sep 7, 2014 #1
    1. The problem statement, all variables and given/known data

    The position of a particle is given in cm by x = 6*cos(3πt), where t is in seconds.

    What is the first time that the particle is at x = 0 and moving in the +x direction?

    2. Relevant equations

    3. The attempt at a solution

    I set x=0, and divided 0 by 6, resulting in 0. From there, I took the inverse cosine of each side, leaving me with the equation (π/2)=3πt. Then I divided (π/2) by 3π, and was left with a t value of .13351 seconds. The problem is that when I submit that answer, it is incorrect.
  2. jcsd
  3. Sep 7, 2014 #2


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    Homework Helper

    You ignored that the particle moves in the +x direction: the velocity is positive.

    How do you get the velocity of the particle at time t?

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