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Homework Help: Graph of a sinusoidal wave at a fixed position

  1. Jul 4, 2009 #1
    1. The problem statement, all variables and given/known data

    A sound wave is described by D(y,t) = (0.02mm)sin[(8.96 rad/m)y + (3140 rad/s)t + pi/4 rad)], where y is in metres, and t is in seconds.

    Draw a displacement-versus-time graph D(y=1.00m,t) at y= 1.00 m from t= 0 s and t= 4 ms.

    2. Relevant equations

    D(y,t) = (0.02mm)sin[(8.96 rad/m)y + (3140 rad/s)t + pi/4 rad)]

    3. The attempt at a solution

    I tried doing the graph (see figure attached), but apparently it's wrong. By 'fixed' position, it means that I must plug in 1.00 m into y for the entire time interval (0 to 4ms), correct? If that's the case, then all the points on the graph should be right. Can someone explain what I'm doing incorrectly?

    Attached Files:

  2. jcsd
  3. Jul 4, 2009 #2
    Ah, my bad. I jumped the gun and skipped the points in between each tick.
  4. Dec 14, 2010 #3
    I got the same graph as you did. How did you figure out how to get the points in between the points you already have on your graph? Because when I plug in y=1 into the equation, I don't get the right answer.
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