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Homework Help: Travelling waves - help with formula

  1. Feb 9, 2014 #1
    1. The problem statement, all variables and given/known data
    A wave has the mathmatical form [itex]y(x,t)=2sin(6t-0.5x)[/itex]

    1. What is the waves frequency, wavelength and velocity

    2.Write an expression for the displacement of the wave as a function of time at a point 2m from the beginningof the wave.

    2. Relevant equations
    k=2\pi \lambda \\
    f=\frac{\omega}{2\pi} \\
    v=\lambda f

    3. The attempt at a solution

    For question 1 I took 6 from the wave equation to be the angular velocity and k to be 0.5 so i did..

    f=\frac{6}{2\pi}=0.95Hz \\
    \lambda=\frac{2\pi}{0.5}=4\pi metres \\
    v=\lambda f = 4\pi (0.95)=11.94 m/s

    For question 2 I am not too sure what the question is asking, if it is 2m from the start do I just plug 2 in for x in the wave equation given? to get [itex]2sin(6t-1)[/itex]?

    Any help appreciated, thanks :)
    Last edited: Feb 9, 2014
  2. jcsd
  3. Feb 9, 2014 #2


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    2017 Award

    You work looks good to me. I agree that the second question isn't worded very well. The phrase "from the beginning of the wave" is a little odd. But it seems reasonable to me to assume they mean from x = 0, in which case your expression is correct.
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