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Homework Help: Waves- Group and Phase Velocities

  1. Nov 11, 2008 #1
    Waves-- Group and Phase Velocities

    1. The problem statement, all variables and given/known data
    distance= 3*10^20 m
    [tex]\omega[/tex]=(7.97*10^(-3)+ (KC)^2)^(1/2)
    [tex]\omega[/tex]= 1*10^9 Hz

    2. Relevant equations
    Phase Velocity= [tex]\omega[/tex]/k
    Group Velocity= d[tex]\omega[/tex]/dk

    3. The attempt at a solution

    I wrote the phase velocity as-- (7.97*10^(-3) +(KC)^2)^(1/2)/k is that correct?
    My group velocity is-- (the derivative of the above) -7.97*10^(-3)/(K^2[tex]\omega[/tex])
    is it a correct statement?
    Now, my biggest problem, I need to find the time it will take this wave to reach the Earth, any idea on how to do that?
  2. jcsd
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