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Homework Help: Transverse Wave Problem

  1. Apr 6, 2010 #1
    1. The problem statement, all variables and given/known data

    A transverse wave on a rope is given by the following equation.
    y(x, t) = ( 0.710 cm ) cos pi [(0.400 cm^-1)x + (500 s^-1)t]

    From this, find the amplitude, period, frequency, wavelength and the speed of propogation.

    2. Relevant equations

    Well, I know that v=f*lambda. I also know the general equation for sinusodal models in the -x direction:

    y(x,t)= A*cos2pi[(x/lamda)+(t/period)]

    (I choose to use this particular equation because it ties in with the one given to me)

    3. The attempt at a solution

    This problem is driving me nuts. I should be able to just take out the units that it aligns with and get that for the answer, right? I took out the 0.71, so I found the amplitude. I found the frequency by dividing 500 by 2. I found the period by dividing 1/250. But I can't for the life of me find the wavelength or the speed of propogation, can anyone please help? Thanks very much!
    Last edited: Apr 6, 2010
  2. jcsd
  3. Apr 6, 2010 #2
    Can anyone please help? I'm so lost.
  4. Apr 17, 2010 #3
    The form y(x,t) = A cos (kx-wt) is more appropriate here...k is equal to 2PI/lambda and
    w = vk. So your amplitude is given, period and frequency can be derived from the value given for angular velocity (w), wavelength derives from the value for k...and your speed of propagation is found using angular velocity (w) and wave number (k). Good Luck!
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