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Homework Help: Dealing with wavelengths, frequencies and speed

  1. Nov 30, 2005 #1
    Ok, I am working with problems dealing with Speed=(lambda) (frequency).
    I have a question in determining whether Im solving these correctly. I sometimes get confused as what the wavelength is.

    1. A longitudinal wave with a frequency of 25.0Hz travels along a coil spring. If the distance between successive compressions is 0.500m, what is the speed of the wave.

    This is how i solved it. There is no need to show the steps becuase my question comes just when i frame the problem.

    speed is unknown
    wavelength is 0.500m

    My question is would the wavelength be twice as much as the distance between successive compressions, not 0.500m.

    2. Twenty five water waves pass your anchored boat in 1.0 min. If the separation between waves is 2.0m, what is the speed of the waves?

    This is how I would set up the problem

    t=1 min x 60 seconds = 60 seconds
    v = unknown
    wavelength is 2.0m

    Same question as the first, would the wavelength be 2.0 m or 4.0 m. Because wouldnt the seperation between the waves just be a loop.

  2. jcsd
  3. Nov 30, 2005 #2
    wavelength is the distance between 2 successive points on a wave.
    i think what is confusing you is the different types of waves. is that right?

    you are right about the first one. the distance between compressions is every half wavelength. do you know why?

    for the second one, a wavelength is the distance bewteen crests (actually any two successive points on a wave). do you know why?
  4. Nov 30, 2005 #3
    Thanks alot :wink:
  5. Nov 30, 2005 #4
    if you don't understand the difference you're going to have this problem again. and again. and probably some more after that.
  6. Dec 1, 2005 #5


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    You're saying that the wavelength of the compression wave is 1.0m? Not 0.5m?
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