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Homework Help: Waves Speed Problem

  1. Feb 24, 2007 #1
    A periodic longitudinal wave that has a frequency of 20.0 Hz travels along a coil spring. If the distance between successive compressions is 0.400 m, what is the speed of the wave?

    my answer:
    T=1/20=0.05 sec

    v=d/t= 0.400 meter/ 0.05 second= 8 m/s

    there is other question but i couldn't figure it out because i don't know how i can use pulses to get frequency or period

    the question is

    A wave generator produces 16.0 pulses in 4.00 s.
    a. What is its period?

    b. What is its frequency?

    can i know what pulse really mean, and if i am right by saying frequency will be 16/2=8 hertz
  2. jcsd
  3. Feb 24, 2007 #2


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    Homework Helper

    Your answer for for the second problem isn't quite correct. Why are you dividing by 2 and not 4?

    See here http://en.wikipedia.org/wiki/Pulse_wave for what a pulse wave looks like. The definition of frequency remains the same, it is still how many cycles you get per unit time.
  4. Feb 24, 2007 #3
    so that mean the first question is right!
  5. Feb 24, 2007 #4
    for pulses question it will be:
    period= 4/16=0.25 pulses

    frequency= 1/0.25= 4 hz

    am i right?
  6. Feb 24, 2007 #5


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    Homework Helper

    Period = 0.25 is correct, but "pulses" is not a unit. You mean "seconds" there, right? :smile:
    The frequency is correct.
  7. Feb 24, 2007 #6
    yep thank you
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