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Sound from a racecar

  1. Nov 29, 2006 #1
    The pitch of the sound from a racecar engine drops the musical interval of a fourth when it passes the spectators. This means the frequency of the sound after passing is 0.75 times what it was before. How fast is the racecar moving?

    a. 68 m/s
    b. 49 m/s
    c. 61 m/s
    d. 72 m/s
  2. jcsd
  3. Nov 29, 2006 #2
    I cannot figure out how to work this problem out, any help would be great. Thanks in advance.
  4. Nov 30, 2006 #3
    Think of what formulae that comes to your mind when you do this question.
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