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Homework Help: Speed of a moving observer toward stationary source (sound frequency)

  1. Apr 29, 2010 #1
    1. The problem statement, all variables and given/known data

    A stationary whistle emits a sound of 190 Hz. If a car hears the whistle with a frequency of 198 Hz, how fast was it moving (in m/s)? Use 340 m/s for the sound velocity

    2. Relevant equations

    f'=(1+Vo/V)f ======>>>> equation for the observer moving toward stationary source.

    3. The attempt at a solution

    f'=(1+Vo/V)f

    198=(1+Vo/340)190

    please help! what am i doing wrong?
     
  2. jcsd
  3. Apr 29, 2010 #2
    What did you get for your answer?
     
  4. Apr 29, 2010 #3
    i got 353.3157
     
  5. Apr 29, 2010 #4
    Well, then you made a mistake in your math. I believe your equation is right, but you seem to be messing up when solving the algebra. Your velocity should not be that fast.
     
  6. Apr 29, 2010 #5
    ok i believe i did the 198/190 times 340 -1 is that right?
     
  7. Apr 29, 2010 #6

    vela

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    No, it's not.
     
  8. Apr 29, 2010 #7
    ok i got a different answer now 14.3157 is this one right?
     
  9. Apr 29, 2010 #8
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