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Homework Help: Frequency heard, need someone to check

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

    A train is traveling 30 m/s in still air. The frequency of the train whistle is f = 250 Hz. What frequency is head by a passenger on a train moving in the opposite direction at 18 m/s and approaching the first train? The velocity of sound in air is 344 m/s.

    2. Relevant equations

    F = [(1(+/-) (Velocity listener)/velocity sound) / (1(+/-) (Velocity source)/velocity sound)] *frequency

    3. The attempt at a solution

    Since the listener is moving towards the source and the source is moving towards the listener the forumula becomes

    F = [(1+(Velocity listener)/velocity sound) / (1 - (Velocity source)/velocity sound)] *frequency

    After plugging in the numbers i got 288Hz, is that correct?

    it makes sense because the listener would hear a higher frequency b/c the source is moving towards the listener

    thanks
     
  2. jcsd
  3. Mar 1, 2010 #2
    so, is it right?
     
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