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Homework Help: Beat frequency in Ultrasound

  1. May 12, 2007 #1
    1. The problem statement, all variables and given/known data

    Ultrasound reflected from an oncoming bloodstream that is moving at 38 cm/s is mixed with the original frequency of 1.3 MHz to produce beats. What is the beat frequency? (Velocity of sound in blood = 1540 m/s.)

    2. Relevant equations

    Fb- (F2-f1)

    3. The attempt at a solution

    idk where to start...
  2. jcsd
  3. May 12, 2007 #2


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    Homework Helper

    you are given the original freq... need to work out the reflected freq first... which would be doppler shifted due to moving source... I think you have got your two relevant equations written down.
  4. May 12, 2007 #3
    so Fobserver is 1300000Hz, Vsource is .38m/s, and Vobserver is 1540 m/s?

    so i would do 1300000=Fsource (345 + 1540/345-.38)

    take this # and subtrack by 1300000?
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