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Homework Help: SONAR and reflection head on!

  1. Nov 29, 2006 #1
    Two submarines are underwater and approaching each other head-on. Sub A has a speed of 12 m/s and sub B has a speed of 17 m/s. Sub A sends out a 1520 Hz sonar wave that travels at a speed of 1522 m/s.

    ... I already solved for this question ...

    ... What is the frequency of the sound detected by sub B (to the nearest Hz)? ...

    ... I used the Doppler equation and I got 1549 Hz as an answer, which is correct.

    ... My next question is ...

    ... Part of the sonar wave is reflected from B and returns to A. What frequency does A detect for this reflected wave (to the nearest Hz)?

    ... do I use the Doppler equation again ... or is there a reflection equation or concept that I missed out on?
  2. jcsd
  3. Nov 29, 2006 #2


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    Homework Helper

    Yes, you use it again, but perhaps not exactly the same way. Whatever the frequency of the reflected sound sub A is moving when it receives it.
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