qz10sol_6839sp10

# qz10sol_6839sp10 - D is negative if the detector is...

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TA: Tomoyuki Nakayama Tuesday, April 19 th , 2010 PHY 2048: Physic 1, Discussion Section 6839 Quiz 10 (Homework Set # 13) Name: UFID: Formula sheets are not allowed. Calculators are allowed. Do not store equations in your calculator. You need to show all of your work for full credit. ________________________________________________________________________________ A sound source A and a reflecting surface B move directly away from each other. Relative to the air, the speed of source A is 30.0 m/s, the speed of surface B is 70.0 m/s, and the speed of sound is 330 m/s. The source emits waves at frequency 800 Hz as measured in the source frame. a) In the reflector frame, what is the frequency of the arriving sound waves? The Doppler effect equation is f D = f S (v + v D )/(v - v S ), where v
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Unformatted text preview: D is negative if the detector is receding from the source and v S is negative if the source is receding from the detector. Since the source (source A) and the detector (reflector B) are moving away from each other, we get f B = f A (v + (-v B ))/(v – (-v A ))= 578 Hz b) In the source frame, what is the frequency of the sound waves reflected back the source? Now reflector B acts as a source, emitting the sound at the frequency obtained in part a). The detector is source A. Since they’re moving away from each other, we have f A ’ = f B (v + (-v A ))/(v – (-v B ))= 434 Hz c) In the source frame, what is the wavelength of the sound waves reflected back to the source? One of the expressions for wave speed yields v = fλ ⇒ λ = v / f A ’ = 0.760 m...
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