A physics professor demonstrates the Doppler effect by tying a 600 Hz sound generator to a 1.0-m-long rope and whirling it around her heard

Question

A physics professor demonstrates the Doppler effect by tying a 600 Hz sound generator to a 1.0-m-long rope and whirling it around her heard in a horizontal circle at 100 rpm. What are the highest and lowest frequencies heard by a student in the classroom? Assume the room temperature is 20∘C.

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Edana Edana 5 years 2021-08-31T06:12:21+00:00 1 Answers 27 views 0

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  1. vankhanh
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    2021-08-31T06:13:34+00:00
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    Answer:

    Therefore the the highest frequency is 620Hz and lowest frequency is 580Hz

    Explanation:

    Given data

    Source Frequency fs=600Hz

    Length r=1.0m

    RPM=100 rpm

    The speed of the generator is calculated as:

    v_{s}=rw\\v_{s}=r(2\pi f)

    Substitute the given values

    v_{s}=(1.0m)2\pi (\frac{100}{60}rev/s )\\v_{s}=10.47m/s

    For approaching generator the frequency is calculated as:

    f_{+}=\frac{f_{s}}{1-\frac{v_{s}}{v} }\\f_{+}=\frac{600Hz}{1-\frac{10.47m/s}{343m/s} } \\f_{+}=620Hz

    On the other hand,for the receding generator,Doppler’s effect is expressed as:

     f_{-}=\frac{f_{s}}{1+\frac{v_{s}}{v} }\\f_{-}=\frac{600Hz}{1+\frac{10.47m/s}{343m/s} } \\f_{-}=580Hz

    Therefore the the highest frequency is 620Hz and lowest frequency is 580Hz

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