A bat is flitting about in a cave, navigating via ultrasonic bleeps. Assume that the sound emission frequency of the bat is 38.9 kHz. During

Question

A bat is flitting about in a cave, navigating via ultrasonic bleeps. Assume that the sound emission frequency of the bat is 38.9 kHz. During one fast swoop directly toward a flat wall surface, the bat is moving at 0.015 times the speed of sound in air. What frequency does the bat hear reflected off the wall?

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Thái Dương 3 years 2021-08-09T17:47:16+00:00 1 Answers 11 views 0

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  1. thienthi
    0
    2021-08-09T17:48:47+00:00
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    Answer:

    40085 Hz

    Explanation:

    We are given; Sound frequency emmision of bat;f = 38.9 kHz = 38900 Hz

    Bat is moving at 0.015 times the speed of sound in air.

    Speed of sound in air = 343 m/s

    The formula for waves reflected off the wall is calculated from Doppler equation as:

    f’ = f(v + v_d)/(v – v_s)

    Where;

    f is the frequency = 38900 Hz

    f’ is the detected frequency,

    v_d is the velocity of the detector = 0.015 × 343 = 5.145

    v_s is the velocity of the source = 0.015 × 343 = 5.145 m/s

    v is the velocity of the sound = 343 m/s

    Thus;

    f’ = 38900(343 + 5.145)/(343 – 5.145)

    f’ ≈ 40085 Hz

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