A hawk flying at 38 m/s emits a cry whose frequency is 440 Hz. A wren is moving in the same direction as the hawk at 17 m/s. (Assume the speed of sound is 343 m/s.) (a) What frequency does the wren hear (in Hz) as the hawk approaches the wren? Hz (b) What frequency does the wren hear (in Hz) after the hawk passes the wren?

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DeniceSandidge DeniceSandidge · Answer 1 · 2019-09-15T11:17:01+02:00

Answer:

frequency wren hear when approaches is 470.29 Hz

frequency wren hear after hawk pass is 415.75 Hz

Explanation:

given data

hawk velocity Vs= 38 m/s

frequency f = 440 Hz

wren velocity Vo= 17 m/s

speed of sound s = 343 m/s

to find out

What frequency wren hear and What frequency wren hear after hawk pass

solution

we apply here frequency formula that is

[tex]f1=f ( \frac{s+V_o}{s+V_s} )[/tex] .........1

here f1 is frequency hear by observer

put here all value as Vo and Vs negative because it approaches

[tex]f1=f ( \frac{s-V_o}{s-V_s} )[/tex]

[tex]f1=440 ( \frac{343-17}{343-38} )[/tex]

f1 = 470.29 Hz

so frequency wren hear when approaches is 470.29 Hz

and

after passing from equation 1 we take both Vo and Vs as positive

[tex]f1=f ( \frac{s+V_o}{s+V_s} )[/tex]

[tex]f1=440 ( \frac{343+17}{343+38} )[/tex]

f1 = 415.75 Hz

so frequency wren hear after hawk pass is 415.75 Hz