Bystander Beat Frequency Two cars have identical horns, each emitting a frequenc

Question

Bystander Beat Frequency

Two cars have identical horns, each emitting a frequency fs. One of the cars is moving toward a bystander waiting at a corner, and the other is parked. The two horns sound simultaneously.


(a) From the moving horn, does the bystander hear a frequency that is greater than, less than, or equal to fs? greater than fs less than fs equal to fs


(b) From the stationary horn, does the bystander hear a frequency that is greater than, less than, or equal to fs? less than fs greater than fs equal to fs


(c) Does the bystander hear a beat frequency from the combined sound of the two horns? No, because the two frequencies heard by the bystander are different. Yes, because the two frequencies heard by the bystander are different. No, because the two frequencies heard by the bystander are the same. Yes, because the two frequencies heard by the bystander are the same.



The frequency that the horns emit is fs = 220 Hz. The speed of the moving car is 8.0 m/s, and the speed of sound is 343 m/s.


(d) What is the algebraic expression for the frequency fo heard by the observer from the moving horn? Express your answer in terms of the frequency fs emitted by the moving horn, the speed vs of the moving horn, and the speed v of sound.
fo =


(e) What is the frequency fo heard by the observer from the moving horn?

Number Unit fo = ---Select---Pam/sHzNJkg

(f) What is the beat frequency heard by the bystander?

Number Unit Beat frequency = ---Select---NkgJm/sHzPa

Explanation / Answer

small typo for part f

a) since moving towards greater than fs

b)equal to fs

c) yes since the frequencies are different

d)

f = v/(vs-v) fs

e) f = 343/(343-8)*220=225.25 Hz

f) fbeat = f - fs = 5.25 Hz

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