At rest, a car's horn sounds the note A (440 Hz). The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 415 Hz. (a) Is the cyclist ahead of or behind the car? (b) What is the speed of the car?

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Physics

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6 November, 11:08

At rest, a car's horn sounds the note A (440 Hz). The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 415 Hz. (a) Is the cyclist ahead of or behind the car? (b) What is the speed of the car?

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Quinn Horn · Answer 1

(a) : The cyclist is behind the car.

(b) : The speed of the car are Vf = 31.97 m/s.

Explanation:

f = 440 Hz

f' = 415 Hz

Vo = 1/3 Vf

Vf=?

V = 343.2 m/s

f' = f * ((V - (-Vo) / (V - (-Vf))

clearing Vf:

Vf = 31.97 m/s

Vo = 10.65 m/s