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Two cars honking at the same frequency of 800 Hz are moving toward a pedestrian standing at the curb. One car is moving with speed 25 m/s, a
Question
Two cars honking at the same frequency of 800 Hz are moving toward a pedestrian standing at the curb. One car is moving with speed 25 m/s, and the second car is moving at 21 m/s. What is the frequency of the beats heard by the pedestrian? Take the speed of sound as 343 m/s.
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1 year
2021-08-15T03:44:07+00:00
2021-08-15T03:44:07+00:00 1 Answers
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Answer:
The frequency of the beats heard by the pedestrian is 9.33 Hz
Explanation:
Frequency of the two cars, F = 800 Hz
speed of sound in air, V = 343 m/s
The sound wave length, λ = ?
λ = V / F
λ = 343 / 800
λ = 0.42875 m
The frequency of the car moving at 25 m/s heard by the pedestrian
f₁ = v₁ / λ
f₁ = 25 / 0.42875
f₁ = 58.31 Hz
The frequency of the car moving at 21 m/s heard by the pedestrian
f₂ = v₂ / λ
f₂ = 21 / 0.42875
f₂ = 48.98 Hz
The beat frequency = f₁ – f₂
= 58.31 – 48.98
= 9.33 Hz
Therefore, the frequency of the beats heard by the pedestrian is 9.33 Hz