waec model questions vol1 2019 physics
Objective • Question 3
Question 3
WAEC_MODEL_QUESTIONS_VOL1
•
2019
A police siren emits a sound of frequency 800 Hz. The siren is mounted on a car moving directly towards a stationary observer. The observer also hears a stationary source that emits a sound of frequency 840 Hz. The observer perceives a beat frequency of 40 Hz. Assuming the speed of sound in air is 340 m s⁻¹, determine the speed of the car (in metres per second, to the nearest whole number).
Answer Options
A.
28 m/s
B.
40 m/s
C.
35 m/s
Correct Answer
D.
31 m/s
Correct Answer
D
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