Doppler effect for a source passing a stationary observer: frequencies while approaching and receding
This type of question, asked 5 times: 3 May 2023 S1, 4 May 2023 S2, 11 May 2024 S1, 11 Apr 2026 S2, 16 Apr 2026 S2. All 5 questions below, oldest first.
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Question 1
3 May 2023 S1
33The pitch of a whistle of an engine appears to drop by 30% of original value when it passes a stationary observer. If the speed of sound in air is , then the speed of engine in isTap an option to check your answer.
Question 2
4 May 2023 S2
43A train sounding a whistle of frequency 510 Hz approaches a station at 72 km/hr. The frequency of the note heard by an observer on the platform as the train (1) approaches the station and then (2) recedes the station are respectively (in hertz) (velocity of sound in air = 320 m/s)Tap an option to check your answer.
Question 3
11 May 2024 S1
26A car sounding a horn of frequency 1000 Hz passes a stationary observer. The ratio of frequencies of the horn noted by the observer before and after passing the car is . If the speed of sound is , the speed of the car isTap an option to check your answer.
Question 4
11 Apr 2026 S2
124A source of sound is moving towards a stationary observer with velocity '' and then moves away with velocity ''. Assume that medium through which the sound waves travel is at rest. If 'V' is the velocity of sound and 'n' is the frequency emitted by the source then the difference between the apparent frequencies heard by the observer isTap an option to check your answer.
Question 5
16 Apr 2026 S2
124A person observes two moving trains. 'A' reaching the station and 'B' leaving the station with equal speed of 30m/s. If both trains emit sounds with frequency 300 Hz, (speed of sound = 330 m/s) difference of frequencies heard by the person will beTap an option to check your answer.