Question bank/JEE Main/Physics
JEE MainPhysics
A car is initially at rest, 330 m away from a stationary
observer. It begins to move towards the observer with an acceleration of
[IMAGE], sounding its horn continuously. 20 second
later, the driver stops sound the horn. The velocity of sound in air is
330 m/s. The observer will hear the sound of the horn for a duration of
[IMAGE] sec. Find n.
Show answer and solution
[IMAGE] In 20 seconds, distance travelled by the Source is:
[IMAGE] Let, t = 0 be the starting time.
The sound wave started at t = 0 from reaches the observer at
'B' after [IMAGE] ie. observer started hearing the
sound at t = 1 sec. At t = 20 sec. the source reaches at 220 m
The last sound wave starting from reaches Hence, the observer do not hear the sound for whole 20 sec.
but for: [IMAGE] TOPIC: Sound wave
SUB TOPIC: Doppler effect
LEVEL: Moderate
[IMAGE] Let, t = 0 be the starting time.
The sound wave started at t = 0 from reaches the observer at
'B' after [IMAGE] ie. observer started hearing the
sound at t = 1 sec. At t = 20 sec. the source reaches at 220 m
The last sound wave starting from reaches Hence, the observer do not hear the sound for whole 20 sec.
but for: [IMAGE] TOPIC: Sound wave
SUB TOPIC: Doppler effect
LEVEL: Moderate
Source: Grass-G / Ph-28 Physics paper FST 16 Jan.docx
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