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QAIPM-2012-Ph-1664: NEET 2012 Physics - Class 11 AIPM-2012-Ph-1664 Solution: A train moving at a speed of \(220\ {m s}^{-1}\) towards a…
A train moving at a speed of towards a stationary object emits a sound of frequency 1000 Hz. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (Speed of sound in air is ) 3500 Hz 4000 Hz 5000 Hz 3000 Hz
Multiple Choice Options
- A 3500 Hz
- B 4000 Hz
- C 5000 Hz
- D 3000 Hz
Step-by-Step Verified Solution
Here, Speed of the train, v T = 220 ms �1
Speed of sound in air, v = 330 ms �1
The frequency of the echo detected by the driver of the train is
_ _ = _ ( v + v T v _ v T ) = 1000 ( 330 + 220 330 _ 220 )
= 1000 _ 550 110 = 5000 H z