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NEET2006PhysicsWaves and SoundActual

A person is observing two trains one coming towards him and other leaving with the same velocity 4 ~m / s . If their whistling frequencies are 240 Hz each, then the number of beats per second heard by the person will be : (if velocity of sound is 320 ~m / s )

Options

  1. A3
  2. B6
  3. C9
  4. Dzero

Correct answer

B. 6

Step-by-step solution

Observed frequency of first train aligned n₁ & = v v-v_s n & = 320 320-4 240 & = 320 316 240 & =243 ~Hz . aligned Observed frequency of second train aligned n₂ & = v v+v_s n & = 320 320+4 240 & =237 ~Hz . aligned Number of beats =243-237=6

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