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KCET2024PhysicsWaves and Sound

A motor-cyclist moving towards a huge cliff with a speed of 18 kmh ⁻¹ , blows a horn of source frequency 325 Hz . If the speed of the sound in air is 330 ~ms ⁻¹ , the number of beats heard by him is

Options

  1. A5
  2. B4
  3. C10
  4. D7

Correct answer

A. 5

Step-by-step solution

Speed of motor-cyclist, v_s=18 ~km / h =18 5 18 ~m / s =5 ~m / s Frequency of source, f=325 ~Hz Speed of sound, v=330 ~m / s Number of beats heard by motor-cyclist. f=f ( v_s v-v_s )=325 ( 5 330-5 )=5

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