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Manipal MET2017PhysicsWaves and Sound

A stationary police car sounds a siren with a frequency of 990 Hz . If the speed of sound is 330 ~m / s , an observer, driving towards the car with a speed of 33 ~m / s , will hear a frequency of

Options

  1. A891 Hz
  2. B900 Hz
  3. C1089 Hz
  4. D1100 Hz

Correct answer

C. 1089 Hz

Step-by-step solution

From Doppler's effect the perceived frequency f^ is given by f^ =f ( v+v₀ v ) Given, f=990 ~Hz , v=300 ~m / s , v₀=33 ~m / s aligned f^ & =990 ( 330+33 330 ) & =990 363 330 =1089 ~Hz aligned

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