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COMEDK2023Morning ShiftPhysicsWaves and SoundActual

With what velocity should an observer approach a stationary sound source, so that the apparent frequency of sound should appear double the actual frequency?

Options

  1. A2 v
  2. Bv
  3. Cv / 2
  4. D3 v

Correct answer

B. v

Step-by-step solution

The apparent frequency f' heard by an observer moving towards a stationary source is given by the Doppler effect formula: f' = f ( v + v_o v ) where f is the actual frequency, v is the speed of sound, and v_o is the velocity of the observer. Given that the apparent frequency is double the actual frequency, we have f' = 2f . Substituting this into the formula: 2f = f ( v + v_o v ) Dividing both sides by f : 2 = v + v_o v 2v = v + v_o v_o = v Answer: v

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