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A bat moving at 10 m s − 1 towards a wall sends a sound signal of 8000 Hz towards it. On reflection, it hears a sound of frequency f . The value of f in Hz is close to ( speed of sound = 320   m s − 1 )

Options

  1. A8258
  2. B8424
  3. C8000
  4. D8516

Correct answer

D. 8516

Step-by-step solution

We can assume that reflected wave is due to image of B coming with same speed in opposite direction Observer f =   v + 10 v - 10   × f 0         =   320 + 10 320 - 10   × 8000         =   330 310   × 8000         =   33 31   × 8000       =   8516   Hz

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