A car sounding a horn of frequency 1000 Hz passes a stationary observer. The ratio of frequen'ies of the horn noted by the observer before and after passing of the car is $11: 9$. The speed of car is (speed of sound $v=340 \mathrm{~ms}^{-1}$ )
- A$34 \mathrm{~ms}^{-1}$
- B$17 \mathrm{~ms}^{-1}$
- C$170 \mathrm{~ms}^{-1}$
- D$340 \mathrm{~ms}^{-1}$
✓ Correct answer: A
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