A) 385 Hz
B) 374 Hz
C) 394 Hz
D) 333 Hz
Correct Answer: B
Solution :
Velocity of source (whistle) is given by |
\[{{v}_{s}}=r\omega \] |
\[=(0.5\,m)\,(20\,rad/s)\] |
\[=10\,m/s\] |
The frequency of sound observed by the observer will be minimum when he is at point A. Thus, at this point minimum frequency of source as observed by observer is |
\[{{n}_{\min }}=\left( \frac{v}{v+{{v}_{s}}} \right)n\] |
\[{{n}_{\min }}=\frac{340}{340+10}\times 385=\frac{34}{35}\times 385\] |
\[=34\times 11=374\text{ }Hz\] |
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