question_answer

A whistler of frequency 540 Hz rotates in a circle of radius 2m at an angular speed of\[15\text{ }rad/sec\]. What is the lowest and highest frequency heard by listener? (take \[{{V}_{sound}}\,\,=\,\,330\text{ }m/sec\])    

A) 540,330                        

B) 495,540

C) 495,594            

D) same always

Correct Answer: C

Solution :

\[V\,\,=\,\,r\omega \] \[V=2\times 15\,\,=\,\,30\,m/sec\] At D \[{{f}_{D}}=\frac{330}{330-30}\,\,=\,\,594\,\,Hz\] \[{{f}_{B}}=\frac{330}{330+30}\,\,=\,\,495\,\,Hz\]