question_answer

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of\[19.4\,m{{s}^{-1}}\]at an angle of \[60{}^\circ \] with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air\[330\,m{{s}^{-1}}\]is

A)  97 Hz                          

B)  100 Hz

C)  103 Hz                        

D)  106 Hz

Correct Answer: C

Solution :

Apparent frequency \[f'=f\left( \frac{V-{{V}_{0}}}{V-{{V}_{s}}\cos 60} \right){{V}_{0}}=0\]