question_answer

A train is moving on a straight track with speed . It is blowing its whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound  ) close to                                                                                          [JEE MAIN 2015]

A)  18%                            

B)  24%         

C)  6%                              

D)  12%

Correct Answer: D

Solution :

[d]

Frequency increases while approacting and decreases while receding.