question_answer 27)

A bat is flitting about in a cave, navigating via ultrasonic beeps. Assume that the sound emission frequency of the bat is 40 kHz. During one fast swoop directly toward a flat wall surface, the bat is moving at 0.03 times the speed of sound in air. What frequency does the bat hear reflected off the wall?  

Answer:

Here, the frequency of sound emitted by the bat, v = 40 kHz.                                      Velocity of bat,  where is velocity of sound.                                        Apparent frequency of sound striking the wall       This frequency is reflected by the wall and is received by the bat moving towards the wall; So =0.03