Question

A bat is flitting about in a cave, navigating via ultrasonic bleeps. Assume that the sound emission frequency of the bat is 37.5 kHz. During one fast swoop directly toward a flat wall surface, the bat is moving at 0.021 times the speed of sound in air. What frequency does the bat hear reflected off the wall?

Answer 1

Answer:

39.11 Hz

Explanation:

Data provided in the question:

Frequency of sound emission, $f_0$ = 37.5 kHz = 37500 Hz

Speed of bat, $v_{bat}$ = 0.021 times the speed of sound

Now,

Frequency heard by bat = $f_0\times(\frac{v+v_{bat}}{v-v_{bat}})$

Therefore,

The Frequency heard by bat will be = $37500\times(\frac{343+0.021\times343}{343-0.021\times343})$

or

Frequency heard by bat will be= $37500\times\frac{350.203}{335.797}$

or

Frequency heard by bat will be = 39108.78 Hz = 39.11 Hz