Question

As a bat flies toward a wall at a speed of 6.0 m/s, the bat emits an ultrasonic sound wave with frequency 30.0 kHz. What frequency does the bat hear in the reflected wave?

Answer 1

Answer:

$f_b = 29.98 Hz$

Explanation:

speed of bat = 6 m/s

sound wave frequency emitted by bat = 30.0 kHz

as we know,

speed of sound (c)= 343 m/s

$f_w = f(\dfrac{c+v_r}{c+v_s})$

$f_w = 30(\dfrac{343+0}{343+6})$

$f_w = 29.48 Hz$

now frequency received by bat is equal to  

$f_b = f(\dfrac{c+v_r}{c+v_s})$

$f_b = 29.48(\dfrac{343+6}{343+0})$

$f_b = 29.98 Hz$

hence the frequency hear by bat will be 29.98 Hz