An airplane traveling at half the speed of sound emits a sound of frequency 4.68 khz. (a) at what frequency does a stationary listener hear the sound as the plane approaches? khz (b) at what frequency does a stationary listener hear the sound after the plane passes? khz

(a) 9.36 kHz

(b) 3.12 kHz

Explanation:

(a)

V = speed of sound

= speed of airplane = (0.5) V

f = actual frequency of sound emitted by airplane = 4.68 kHz = 4680 Hz

f' = Frequency heard by the stationary listener

Using Doppler's effect

f' = 9360 Hz

f' = 9.36 kHz

(b)

V = speed of sound

= speed of airplane = (0.5) V

f = actual frequency of sound emitted by airplane = 4.68 kHz = 4680 Hz

f' = Frequency heard by the stationary listener

Using Doppler's effect

f' = 3120 Hz

f' = 3.12 kHz