A source of sound of frequency 500 Hz is moving towards a stationary observer with velocity 30 m/s . The speed of sound is 330 m/s . The frequency heard by the observer will be :

Question

A source of sound of frequency 500 Hz is moving towards a stationary observer with velocity 30 m/s . The speed of sound is 330 m/s . The frequency heard by the observer will be : (A)  545 Hz  (B)  580 Hz  (C)  458.3 Hz  (D)  550 Hz

Tardigrade Admin · Accepted Answer

From Doppler's effect, the perceived frequency

(f^{'})

is given by

f^{'} = f \frac{v}{v - v _{s}}

where

v_{s}

is velocity of source,

v

the speed of sound and

f

the original frequency. Given,

f = 500 Hz, v_{s} = 30 m / s, v = 330 m / s

f^{'} = 500 \times \frac{330}{330 - 30}

f^{'} = 500 \times \frac{330}{300} = 550 Hz

Q. A source of sound of frequency $500 Hz$ is moving towards a stationary observer with velocity $30 m / s$ . The speed of sound is $330 m / s$ . The frequency heard by the observer will be :

$545 Hz$

$580 Hz$

$458.3 Hz$

$550 Hz$

Q. A source of sound of frequency 500Hz is moving towards a stationary observer with velocity 30m/s . The speed of sound is 330m/s . The frequency heard by the observer will be :

545Hz

580Hz

458.3Hz

550Hz

From Doppler's effect, the perceived frequency (f′) is given by f′=fv−vs​v​ where vs​ is velocity of source, v the speed of sound and f the original frequency. Given, f=500Hz,vs​=30m/s,v=330m/s f′=500×330−30330​ f′=500×300330​=550Hz

Q. A source of sound of frequency $500 Hz$ is moving towards a stationary observer with velocity $30 m / s$ . The speed of sound is $330 m / s$ . The frequency heard by the observer will be :

$545 Hz$

$580 Hz$

$458.3 Hz$

$550 Hz$