Question

A 500 Hz whistle is moved toward a listener at a speed of 10 m/s. At the same time, the listener moves at a speed of 20 m/s in a direction away fromm the whistle. What is the apparent frequency heard by the listener? (the speed of sound is 340 m/s)

A) 473 hz
B) 376 hz
C) 485 hz
D) 533 hz
E) 547hz

Answer 1

Frequency will be 485 Hz

So option (c) will be the correct option

Step-by-step explanation:

We have given frequency f = 500 Hz

Velocity of observer
`v_o=20m/sec`

Velocity of source
`v_s=10m/sec`

When both observer and source are moving then frequency is given by

`f'=(v-v_o)/(v-v_s)* f` , here v is the velocity of sound

So
`f'=(340-20)/(340-10)* 500=485Hz`

So option (c) will be the correct option