Question

80. A whistle producing sound waves of frequencies
9500 Hz and is approaching a stationary person
with speed vms. The velocity of sound in air
is 300 ms. If the person can hear frequencies
upto a maximum of 10,000 Hz. The maximum
value of v upto which he can hear the whistle
is
1) 30 ms-
3) 15/2 ms-
2) 15V2 ms-1
4) 15 ms-

Answer 1

Answer:

Using Doppler Effect,

ν'=(v-vl/v-vs) ν (vl-velocity of listener, vs-velocity of source)

10000=(300-0/300-vs)9500

10000/9500=300/300-vs

therefore, vs=15 m/s