6. A police car is approaching towards a place with speed 27 m/s and emits sound of frequency 512 Hz. If a thief is running away with speed 13 m/s, find frequency heard by him. (speed of sound 320 m/s)
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Pls answer my question(Physics)
Answers
Answered by
0
Answer:
Let f
h
′
and f
s
′
be the frequencies of the horn and siren respectively heard by the motorcycle man.
Given: f
h
=176Hzf
s
=165Hzv
policecar
=22m/s
Doppler effect for police car and motorcycle:
f
h
′
=f
h
[
v
sound
−v
policecar
v
sound
−v
man
] =176[
340−22
340−v
] ............(1)
Doppler effect for siren and motorcycle:
f
s
′
=f
s
[
v
sound
v
sound
+v
man
] =165[
340
340+v
] ............(2)
As the motorcycle man doesn't hear any beat, i.e f
h
′
=f
s
′
176[
318
340−v
]=165[
340
340+v
]
⟹v=22.3m/s≈22m/s
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