# A siren emitting a sound of frequency 1000 H_(Z) moves away from you towards a cliff at a speed of 10 m//s . (a) What is the frequency of the soun

31 views
in Physics
closed
A siren emitting a sound of frequency 1000 H_(Z) moves away from you towards a cliff at a speed of 10 m//s .
(a) What is the frequency of the sounds, you hear coming directly from the sirven ?
(b) What is the frequency of sounds you hear reflected off the cliff . Speed of sound in air is 330 m//s ?

by (85.3k points)
selected

(a) sound heard directly
f _(1) = f _(0) ((nu)/(nu + nu_(S))) rArr nu_(S) = 10 m//s
:. f_(1) = ((330)/(330 +10)) xx1000
= 970.6 H_(Z)
(b) The frequency of the reflected sound is given by
f_(2) = f_(0) ((nu)/(nu - nu_(s)))
f_(2) = ((330)/(330 - 10))xx 1000
=1031.25 H_(Z)