MHTCET 2016 Physics Solved Paper

(b) We have given

f1

f2

= 2
f1 = apparent frequency heard by the listener when velocity v1 is towards the observer.
f2 = apparent frequency heard by the listener when velocity v1 is away from the observer.
Now, file apparentfrequency of sound heard by the listener when observer is moving towards the source is given by
f1=(

V

V−V1

)f0 ....(i)
Similarly when observer is moving away from the source, apparent frequency heard by the listener is given by
f2=(

V

V+V1

)f0......(ii)
From eqs. (i) and (ii), we get

f1

f2

=

( V V−V1 )f0

( V V+V1 )f0

=

V+V1

V−V1

⇒

V+V1

V−V1

=2 ⇒ 2V−2V1=V+V1
⇒ V = 3V1⇒

V

V1

= 3