Two cars A and B are moving towards each other with samne speed 25 m/s. wind is blowing with speed 5 m/s in the direction of motion of car A. The car A blows horn of frequency 300 Hz and the sound is reflected from car B. the wavelength of te reflected sound received by the driver of car A is (velocity of sound in air =330m/s)

Options

A. `(25)/(36)m`
B. `(31)/(36)m`
C. `(35)/(36)m`
D. `(37)/(36)m`

Answer

B

Explanation

Frequency received by car B is `f_(1)=((v+w+u)/(v+w-u))f`
Now te car B will be treated as a source of frequency `f_(1)`
`therefore` wavelength of reflected sound received by the driver of car A is
`lamda'=((v-w-u))/(f_(1))=((v-w-u)(v+w-))/((v+w+u)f)`
`((330-5-25)(330+5-25))/((330+5+25)300)=(31)/(36)m`