Question

A racing car moving towards a cliff, sounds its horn. The driver observes that the sound reflected from the cliff has a pitch one octave higher than the actual sound of the horn. If `v` is the velocity of sound, then the velocity of the car is
A. `(v)/(sqrt(2))`
B. `(v)/(2)`
C. `(v)/(3)`
D. `(v)/(4)`

Answer 1

Correct Answer - C
`f_(r)=f ((v+u)/(v-u))" "rArr" "2f=f((v+u)/(v-u))`
`2v-2u=v+u" "rArr" "v=3u" "rArr " "u=v//3`