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 :

Answer 1

n'=(v+v')/(v-v')n

n'=2n

2n=(v+v')/(v-v')n

2=(v+v'l/(v-v')

2v-2v'=v+v'

v=3v'

v'=v/3