• # question_answer A racing car moving towards a cliff sound its horn, the driver observe that the sound reflected from the cliff has a frequency one octave higher than the actual frequency of the horn. If V is the velocity of sound, then the velocity of the car is: A)  $\frac{V}{2}$                       B)  $\frac{V}{\sqrt{2}}$ C)  $\frac{V}{4}$                       D)  $\frac{V}{3}$

Incase of reflection from a stationary cliff. $f'=\left( \frac{V+{{V}_{0}}}{V-{{V}_{0}}} \right)f=2f$ ${{V}_{0}}=\frac{V}{3}$