With what velocity an observer should move relative to a stationary source so that he hears a sound of double the frequency of source?
Velocity of sound towards the source
Velocity of sound away from the source
Half the velocity of sound towards the source
Double the velocity of sound towards the source
By using n' = n(vv-vs)
2n = n(v-v0v-0) ⇒vo = -v = -(Speed of sound)
Negative sign indicates that observer is moving opposite to the direction of velocity of sound, as shown