An ambulance moving to the east with a speed of10m/s sounds its siren at a frequency of 680 herz. An automobile approaches the ambulance movingto the west. The driver hears a frequency of 750 herz. Thespeed of sound in air is 350m/s. What is the speed of theautomobile? An ambulance moving to the east with a speed of10m/s sounds its siren at a frequency of 680 herz. An automobile approaches the ambulance movingto the west. The driver hears a frequency of 750 herz. Thespeed of sound in air is 350m/s. What is the speed of theautomobile?
Explanation / Answer
Given that the velocity of the source( ambulance) is Vs= 10 m/s ( east) The frequency of source is (ambulance) f = 680 Hz The frequency heard by the observer is f1 = 750Hz The speed of sound in air is v = 350 m/s --------------------------------------------------------------------------------- The observer andthe source are moving towards each other thenthe frequency heared by the observer is f1 = f ( v + Vo ) / (v- Vs) f1 (v-Vs) / f = ( v + Vo ) V0 = f1 (v- Vs) / f - v = ------------ m/s This is the velocity of the automobile .