An ambulance siren has a fundamental frequency of 261 Hz .The ambulance is headed
towards an accident site with a speed of 100km/h .Two police officers on separate
motor cycles head for the same accident site: one follows the ambulance with a speed of 90km/h
and the other approaches the accident site from the other direction with a speed of 90 km/h .
What frequency does the ambulance siren has for each of the police
officers? Take the speed of sound equal to 340m/s .