The siren of a police car has a frequency of 1580 Hz. The police car in chase of a criminal is moving at 54 m/s directly toward a high-rise building that reflects the siren sound back to the police car. Velocity of sound 343 m/s.

a) What Doppler shifted frequency would an occupant of the high-rise hear? b) What frequency would the policeman in the car hear reflected off the high-rise and Doppler shifted by the motion of the police car? c) What beat frequency would the policeman hear as a result of the interference between the siren heard directly and the Doppler shifted sound?