A car is traveling at 25.3 m/s honks its horn as it straight approaches the side of a big building. The horn generates a long sustained note of frequency f0 = 227 Hz. The sound is reflected off the building back to the driver of car. The sound wave from the original note and that reflected off the building unite to generate a beat frequency. Find out the beat frequency which the driver hears (that tells him that he had better strike the brakes!)? Suppose the speed of sound in air is 343 m/s.