6 (a) What frequency is received by a person watching an oncoming ambulance moving at33.3m/sand emitting a steady893Hzsound from its siren? Thespeed of sound on this day is345 m/s. (b) What frequency does she receive after the ambulance has passed?

7 A) light-rail commuter train blows its 200 Hz horn as it approaches a crossing. The speed of sound is 341 m/s.(a) An observer waiting at the crossing receives a frequency of 214 Hz. What is the speed of the train? m/s (b) What frequency does the observer receive as the train moves away?