Awoman is sitting at a bus stop when an ambulance with a siren wailing at 317 hz approaches at 69 miles per hour (mph). assume the speed of sound to be 343 m/s. a) how fast is the ambulance moving in meters per second? (perform the necessary unit conversion) vs= 69 mph = m/s b) what frequency does the woman hear? fa = hz c) what speed (vs) would the ambulance be traveling in order for the woman to hear the siren at an approaching frequency of 350 hz? vs= m/s d) what frequency would she hear as the siren moves away from her at the same speed (as in part c)? fa = hz