Review Constants Part A A friend of yours is loudly singing a single note at 420 Hz while racing toward you at 25.0 m/s on a day when the speed of sound is 340 m/s . What frequency do you hear? Express your answer with the appropriate units. HA f = Value Units Submit Request Answer Part B What frequency does your friend hear if you suddenly start singing at 420 Hz ? Express your answer with the appropriate units. HA 14 ? f = Value Units Submit Request