1. The problem statement, all variables and given/known data A helicopter drops a paratrooper carrying a siren that emits a 788 Hz audible signal. The microphone (reciever) on the plane monitors the signal from the transmitter as the paratrooper falls. Take the speed of sound in air to be 343 m/s and assume the paratroopers always remains below the helicopter. If the perceived frequency becomes constant at 412 Hz, what is the terminal speed of the paratrooper? Answer in units of m/s. 2. Relevant equations Not sure... could you guys help me out. Possibly Speed = wavelength * frequency ?? 3. The attempt at a solution Probably would need an equation first.