You are standing on a train station platform as a train goes by close to you. As the train approaches, you hear the whistle sound at a frequency of . As the train recedes, you hear the whistle sound at a frequency of . Take the speed of sound in air to be v = 340 m/s.
Find the numeric value, in hertz, for the frequency of the train whistle fs that you would hear if the train were not moving.
