A monorail train approaches a platform at a speed of 10.0 m/s while it blows its whistle. A musician with perfect pitch standing on the platform hears the whistle (its frequency is 261 Hz.). There is no wind and the temperature is a chilly 0 0C.
a) What is the observed frequency of the whistle when the train is at rest?
b) Find the distance between the train and the musician when the train is at rest.