A commuter train blows its horn as it passes a passenger platformat a constant speed of 30.0 m/s. The trainhorn sounds at a frequency of 330 Hz whenthe train is at rest.
a) What is the frequency observed by a personon the platform as the train approaches?
b) What is the frequency observed by a person on the platform asthe train recedes from him?
c) What wavelength does the observer find in each case?