Consider a stationary source that generates a plane wave with frequency f0. Assume that a receiver is moving towards the source with speed v, and that the speed of sound in the media is c. a) Prove that the frequency observed is not fr = (c - v)f0/c. b) What happens if the receiver moves away from the source? c) Using the above derivations discuss the Doppler effect in the following situations when the receiver moves both towards and away from the source, and 1) c > v 2) c = v 3) c < v