A whale is swimming at a steady speed either directly at or directly away from an underwater cliff (you don’t know which). When the whale is 300 m from the cliff, it emits a sound and it hears the echo 0.399 s later.
(a) Which way is the whale traveling: (i) toward the cliff or (ii) away from the cliff? Explain your reasoning.
(b) How fast is the whale traveling?
(c) If the emitted sound has a frequency of 12.1 kHz, by how much has the frequency changed by the time the whale hears the echo?