A loudspeaker on a homecoming float - mounted on a pole -- is stuck playing at an annoying 210 Hz tone. When the speaker is 10 m away you measure the sound to be a loud 95 dB at 208 Hz.
a. How fast and in what direction is the float moving? What is the physical reason for the change in frequency and what is the phenomenon called?
b. What is the intensity of the signal at this point? What is the power of the speaker?
c. What is the intensity of the sound from the speaker when the loudness is 55 dB? How far is the float from you at this point?
d. How long does the float take to reach the second point?