Chapter 14.5, Problem 44E

A sound with frequency f_s, is produced by a source traveling along a line with speed v_s. If an observer is traveling with speed v₀ along the same line from the opposite direction toward the source, then the frequency of the sound heard by the observer is

$f_0=\left(\frac{c+v_0}{c-v_s}\right)f_s$

where c is the speed of sound, about 332 m/s. (This is the Doppler effect.) Suppose that, at a particular moment, you are in a train traveling at 34 m/s and accelerating at 1.2 m/s². A Train is approaching you from the opposite direction on the other track at 40 m/s. accelerating at 1.4 m/s² and sounds its whistle, which has a frequency of 460 Hz. At that instant, what is the perceived frequency that you hear and how fast is it changing?