Chapter 14, Problem 54PCE

The Bullet Train The Shinkansen, the Japanese “bullet” train, runs at high speed from Tokyo to Nagoya. Riding on the Shinkansen, you notice that the frequency of a crossing signal changes markedly as you pass the crossing. As you approach the crossing, the frequency you hear is f, as you recede from the crossing the frequency you hear is 2f/3. What is the speed of the train?