A railroad train is travelling at 30 m/s in still air. The frequency of the note emitted by locomotive whistle is 500 Hz. What is the frequency of the sound waves heard by a stationary listener (a) in front of the train and (b) behind the train? (speed of sound is 345m/s.)

Explanation

To solve the problem, we will use the Doppler Effect formula for sound waves. The frequency heard by a stationary observer depends on the relative motion between the source of sound and the observer.

### Given Data:
- Speed of the train (source of sound), \( V_s = 30 \, \text{m/s} \)
- Frequency of the whistle, \( f = 500 \, \text{Hz} \)
- Speed of sound in air, \( V = 345 \, \text{m/s} \)

### (a) Frequency heard by a stationary listener in front of the train:
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