Question

All train operators are instructed that when operating trains in yards they are to operate from a standing position in the cab. The reason for this instruction is that from this position it is easier to ________.

1) control the train
2) see the signals
3) communicate with other operators
4) monitor the train's speed

Answer 1

A stationary person will hear a higher frequency as the train approaches and a lower frequency after it passes, due to the Doppler Effect. The train's engineer hears a constant frequency since they are moving with the source of the sound.

Step-by-step explanation:

Doppler Effect in Train Sound Frequencies

The frequency of a sound as perceived by an observer is affected by the relative motion of the source and the observer—a phenomenon known as the Doppler Effect.

(a) A stationary person at the side of the tracks will observe a higher frequency as the train approaches and a lower frequency after the train passes. This is due to the fact that as the train approaches, the sound waves are compressed, and as the train departs, they are stretched out.

(b) The train's engineer, however, will observe a constant frequency—which is the actual frequency of the train's horn—because the engineer is moving with the source of the sound.

Understanding the Doppler Effect is important for train operators, especially in the aspect of signaling and communication, which is crucial for train safety.