Final answer:
Upon hearing the siren and seeing the red light of an emergency vehicle, you must pull over and stop to allow the vehicle to pass. It's critical for safety and a legal requirement. The Doppler effect can help you ascertain the direction of the approaching vehicle.
Step-by-step explanation:
When an authorized emergency vehicle approaches while sounding a siren and displaying a red light, you should pull over to the side of the road and stop, allowing the emergency vehicle to pass. It is important to remain stationary until the vehicle has sufficiently passed by. This is not only a legal requirement but also a matter of public safety, as emergency responders are trying to reach a destination as quickly as possible to provide aid. Not stopping could result in an obstruction to their path and potentially delay urgent assistance.
The Doppler shift phenomenon can help you determine whether an emergency vehicle is approaching or moving away. As a vehicle with a siren comes closer, the pitch of the siren seems higher due to the Doppler effect, and once it starts to move away, the pitch seems lower. In real-life situations, this audio cue helps drivers recognize when to pull over. However, the practical action is to pull over as soon as you hear the siren and see the red lights, without waiting to notice any shift in frequency.