Why is the train whistle louder than when it is coming?

Because it is closer and closer to you when you come, the sound will get louder and louder, and the passing tense will be farther and farther away, so the noise will become quieter and quieter.

Because when the train comes, your ears are facing him, and the sound is louder.

Because it is to give a warning and reminder when passing through the station, it will be like this.

This is because the train has a very large amount of kinetic energy when it is moving.

Because in the past, it was actually a voice away from you, but when it comes, the voice will come head-on.

When the train comes, the whistle is louder than when it stops, which means it is louder. After driving, the sound of the whistle is lower than when it is stopped, which means that the pitch is lower.

The formation of sound is mainly caused by the vibration of the emitter and then by dense and dense sound waves in the surrounding airThis sound wave is transmitted to the human ear at a certain rate, making the eardrum vibrato similar so that we can hear the sound.

The eardrum vibrates once per second, and the pitch is felt to be high. The frequency at which the eardrum vibrates per second decreases, and the pitch is perceived to be lower. In this way, we should hear the same tone, and we should hear the same tone.

Why is the train whistle safer, but sometimes we sound high and low?

The crux of the matter is what kind of movement the train is doing. The "scattered" and "dense" sounds in the sound waves emitted by the whistle are arranged at a certain distance, but when the train is coming towards you, press the "scattered" and "tight" sound waves into the air with more force.

The interval between "sparse" and "closed" is closer, so the eardrum vibrates faster and hearing becomes higher. When the train leaves, it pulls "rare" and "tight" sound waves into the air, the vibration of the eardrum slows down, and hearing decreases. The higher the speed of the train, the greater the change in tone.

Railway workers who work on railways and trains every day, have extensive practical experience in the field and can estimate the speed of a car and the same speed based on the change in the whistle. Scientifically, we call the phenomenon of different tones and sounds of the pronunciation subject the "Doppler effect".

Because the pitch is determined by the difference in the frequency of the sound wave vibration, if the frequency is high, the tone sounds.

on the high; Otherwise, the tone sounds low. This phenomenon is called the Doppler effect, and it was discovered by Christian Doppler

Doppler (1803-1853), Doppler was an Austrian physicist and mathematician. He first discovered this effect in 1842. For reason.

To solve this phenomenon, it is necessary to investigate the propagation pattern of the sound waves emitted by the whistle when the train approaches at a constant speed. As a result, the wavelength of the sound wave is shortened, as if.

The wave is compressed. As a result, the number of waves propagating over a certain interval of time increases, which is why the observer perceives the pitch to become higher; Conversely, when the train moves into the distance, the wavelength of the sound wave becomes larger, as if the wave is stretched. As a result, the voice sounds muffled.

The quantitative analysis yielded f1=(u+v0).

u-vs) ascending volt f, where vs is the velocity of the wave source with respect to the medium, v0 is the velocity of the observer with respect to the medium, f is the natural frequency of the wave source, and u is the wave.

The speed of propagation in a stationary medium. When the observer moves towards the wave source, v0 takes the positive sign; When the observer moves away from the wave source (i.e., following the wave source), v0 is negative.

Number. When the wave source moves towards the observer, the vs front is taken with a negative sign; When the source of the front wave deviates from the observer's movement, vs takes the positive sign. From the above equation, it is easy to know when the observer and the sound source are interacting.

When approaching, f1 f; When the observer and the sound source are far away from each other. f1＜f

Whistle a long sound 1When the train starts or the rolling stock advances; 2.Approach stations, whistle signs, curves, crossings, bridges, tunnels, pedestrians, construction sites; 3.

The automatic block section can continue to run after stopping in front of the signal, and the running car is notified of the long time; 4.When an electric locomotive is ready to lower or raise the pantograph during maintenance and maintenance.

Whistle 2: When trains, rolling stock, and single machines begin to retreat.

Three long whistles: When the protective personnel are asked to withdraw.

The whistle is long and short: on the way, the locomotive requires the engine to be repaired and the steam is turned on.

The whistle is short and long: 1During the traction of the electric locomotive with two engines, the driver of the locomotive finds that the catenary is faulty and there is a danger of scratching the pantograph, and requires the machine to lower the pantograph; 2.

Two short and one long whistles: 1When the locomotive requires entry and exit sections; 2.When a signal is required to be displayed at the station.

One long and three short sounds: 1When it is found that there is an undesirable place on the route that endangers the safety of driving; 2.When a major accident occurs on the train and other situations that require rescue; 3.When the train stops in the section and cannot run immediately, notify the train commander.

A short whistle: 1When the test brake starts to decompress;

3.During shunting work, it indicates that a signal from the shunting commander has been accepted.

Whistle two short sounds:

1.Test brake machine relief.

2.Ask the train crew to ease the hand brake machine when 3When the shunting signal is repeated.

Whistle three short sounds 1When the train crew is required to tighten the hand brake machine; 2.When local braking is required.

The train horn is used to communicate with the train operation management and prevent traffic accidents. Railway signals are divided into auditory signals and visual signals, and the train horn is an auditory signal, which is a command for the operation of the train when it is running. There are rules for train horns, unlike cars that honk whenever they want.

According to the railway regulations, the horn is required in the case of train starting, entering and exiting the station, curves, bridges, tunnels, curves, pedestrians, construction sites, bad weather, etc. The train horn mainly expresses two meanings, first: the communication in the operation management of the train, such as the contact between the station attendant, the relevant driving personnel and the train driver, and reminding passengers to get off the train in the safety line.

Second: the train driver's horn is mainly to prevent the occurrence of traffic accidents, and to remind and warn them. The train horn has different meanings, with a long sound of 3 seconds, a short sound of 1 second, and an interval of 1 second, according to the instructions of the railway signal.

1.When the train starts or the rolling stock advances (when the twin engine is towed or the repair machine is used, after the main engine whistles, the repair machine should be, and the main locomotive starts after a long whistle).

2.When approaching a station, honking signs, curves, crossings, bridges, tunnels, pedestrians, construction sites, yellow signals, guidance signals, permissible signals, or bad weather. 3.

The automatic block section can continue to run after stopping in front of the signal, and the running car is notified of the long time; 4.When an electric locomotive is ready to lower or raise the pantograph during maintenance and maintenance.

With the development of our science and technology, the application of quantum mechanics is becoming more and more extensive in daily life, some of the things and phenomena we encounter, or some advanced technologies that are generated, are related to physics, such as the operation of our aircraft and the operation of high-speed trains, which are inseparable from the application of quantum mechanics.

In modern times, we often travel for business or travel to other places, so there are more and more means of travel, such as trains, battery cars, bullet trains, and high-speed rail, and even faster, that is, airplanes, then trains, in fact, we may know more when we are young. Most of them learned about the Green Train through some TV series, similar to the TV series of the Anti-Japanese War.

Usually in TV dramas, you will see that when the train is coming, or before the train is going to move, it will make a very high, a whistle sound, then the main function of this whistle sound is to play a role in informing and notifying, for example, many trains have a total of three kinds of horn sounds. When the first whistle appears, the main thing is to tell everyone that the train is ready to leave. But in the process of driving, when encountering a transfer station, it will also sound the horn, at that time, it is mainly to enter the stop station, then it will be the first signal to show that it is about to arrive, and the other signal, the sound of the horn is to indicate that it is reversing.

For this kind of honking train, then it is in the previous Anti-Japanese War or continuous development, so in recent years, some ordinary trains or high-speed rail trains are rarely famous, mainly because many high-speed trains and bullet trains, he has passed through some cities, then it is possible that this kind of honking sound will produce excessive noise, and if the noise is generated in the community, it is actually very bad, and it may also affect some of the lifestyle of the residents on both sides of the line and their rest.

Train horn sounds:

1.A long sound: start the attention signal.

2.2. Long sound: a regression signal.

3.Three long voices: summoning signals.

4.One long and one short: steam signal.

5.One long and two short sounds: steam off signal.

6.One short and one long: the signal to lower the bow on the way.

7.Two short and one long: call signal.

8.One long and three short sounds: alarm signals.

9.A short sound: test the automatic brake machine and the repeat signal.

10.2. Short sound: Mitigation and slipping signal.

11.Three short sounds: tighten the hand brake signal.

12.Continuous short sound: Emergency stop signal.

01.A long sound: start the attention signal.

02.2. Long sound: a regression signal.

03.Three long voices: summoning signals.

04.One long and one short: steam signal.

05.One long and two short sounds: steam off signal.

06.One short and one long: the signal to lower the bow on the way.

07.Two short and one long: call signal.

08.One long and three short sounds: alarm signals.

09.A short sound: test the automatic brake machine and the repeat signal.

10.2. Short sound: Mitigation and slipping signal.

11.Three short sounds: tighten the hand brake signal.

12.Continuous short sound: Emergency stop signal.

If you're satisfied, just adopt me, thank you!

A long sound: 1. When the train starts or the rolling stock advances (when the double engine traction or the use of the repair machine, after the locomotive whistles, the repair machine should answer, and the locomotive starts after a long whistle) 2. When approaching the station, the whistle mark, the curve, the crossing, the bridge, the tunnel, the pedestrian, the construction site, the yellow signal, the guidance signal, the permissible signal or the bad weather 3, the automatic block section, after stopping in front of the signal, can continue to run, and notify the running car for a long time 4, the electric locomotive is in the maintenance and maintenance, When preparing to lower or raise the pantograph;

2. Long sound: when trains, rolling stock, and single machines begin to retreat;

Three long voices: when the protective personnel are asked to withdraw;

One short and one long sound: 1. In the traction of the electric locomotive with two engines, the locomotive driver of the main service finds that the catenary is faulty and there is a risk of scratching the pantograph, and requires the replacement machine to lower the pantograph (the repair machine must be answered with the same signal) 2. When the electric locomotive driver finds a hand signal showing the catenary fault on the way, he should sound this signal to answer;

Two short and one long sound: 1. When the locomotive requires entry and exit 2, when the signal is required to be displayed at the station;

One long and three short sounds: 1. When it is found that there is a bad place on the line that endangers the safety of the train 2. When the train has a major or major accident and other situations that need to be rescued, 3. After the train stops in the section, it cannot run immediately, and the running car commander is notified;

A short sound: 1. When the test brake machine begins to decompress 2. When receiving the hand signal at the end of the test braking, when answering the wind test personnel 3. During the shunting operation, it means that the signal sent by the shunting chief has been accepted;

2. Short sound: 1. When the test brake machine is relieved 2, when the train crew is required to relieve the hand brake machine 3, when the shunting signal is repeated;

Three short sounds: 1. When the train crew is required to tighten the hand brake machine 2. When the local braking is required;

Continuous short sound: When the driver notices (or receives a notification) of an obstacle on the adjacent line and sends an emergency stop signal to the train running on the adjacent line. When the driver of the adjacent train hears such a signal, he should make an emergency stop.

When a car honks its horn and drives away from us, let's pay attention to its ringing.

Sound. Compare the sound of the coming and the sound of the driving away, and you will find that the sound of the coming Dansheng imitation is higher.

The sound of the drive away. Why is this so?

The level of sound is determined by the vibrational frequency of the air, and the higher the vibration frequency (i.e., the length of the wave), the higher the sound. Although it is the same sound, there is a change when it comes and when it goes, and this is because.

The object that makes the noise is moving.

When the object making the noise is still in place, the sound is heard at the same height. However, when the object making the sound moves in one direction, the front and back of the forward direction are compared to the forward.

The sound wave in front of the direction is shorter, and the corresponding vibration frequency is larger, so the sound sounds in front are high and low in the back.

This is a phenomenon revealed in 1842 by Mr. Doppler, a physicist from Molded Fiber Austria, called Doppler. Effect.