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sound is wavelengths, and wavelengths get compressed when coming to you (and stretched when going away). the closer the wavelengths, the higher the pitch!
The Doppler effect is the change in frequency of a sound wave. The Doppler effect causes a siren or engine to have a higher pitch when it is approaching than it does when it is receding.
A frequency higher than the original frequency.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
it is the train whistle
The Doppler radar used in weather forecasting measures the direction and speed, or velocity, of objects such as drops of precipitation. This is called the Doppler Effect and is used to determine whether movement in the atmosphere is horizontally toward or away from the radar, which aides in weather forecasting. The radar was named for J. Christian Doppler, an Austrian physicist, who was the first to articulate the reason an approaching train's whistle will sound higher than the whistle as the train moves away.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
A pleathorea of sounds, just go trackside and listen, from the piercing note of a horn, to the roar of the diesel engine to the click-clack of the wheels on the joints in the rail to the squeal of steel wheel on steel rail, there are hundreds of sounds to enjoy. "Choo Choo" doesn't cut it, sorry. Only the ignorant can agree that any train ever made this sound.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.Read more: http://wiki.answers.com/Why_is_the_pitch_of_a_train's_whistle_higher_as_the_train_approaches_and_loweras_it_moves_away#ixzz1DToTuS3j
Whistle-blowing describes the act of informing higher authorities about unethical or illegal activities. The main benefit of whistle-blowing is the possibility to end a long-standing wrongdoing.
It isn't louder (loudness has to do with intensity, and a small whistle can't generate that much intensity), it's a higher frequency. In the range that is inaudible to humans.