Sound
Sound
I hear the vibration is transmitted through the air by a sound … object vibrating by reaching the edge. In addition, the phenomenon that vibration is handed down to in sequence is called a wave.
※The sound does not come in vacuo that vibration is that a material vibrates and comes. In addition, not only the gas such as the air but also a solid and the liquid can convey a sound.
It is approximately 340m/s at 15 degrees Celsius in the speed … air of the sound. It is approximately 1,500m/s underwater. It becomes fast in order of gas → liquid → solid for wind of approximately 6,000m/s with the solid such as iron.
※The speed of the sound varies according to temperature and becomes fast so that temperature is high.
| State of the object | The speed of the sound |
| Gas | Approximately 340m/s |
| Liquid | Approximately 1,500m/s |
| Solid | Approximately 6,000m/s |
Size and high sound
I can serve it by strongly playing the strings such as big sound … guitars.
I can serve it by playing the strings such as small sound … guitars weakly.
I thin the strings such as expensive sound … guitars and shorten it and can start it by strongly swelling.
I make the strings such as low sound … guitars big and lengthen it and it is weak and can start it by forming.
※A loud sound and the low sound are different in volume, and a high-pitched sound and the low sound are different in a musical scale like do re mi fa so la ti do.
I can watch it in the device which can look at big things and small things or the pitch of the oscilloscope … sound as a wave pattern like a figure.
About the length from the center of the amplitude … vibration to the vibrating edge, it is with the sound that is loud if this is long.
About the number of waves per one second of number of vibrations, a vibrating object Hz (express it in units called sign Hz).) It becomes the high-pitched sound so that this is high.
For example, it is with 1/0.004 = 250, and the number of the wave per one second knows that there are 250 waves per one second because there is one wave like an upper figure in 0.004 seconds if 1 memory is 0.001 seconds. Thus, I understand that this sound is 250Hz.
※The number of vibrations is called alias frequency. In addition, the musical scale of the music is decided to undergo number of vibrations by a sound, and the number of vibrations doubles when it becomes the sound in the octave. (e.g.:) As for the sound of the lah of the middle of the piano, lah in the octave is 880Hz at 440Hz; the lah in the octave 1,760Hz)
※The range of the number of vibrations to sound like a human ear is 20Hz – 20,000Hz.
The phenomenon that, on the other hand, begins to sound when I let a tuning fork sounding a sound of the resonance … same number of vibrations face each other and put it and sound one.
※The resonance happens only in things sounding a sound of the same height.
Doppler effect
A phenomenon that the number of vibrations of the sound to appear from a sound source when it is an observer and is different in a state of the exercise is different from a Doppler effect … sound source in pitch hearing even uniformity and hears.
For example, the sound is low and hears it when the sound is high and goes away from hearing, oneself when I approach oneself while an ambulance sounds a siren.
※As for the unit of the sound, problems using the speed of the mathematics are often made questions for. When the sound that sounded it towards the wall of the school building bounces, and oneself hears it, you must be careful about the sound making a round trip to 1. It is important the complicated problem writes a figure, and to untie. In addition, the problem that wave patterns of the oscilloscopes are seen in in a regular examination well. The problem to demand the number of vibrations of a problem and the sound to choose a sound of the same height as among a wave pattern from a wave pattern is easy to be made questions for.