Junior 2 Physics, with 5 on sound

1.The first mistake is that space is a vacuum, and it can't transmit sound, so you can't hear the ** sound;

The second mistake is that if you can hear the sound, you should see the fire first, and then hear the sound, because the speed of light travels faster than the speed of sound.

2.** for machines, etc.

3.Energy.

1 Suddenly hear the loud ** sound of the ship's distress [vacuum cannot transmit] Suddenly hear the huge ** sound of the ship's distress, and then see the flash of ** [The speed of light is faster than the speed of sound] 2. The factory car horn.

3. Energy.

1 Unable to transmit sound in a vacuum There is no air in a vacuum Unable to **.

2 Means of Transportation, Factory Machinery and Equipment, Building Construction.

3. Energy.

1.Error - Hearing a loud ** sound, (the medium is required for sound propagation, it cannot be propagated in a vacuum) Error - Hearing the sound first and then seeing the inner light (the speed of light is faster than the speed of sound)2Traffic noise, industrial noise, living noise.

3.Energy.

1 Vacuum cannot transmit sound. The speed of light is greater than the speed of sound, and here we hear the sound and then see the inner light.

2 The sound of cars on the street, the sound of machines at a construction site, the sound of a television set being too loud...

3. Energy.

Vacuum cannot transmit sound; See the spark first, the speed of light is faster than the speed of sound.

Machine; Car; Resident life. Energy.

1.Vacuum does not transmit sound, see the light first.

2.Mechanical friction, mechanical impact, air disturbance.

3.Energy.

1.The first is to see the flash of light and then hear the ** sound; In addition, the propagation of sound requires a medium, and space is a vacuum, and sound cannot be transmitted, so sound cannot be heard.

2.Industry, Residential, Transport.

3.Small.

1. The occurrence and propagation of sound.

1. Everything that makes sound vibrates. The vibration stops, and the sound stops. A vibrating object is called a sound source.

2. The propagation of sound requires a medium, and the vacuum cannot transmit sound.

3. The propagation speed of sound in the medium is referred to as the speed of sound. The velocity of sound propagation in 15 m air is 340m s.

4. Echo is formed when the sound is reflected back by obstacles during propagation.

2. How we hear voices.

1. The propagation of sound in the ear: The sound from the outside world causes the eardrum to vibrate, and this vibration is transmitted to the auditory nerve through the ossicles and other tissues, and the auditory nerve transmits the signal to the brain, and the person hears the sound.

2. Deafness: It is divided into neural deafness and conductive deafness.

3. Bone conduction: The conduction of sound can not only be used in the ears, but also through the skull and jaw to the auditory nerve to cause hearing. This type of sound conduction is called bone conduction. Some people who have lost their hearing can hear sounds this way.

4. Binaural effect: People have two ears instead of one. The distance from the sound source to the two ears is generally different, and the time, intensity, and other characteristics of the sound reach the two ears are also different. These differences are an important basis for determining the direction of the sound source. This is known as the binaural effect.

3. Musical sound and three characteristics.

1. Music is the sound made when an object vibrates regularly.

2. Tone: The level of the voice that people feel. The pitch is related to the vibration frequency of the emitter, and the higher the frequency, the higher the pitch; The lower the frequency, the lower the pitch. The number of times an object vibrates in 1s is called frequency, and the faster the object vibrates, the higher the frequency.

3. Loudness: The amount of sound felt by the human ear. Loudness is related to the amplitude of the emitter and the distance from the sound. When an object vibrates, the maximum distance from its original position is called amplitude. The greater the amplitude, the louder it is.

4. Timbre: determined by the object itself. People are able to distinguish musical instruments or distinguish people based on their timbre.

Fourth, the harm and control of noise.

1. The four major pollutants of contemporary society: noise pollution, water pollution, air pollution, and solid waste pollution.

2. From the perspective of physics, noise refers to the sound emitted by the irregular and chaotic vibration of the sound emitter; Angular noise in environmental protection refers to the sound that interferes with people's normal rest, study and work, and the sound that interferes with the sound that people want to hear.

3. People use decibels (db) to classify sounds.

4. Methods of noise reduction: attenuation at the sound source, attenuation during propagation, and attenuation at the human ear.

5. The use of sound.

Sound can be used to spread information and transmit energy.

The percussion is produced by the vibration of the water inside the bottle.

Percussion: C B A. Are you stupid? The air column is only found in wind instruments (blown). This question looks at the weight of the water cup, the cup has a lot of water, it is heavy, the frequency is low, and the pitch is low. "123" is from bass to treble.

1. The shorter the air column, the higher the pitch.