Some common acoustic phenomena in life are briefly explained

Suppose that there are two sounds that reach the human ear, and if the interval between the two sounds reaches the human ear is greater than or equal to, the human ear will be able to distinguish between the two sounds.

In order to experience the physical phenomenon of sound propagating at different speeds in different media, the students of the eighth-grade extracurricular activity group of a rural middle school asked one student to tap on the straight iron pipe (filled with water) that transports water to make the iron pipe make a crisp sound, and the rest of the students listened to the sound in different positions along the iron pipe. At the end of the experiment, student A said that he only heard a sound once; Student B said that he heard two rings; Student C said he heard three rings. The propagation velocity of sound is known to be v=340ms in air, v=1700ms in water, and v=5100ms in steel.

Could you please explain by calculation: If you strike once somewhere on the iron pipe, what is the distance between the position of a, b, and c. (Please write about the calculation process and the analysis of the conclusions).

The key to this question is to figure out the starting point of timekeeping, and pay attention to the different speeds of sound propagation along air, water and iron pipes, and the time it takes to reach the human ear.

Problem solving process] The order in which sound reaches the human ear (sound-transmitting substance) is: iron, water, and air.

Let the distance of sound propagation be s meters. To distinguish between (adjacent) air and water, there should be: S1 340-S1 1700

Solution: s1 To distinguish between (adjacent) water and iron, there should be: s 1700-s2 5100) solution: s1 255 (m).

The speed of sound propagation is related to the type of medium, generally it is faster in solids, slower in gases, and in liquids. At the same time, the speed of sound propagation is also related to other factors, such as the speed of sound propagation in the air increases with increasing temperature.

It is recorded in the ancient Chinese book "Mengxi Bi Tan" that when the army is marching and camping, the soldiers sleep on the ground with a quiver made of cowhide, and they can hear the sound of the horse's hooves attacking the enemy at night as soon as possible

Answer: Earth fast.

When the human auditory system is impaired, sound can also be transmitted to the auditory system through the skull, jaws, teeth, etc., causing perception, and people call this way of sound transmission bone conduction.

In the school's poetry recital, Wang Li won the first place, the teacher used a tape recorder to record Wang Li's recitation and in the classroom, for the students to enjoy, but when the students were listening intoxicated, Wang Li felt very puzzled in her heart, because she didn't sound like she was reciting, the students all smiled and said: "Don't be modest, it's you who are right!" "Can you explain Wang Li's doubts?

Answer: When the students listen to Wang Li's recitation on the spot and listen to Wang Li's recitation from the tape recorder, they both transmit sound through the air, and when Wang Li listens to her recitation from the tape recorder, it is the sound of the air, and the sound of her own voice is the comprehensive effect of air and bone sound.

Characteristics of sound.

It is recorded in the ancient book "Mengxi Bi Tan" in our country that when the army is camping, the soldiers sleep on the ground with a quiver made of cowhide, and they can hear the sound of the horse's hooves of the enemy attacking at night as soon as possible, and the reason is that the solid can transmit sound

Test Center: Tone; the conditions under which the sound is propagated; The relationship between frequency and pitch

Analysis: To answer this question, you need to grasp that the pitch of the sound is called the pitch, and the pitch is related to the frequency of the vibration; Solids transmit sound better than gases and liquids

Answer: Solution: The female student's voice is "sharp" because the female student's vocal cords vibrate faster and the pitch is higher when she speaks

It is recorded in the ancient book "Mengxi Bi Tan" that when the army is camping, the soldiers sleep on the ground with a quiver made of cowhide, and they can hear the sound of the horse's hooves of the enemy attacking at night as soon as possible, and the reason is that the solid can transmit sound, and the sound transmission effect is good

Therefore, the answer to this question is: tone, fast, solid

Comments: This question mainly tests students' understanding and mastery of pitch and frequency, as well as the good effect of solid sound transmission

Sometimes since.

Bai comes from the water pipe in the adjacent water du

When the faucet is released, there are occasional bursts of dao sounds. This is due to the resonance of the water pipes caused by the water rushing back from the water hose.

Looking in mirrors, periscopes, and car rearview mirrors are light phenomena;

The phenomenon of --- sound of soil made from cups.

Fish in the water can be frightened away by the sound of people on the shore talking and footsteps--- sound phenomenon Radar locator --- sound phenomenon.

Echo --- acoustic phenomenon.

The vibration of the drum surface --- sound phenomenon when the drum is beaten.

There is a --- sound in the partition wall.

Noise --- acoustic phenomena.

A lunar eclipse --- the linear propagation of light.

A solar eclipse --- the linear propagation of light.

Measuring the height of a building or flagpole --- the straight propagation of light The small hole imaging --- the straight propagation of light.

Carpentry planed timber is aligned with the eyes--- the straight line propagation of light Shadows --- straight line propagation of light.

1. Soil **2 fish made of cups can be scared away by the words and footsteps of people on the shore--- sound phenomenon.

3 radar locator 4 echo.

5. The drum face vibrates when the drum is beaten.

Sound phenomenon knowledge combing (completely summarized by myself, no plagiarism!) ）

1.Sound is produced by vibrations.

2.The propagation of sound requires a medium (solid, liquid, gas).

Where, in general, the propagation speed of sound in solid liquids and gases.

Gas 15 has a speed of 340 meters per second.

No sound can be transmitted in a vacuum.

3.There are three elements of sound: loudness (the magnitude of the sound), timbre (the quality of the sound), and pitch (the height of the sound).

The greater the amplitude, the greater the loudness.

The faster the frequency, the higher the pitch.

4.Sound is divided into noise and music. Noise refers to the sound with irregular waveforms, and musical sound refers to the sound with regular waveforms. The specifics will vary from person to person.

The unit of sound is decibels (dB), and the sound that ordinary people can hear is 0 decibels, and more than 90 decibels will cause hearing damage to people.

5.The frequency range that can be heard by the human ear: 20 20,000 hertz (Hz), below 20 Hz is called infrasound, and more than 20,000 Hz is called ultrasound.

The occurrence of infrasound waves is often accompanied by a huge amount of energy.

Ultrasonic waves have the characteristics of good directionality, strong penetration, and easy access to concentrated energy. It is widely used in life.

6.Comprehensive practical activities, experimental questions, are not listed here.

It's a junior high school physics problem, and the upstairs is overly complicated.

1. It is correct that the object that is making the sound must be vibrating. When the vibration stops, the sound does not tremble and disappear because it takes time for the sound to propagate.

2.Doctors use a stethoscope to examine the patient's body because the stethoscope amplifies sound and travels late. Wrong, the stethoscope is a concentrated propagation of sound in one direction!

Answer C All sounding socks are vibrating vertically, A is false.

Hearing its voice and knowing its person" is judged mainly by the timbre of the voice, b wrong.

Some sections of the road in the urban area "no honking" This is to reduce the noise at the sound source of the sound transmission of the sound of good talk, C wrong.

The use of ultrasound waves to crush the "stones" in the human body indicates that sound waves have energy to collide, d pairs.

1。How does the laughing tree make a laughing sound (The outer shell of the fruit has many small holes, and when the wind blows, the seeds in the shell hit the shell wall and make a sound. )

2。Why are giraffes always so quiet (Giraffes don't have vocal organs.) )

3。Restoration of sound on the record. Early mechanical records had irregular grooves, and when the record turned, the stylus vibrated laterally (oscillating from side to side).

Nowadays, when the record is turned, the stylus vibrates longitudinally (up and down).Nowadays, people have also invented the use of magnetic tape and laser turntables to record and reproduce sound.

The answer is c, which is explained as follows:

In fact, the options give hints, first of all, you can hear the sound to have a sound source, that is, the vibration of the object, and secondly, there must be a medium for sound propagation, and sound can be transmitted without a medium like electromagnetic waves. So options A and B are all wrong. As for item d, it is to set a trap by blurring our common sense, and in life we feel that the object is not vibrating but there is still some weak sound, but in fact, the stop vibration that we observe with the human eye is actually not the real vibration stop, and the reason why we can hear the sound is because he is still vibrating.

A is wrong, there is a sound source and a sound transmission medium to reach the human ear.

b False, there must be a sound source.

C Yes, sound is produced by vibration, if you can hear the sound, there must be an object vibrating d wrong, sound is produced by vibration, without vibration there is no sound...