1, 3-year simulated 5-year senior high school entrance examination

Three-year Simulation of Five-year Senior High School Entrance Examination is a book published by Education Science Press and Capital Normal University Press. The author is Qu Yixian. This book is the crystallization of the wisdom of many teachers, a secret book of many front-line teachers and a helping arm for candidates. This book has an insight into the laws of the test questions and propositions in the senior high school entrance examination, so that students can prepare for the exam scientifically.

2, "three point one test from the book"

The ninth revised edition of "Three Points and One Test Series" is compiled according to the latest instruction spirit of the Ministry of Education on education reform and the latest Chinese textbook for senior high schools in 2005. This revision better explains the educational reform requirements of "from knowledge to ability, from exposure to concealment", takes the cultivation of ability as the fundamental direction, prompts key and difficult points, analyzes knowledge points and consolidates new knowledge on the basis of comprehensively prompting the hidden laws of knowledge types.

Physical knowledge points

First, the three characteristics of music

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

2. Tone: The level of sound that people feel. When you use a piece of hard paper to draw a slow picture on the comb teeth, you can find a fast pitch. When you pull rubber bands with different thicknesses with the same force, you can find that the rubber bands vibrate quickly and the sound is improved.

Combining the two experimental phenomena, you get the same conclusion: the tone is related to the vibration frequency of the speaker, and the higher the frequency, the higher the tone; The lower the frequency, the lower the pitch. The number of times an object vibrates at 1s is called frequency. The faster the object vibrates, the higher the frequency. Frequency per second is also recorded as Hz.

3. Loudness: the volume of sound felt by the human ear. Loudness is related to the amplitude of the generator 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 greater the loudness. The main way to increase loudness is to reduce the divergence of sound.

4. Tone: It is determined by the object itself. People can distinguish musical instruments or people according to their timbre.

Second, the harm and control of noise

1. Four major pollutions in contemporary society: noise pollution, water pollution, air pollution and solid waste pollution.

2. From the physical point of view, noise refers to the sound produced when the vocal body vibrates irregularly and disorderly; Environmental protection angle noise refers to the sound that interferes with people's normal rest, study and work and the sound that people want to hear.

3. People use decibels (dB) to divide the sound level; The lower limit of hearing is 0 dB; In order to protect hearing, the noise should be controlled within 90dB；; In order to ensure work and study, the noise should be controlled within 70dB；; In order to ensure rest and sleep, the noise should be controlled within 50dB.

4. Ways to reduce noise: at the sound source, in the process of propagation, at the human ear.