Application of junior high school physics knowledge in social production and life Physics is the science that has the closest relationship with human production and life. In physics teaching, it has become an unshirkable duty for physics teachers to link physics knowledge with production practice and life practice, so that students can understand the application of physics knowledge in production practice and life practice as much as possible. First, the extensive application of mechanical knowledge 1. The application of gravity We live on the earth, and gravity is everywhere. For example, when building a wall, workers often check whether the wall is vertical with a heavy hammer line, which makes full use of the principle that the gravity direction is vertical downward; The lower end of badminton is heavier, which is to protect the feathers by lowering the center of gravity. Drivers can continue to slide when they turn off the engine when going downhill, saving energy by gravity. In agricultural production, seedling throwing technology also uses the direction of gravity to vertically downward. If there is no gravity, the world is unimaginable, water can't be poured into the mouth, people can't fall back to the ground after taking off, flying dust floats in the air forever, and the whole nature is turbid. When teaching gravity, let students have a heated discussion, fully tap students' imagination, and know that gravity is closely related to our production and life. 2. Friction is an important force, which is widely used in social production and life. For example, when people walk, it is very difficult to walk on the smooth ground because the friction of the contact surface is too small; When the car slides uphill, sprinkle some rough stones or straw on the road surface, and the car can move forward smoothly, and increase friction by increasing roughness; Making the sole into various patterns also increases the roughness of the contact surface and friction; Roller skates worn by skaters change sliding friction into rolling friction, reduce friction and increase sliding speed; Lubricating oil is added to all kinds of machines to reduce the friction between gears and ensure the good operation of the machines. It can be seen that human production and life are actually related to friction, so we should make full use of beneficial friction and minimize harmful friction. 3. The application of elasticity can be used to carry out a series of social production and life activities, and the force has size, direction and action point. If the high-rise building needs to lay a solid foundation, the bridge design needs to accurately calculate the force of each part; Tug of war requires thick rope to prevent excessive tension from breaking; A thicker steel wire should be added to the center of the high-voltage line to support a larger erection span; The explosive power generated by athletes in an instant and so on. It can be seen that the knowledge of physical mechanics is very useful in production and life practice. From cosmic celestial bodies to microscopic molecules and atoms, there are all kinds of forces everywhere. As long as teachers organically combine textbook knowledge with production and life practice, they can greatly stimulate students' interest in learning, thus cultivating them to establish the spirit of advocating science, researching science and applying science. Second, the application of thermal knowledge Weather is closely related to various human activities, including a lot of physical thermal knowledge. If people often drink boiled water and eat cooked food, they need to heat water and food. In the heating process, they need to know the basic knowledge of fuel combustion or electric heating. Sprinkle some water on the ground in hot summer to cool down through evaporation of water; How to keep warm in cold winter, car engines often use water to dissipate heat and protect seedlings from freezing, and rice fields often use water at night, all of which make full use of the characteristics of high specific heat of water; Rice grows in summer, because rice is a plant that likes high temperature; The manufacture of various mechanical bearings and train tires makes full use of the principle that solids expand when heated and contract when cooled. These are all important applications of thermal knowledge in production and life. Third, the application of photoacoustic phenomenon. Man needs light to survive. It depends on the sun during the day and needs light at night. Imagine that without light in the universe, the whole world would fall into darkness and all living things would not survive. This shows the importance of light. However, what laws light follows and how human beings use these laws to serve themselves are the purpose of human research on light. For example, solar eclipse follows the straight line propagation of light in the same uniform medium; In the classroom, fluorescent tubes are usually used instead of incandescent lamps. In addition to energy saving, it is more important that incandescent lamps are easy to form shadows, while fluorescent tubes are parallel lights, which can avoid shadows and enable us to work and study well. The reason why cars driving at night don't turn on the lights is to avoid the driver's sight being affected by the reflected light from the windshield. The car's reflector uses convex mirror instead of flat mirror to expand the observation range. Myopia patients need to wear concave lenses to correct the imaging of objects on human retina. The flashlight can use the light energy emitted by the concave focus to emit parallel light to "receive light". In addition, the length of the classroom is limited to about 10m to avoid the original sound and secondary echo, so that the two sounds are superimposed together to strengthen the original sound; The measurement of the distance between two mountains and the depth of the seabed is also based on the principle of sound propagation. The application of electrical knowledge Since Farah discovered the phenomenon of electromagnetic induction, mankind has entered the era of electrification. Electricity for living, transportation, factories and enterprises all come from generators, and electricity has become an indispensable main energy source for human beings. The application of electricity can be seen everywhere in our life. For example, a flashlight used for walking at night converts chemical energy into electrical energy; Dry batteries will not get an electric shock accident, and improper lighting electricity will endanger our lives. This is because the safe voltage is not higher than 36V, and the voltage of the lighting circuit is 220V, which is much higher than that of safe voltage. Rice cookers and electric frying pans for cooking convert electric energy into internal energy, and electric locomotives run on electric energy, so all household appliances need electricity. Assuming that there is no electricity, the motor does not turn, the electric locomotive does not run, and the electrical appliances do not work, human society will go backwards. Therefore, electricity is a good partner of mankind. As long as we strictly follow the principle of safe use of electricity, we can tame it and use it to serve mankind. In a word, physical knowledge has a wide range of applications from life reality to high-tech frontier. As a physics teacher, we should not only let students know the importance of learning physical knowledge and its important role in contemporary society, but also guide students to pay attention to the latest development of physics, so that students can combine their physical knowledge with current social practice and life reality, keep pace with the times, adhere to Scientific Outlook on Development, and use physical knowledge to promote the harmonious development of society and better benefit mankind. The answer supplements the common sense of physics in life /dispbbs.asp? board id = 18 & amp； id=57773 /index_3.asp？ XXPXDDD = 396223 & AMPXPXCCC = 575980 Including why high jumpers should run up? Why can you "drink" soda through a straw? Why can thermos bottles keep warm? There are too many things. It is very useful to list them side by side. When writing this article, give a few more examples, and two thousand words will be put together.