Abstract: Physics is a natural subject with a long history. With the development of science and technology and the progress of society, physics has penetrated into all fields of human life; Physics exists around physicists; Physics also exists around students; In learning, students should establish scientific consciousness, focus on the big picture, start with small things, experience observation, thinking, practice, innovation and other activities, gradually master scientific learning methods and train scientific thinking methods, and soon you will have the mind of a scientist, laying a solid foundation for your amazing development and beautiful life in the future.
Key words: Physics permeates all fields of human life, around which physicists and students have scientific consciousness and scientific learning methods.
As an important branch of natural science, physical science not only plays an important role in promoting the progress of material civilization and deepening human understanding of nature, but also has an indispensable influence on the development of human thinking. From natural philosophy in Aristotle's time to classical mechanics in Newton's time, and then to relativity and quantum mechanics in modern physics, all these are tangible manifestations of physicists' scientific quality, scientific spirit and scientific thinking. With the development of science and technology and the progress of society, physics has penetrated into all fields of human life. For example, just looking for optical knowledge in the car has the following points:
1. The rearview mirror outside the driver's cab is convex.
By using the divergent function of convex mirror to light and the characteristics of upright, narrow and virtual image, the objects you see are small and the observation range is wider, thus ensuring driving safety.
2. The reflector of automobile headlights is a concave mirror.
It is made by using the property that concave mirror can reflect the light from the light source placed at its focus into parallel light.
Car headlights should always be equipped with glass lampshades with horizontal and vertical stripes.
Car headlights consists of a light bulb, a reflector and a front glass cover. According to the knowledge of lens and prism, car headlights glass cover is equivalent to the combination of lens and prism. When driving at night, drivers should not only see the road ahead, but also see the fixers, road signs, forks and so on. The lens and prism refract the light, so the lampshade diffuses the light to the required direction according to the actual needs, so that the light illuminates the road in front of the car and the roadside scenery evenly and softly. At the same time, this astigmatism lampshade can slightly refract some light to illuminate road signs and milestones, thus ensuring driving safety.
After the car is fitted with brown glass, it is difficult for pedestrians to see the faces of people in the car.
The tawny glass can reflect some light and absorb some light, so the light penetrating into the car is very weak. In order to see the passenger's face clearly, it is necessary to reflect enough light from the face and transmit it to the outside of the glass. Because the light inside the car is weak and there is not enough light to transmit, it is difficult to see the passenger's face clearly.
Except buses, the front windows of most cars are inclined.
When the front window glass of a car is tilted, the image of the passenger in the car reflected by the glass is in front of the country, and pedestrians on the road can't appear in the air above, so the image of the passenger in the car is separated from the pedestrians on the road, and the driver won't have an illusion. The front window of a bus is much higher than that of a car. Even the vertically installed front window looks the same height as the window, and pedestrians on the road cannot appear at this height, so drivers will not confuse the image of passengers outside the window with pedestrians on the road.
Another example is as follows:
Spiced tea eggs are very popular with people, especially when it is hot. Careful people will find that when the eggs are just taken out of the boiling gravy, if they are eager to shell and eat them, it is inevitable to peel them off with the "meat". To solve this problem, there is a trick, that is, soak the eggs just out of the pot in cold water for a while, and then peel them, so that the eggshells can be peeled easily.
General substances (with a few exceptions) have the characteristics of thermal expansion and cold contraction. However, when different substances are heated or cooled, the speed and amplitude of expansion and contraction are different. Generally speaking, substances with low density are easier to expand and contract than substances with high density, and substances with fast heat transfer are easier to expand and contract than substances with slow heat transfer. An egg consists of a hard shell, a soft protein and a yolk, and their expansion and contraction are different. When the temperature changes slightly or slowly and evenly, nothing can be displayed; Once the temperature changes dramatically, the expansion and contraction speeds of eggshells and protein are inconsistent. When the boiled egg is immediately immersed in cold water, the temperature of the eggshell will decrease and shrink rapidly, while protein is still at its original temperature and does not shrink. At this time, a small part of protein will be squeezed into the short position of the egg by the eggshell. Then, due to the decrease of temperature, protein gradually contracted. By this time, the contraction of the eggshell was already very slow, and protein was separated from the eggshell. Therefore, when peeling, the shell and the "meat" will not come off together.
It is very useful for us to understand this truth. If all things that need to undergo great temperature changes are made of two different materials together, their thermal expansion performance must be considered when selecting materials, and the closer they are, the better. Reinforced concrete is widely used when engineers design houses and bridges. Because the expansion degree of steel bars and concrete is similar. Although the temperature is different in spring, summer, autumn and winter, it will not produce harmful forces, so reinforced concrete buildings are very strong.
In addition, some electrical components are made of two metals with very different thermal expansion characteristics. For example, the thermal expansion of copper sheet is greater than that of iron sheet, and the bimetal nailed together by copper sheet and iron sheet will bend due to different expansion degrees when heated under the same conditions. Using this characteristic, many automatic control devices and instruments have been manufactured. There is a small bimetal in the "starter" of the fluorescent lamp, which can automatically expand and contract with the change of temperature, thus playing the role of automatically turning on the fluorescent lamp.
There are countless examples of this. Physics is a practical science, which is closely related to industrial and agricultural production and daily life. Physical laws themselves are generalizations and abstractions of natural phenomena.
When it comes to physics, some students find it difficult; When it comes to physical inquiry, some students feel unfathomable; Speaking of physicists, some students think they are not ordinary people. It is true that there are only a handful of physicists, but as long as you are diligent in observation, good at thinking and brave in practice and innovation, you will find that physics is around you. As Marx said, "Science is experimental science, and science lies in arranging perceptual materials in a rational way". Physics is not only a discipline but also a science.
Physics exists around physicists. Galileo, an observant Italian physicist, took great interest in the swing of the copper chandelier hanging in the air in Pisa Cathedral when he was attending church. Later, after repeated observation and research, he invented the synchronization of the pendulum. In order to understand the essence of "God's wrath", Franklin, an American physicist who is brave in practice, risked his life to bring "God's fire" to the world with an ordinary kite on a day of lightning, thunder and rain, and invented the lightning rod. Henry Achar, a British innovative scientist, went to the post office to handle affairs. At that time, a foreigner next to me took out a large edition of new stamps to cut and post on the envelope, but he didn't have a knife. I borrowed it from Aga, and Aga didn't have it. The foreigner had a brainwave, took off the pin on the suit and tie, neatly pierced a circle of holes around the stamp, and then neatly tore it off. When the outsiders left, they left Aga with a series of profound thoughts, and therefore invented the stamp punching machine, and the stamps with tooth patterns were born. Archimedes discovered Archimedes principle in ancient Greece; German physicist roentgen discovered x-rays; ..... There are countless examples of physicists who have made great achievements in studying trivial matters around them.
Physics also exists around students. After learning the basic knowledge of measurement, the students began to make soft rulers. A classmate is ingenious, wrapping the kraft paper soft ruler with transparent glue, which is more firm. Then a box wrapped in bubble gum is used as the shell of the soft ruler, the center of the box is made of iron wire, and the end of the soft ruler is fixed on the shaft, thus a tape measure that can be cleaned and reused is born. At the same time, inspired by the soft ruler, this student solved an exercise through experiments: when measuring the length of an object with a soft ruler, if the soft ruler is lengthened, is the measured value too large or too small? He did such a simulation experiment: draw a straight line on a white paper, mark it with a scale, then stick it with transparent glue, and then pull it down to make a "soft ruler". With the "soft ruler", he not only found the answer to the above questions, but also clearly saw that the graduation value became larger, and he knew why. After learning the knowledge of electricity, the students explored the maximum voltage that the earthworm can bear: when a voltage of 1.5V is applied to it, the earthworm quickly secretes mucus and struggles to jump out of the bottle. Earthworms are electrically divided into two parts when a voltage of 3V is applied. When measuring the power of "2.4V, 0.5A" small bulb and studying its luminous situation, some students are not satisfied with adding 2.4V voltage to the bulb, but do destructive experiments with their own small bulbs, constantly increasing the voltage at both ends of the bulb until the voltage reaches 9V, and the filament of the bulb burns out. When some students are learning the knowledge of evaporation, they take pains to sit at the table and observe the same two drops of water (one of which is flat), and then observe them carefully, and then analyze and compare them to get the factors that affect evaporation; ..... It is not uncommon for students to capture trivial things around them and explore.
Things around us are inexhaustible, and physics disciplines closely related to real life are often used. Explain and summarize the laws of physics with examples around you, so that students can sound familiar and easy to accept. As long as we always pay attention to and summarize, we will constantly find something beneficial to physics teaching, enrich our classroom, enliven the teaching atmosphere and simplify concepts and laws. The new curriculum standard tells us that "the physics curriculum in compulsory education should be close to students' life, conform to students' cognitive characteristics, and stimulate and maintain students' interest in learning." By exploring physical phenomena, the hidden physical laws are revealed and applied to actual production and life, so as to cultivate students' lifelong interest in exploration, good thinking habits and preliminary scientific practice ability. "
Today, all the amazing scientific and technological achievements of mankind, such as sheep cloning, internet, nuclear power plants, aviation technology and so on. All of them are based on the observation and research of trivial things around scientists in the early years. In learning, students should establish scientific consciousness, focus on the big picture, start with small things, experience observation, thinking, practice, innovation and other activities, gradually master scientific learning methods and train scientific thinking methods, and soon you will have the mind of a scientist, laying a solid foundation for your amazing development and beautiful life in the future.
References:
Ministry of Education: New Curriculum Standards for Junior High School Physics (Experimental Draft)
Xing: Science and Technology Development and Middle School Physics Curriculum Reform: Middle School Physics Teaching Examination, No.4, 1998.
Li, training students' innovative thinking with prototype inspiration, Physics Teaching Theory, No.8, 2000.
[America] L. Love Postan [America] P. harwit's interesting physics question and answer set