We are starting a series of articles about problems and outdated concepts in the school curriculum and suggest discussing why schoolchildren need physics, and why today it is not taught the way we would like.
Why does a modern student study physics? Either so that parents and teachers do not bother him, or then, in order to successfully pass the exam of his choice, score the required number of points and enter good university. There is another option that a student loves physics, but this love usually exists somehow separately from the school curriculum.
In any of these cases, teaching is conducted according to the same scheme. It adapts to the system of its own control - knowledge must be presented in such a form that it can be easily verified. For this, there is a system of GIA and the Unified State Examination, and as a result, preparation for these exams becomes main goal learning.
How is the Unified State Examination in Physics arranged in its current version? Exam tasks are compiled according to a special codifier, which includes formulas that, in theory, every student should know. This is about a hundred formulas for all sections of the school curriculum - from kinematics to nuclear physics.
Most of the tasks - somewhere around 80% - are aimed precisely at the application of these formulas. Moreover, other methods of solving cannot be used: I substituted a formula that is not in the list - I did not receive a certain number of points, even if the answer converged. And only the remaining 20% are comprehension tasks.
As a result, the main goal of teaching is to ensure that students know this set of formulas and can apply it. And all physics comes down to simple combinatorics: read the conditions of the problem, understand what formula you need, substitute the necessary indicators and just get the result.
In elite and specialized schools of physics and mathematics, education, of course, is arranged differently. There, as in preparation for all kinds of olympiads, there is some element of creativity, and the combinatorics of formulas becomes much more complicated. But here we are interested in the basic program in physics and its shortcomings.
Standard tasks and abstract theoretical constructions that an ordinary schoolchild should know are very quickly eroded from his head. As a result, no one knows physics after graduation from school - except for the minority who for some reason are interested in it or need it in their specialty.
It turns out that science, the main goal of which was the knowledge of nature and the real physical world, at school becomes utterly abstract and remote from everyday human experience. Physics, like other subjects, is taught by cramming, and when in high school the amount of knowledge that needs to be learned increases dramatically, it becomes simply impossible to memorize everything.
Clearly about the "formula" approach to learning.
But this would not be necessary if the goal of learning was not the application of formulas, but the understanding of the subject. Understanding is ultimately much easier than cramming.
Form a picture of the world
Let's see, for example, how Yakov Perelman's books "Entertaining Physics", "Entertaining Mathematics" work, which many generations of schoolchildren and after-school children read. Almost every paragraph of Perlman's "Physics" teaches to ask questions that every child can ask himself, starting from elementary logic and everyday experience.
The tasks that we are offered to solve here are not quantitative, but qualitative: we need not to calculate some abstract indicator like efficiency, but to reflect on why a perpetual motion machine is impossible in reality, is it possible to shoot from a cannon to the moon; you need to conduct an experiment and evaluate what the effect of any physical interaction will be.
An example from "Entertaining Physics" 1932: the problem of Krylov's swan, crayfish and pike, solved according to the rules of mechanics. The resultant (OD) should carry the cart into the water.
In a word, it is not necessary to memorize the formulas here - the main thing is to understand what physical laws objects of the surrounding reality obey. The only problem is that knowledge of this kind is much more difficult to objectively verify than the presence in the head of a student of a precisely defined set of formulas and equations.
Therefore, physics for an ordinary student turns into a dull cramming, and at best - some kind of abstract game of the mind. Forming a complete picture of the world in a person is not at all the task that the modern education system performs de facto. In this regard, by the way, it is not too different from the Soviet one, which many tend to overestimate (because earlier we, they say, atomic bombs developed and flew into space, and now we only know how to sell oil).
According to the knowledge of physics, students after graduation now, as then, are divided into approximately two categories: those who know it very well, and those who do not know it at all. With the second category, the situation worsened especially when the time for teaching physics in grades 7-11 was reduced from 5 to 2 hours a week.
Most schoolchildren really do not need physical formulas and theories (which they understand very well), and most importantly, they are not interested in the abstract and dry form in which they are presented now. As a result, mass education does not perform any function - it only takes time and effort. Schoolchildren have no less than teachers.
Attention: the wrong approach to teaching science can be devastating
If the task of the school curriculum was to form a picture of the world, the situation would be completely different.
Of course, there should also be specialized classes where they teach how to solve complex problems and deeply acquaint themselves with the theory, which no longer intersects with everyday experience. But it would be more interesting and useful for an ordinary, “mass” student to know what laws work physical world where he lives.
The matter, of course, does not boil down to the fact that schoolchildren read Perelman instead of textbooks. We need to change our approach to teaching. Many sections (for example, quantum mechanics) could be removed from the school curriculum, others could be reduced or revised, if not for the ubiquitous organizational difficulties, the fundamental conservatism of the subject and educational system generally.
But let us dream a little. After these changes, perhaps, the general social adequacy would also increase: people would be less likely to trust all sorts of torsion swindlers who speculate on the "protection of the biofield" and "normalization of the aura" with the help of simple devices and pieces of unknown minerals.
We already observed all these consequences of a vicious education system in the 90s, when the most successful swindlers even used considerable sums from the state budget, and we are observing now, although on a smaller scale.
The famous Grigory Grabovoi not only assured that he could resurrect people, but also removed asteroids from the Earth with the power of thought and “psychically diagnosed” government aircraft. He was patronized not by anyone, but by General Georgy Rogozin, deputy head of the Security Service under the President of the Russian Federation.
Scientists from planet Earth use a ton of tools to try to describe how nature and the universe as a whole work. That they come to laws and theories. What is the difference? A scientific law can often be reduced to a mathematical statement, like E = mc²; this statement is based on empirical data and its truth, as a rule, is limited to a certain set of conditions. In the case of E = mc² - the speed of light in vacuum.
A scientific theory often seeks to synthesize a set of facts or observations of specific phenomena. And in general (but not always) there is a clear and verifiable statement about how nature functions. It is not at all necessary to reduce scientific theory to an equation, but it does represent something fundamental about the workings of nature.
Both laws and theories depend on the basic elements scientific method such as generating hypotheses, conducting experiments, finding (or not finding) empirical data, and drawing conclusions. After all, scientists must be able to replicate results if the experiment is to become the basis for a generally accepted law or theory.
In this article, we'll look at ten scientific laws and theories that you can brush up on even if you don't use a scanning electron microscope that often, for example. Let's start with an explosion and end with uncertainty.
If it is worth knowing at least one scientific theory, then let it explain how the universe reached its current state (or did not reach it). Based on studies by Edwin Hubble, Georges Lemaitre, and Albert Einstein, the Big Bang theory postulates that the universe began 14 billion years ago with a massive expansion. At some point, the universe was enclosed in one point and encompassed all the matter of the current universe. This movement continues to this day, and the universe itself is constantly expanding.
The Big Bang theory gained widespread support in scientific circles after Arno Penzias and Robert Wilson discovered the cosmic microwave background in 1965. Using radio telescopes, two astronomers have detected cosmic noise, or static, that does not dissipate over time. In collaboration with Princeton researcher Robert Dicke, the pair of scientists confirmed Dicke's hypothesis that the original Big Bang left behind low-level radiation that can be found throughout the universe.
Hubble's Cosmic Expansion Law
Let's hold Edwin Hubble for a second. While the Great Depression was raging in the 1920s, Hubble was performing groundbreaking astronomical research. Not only did he prove that there were other galaxies besides the Milky Way, but he also found that these galaxies were rushing away from our own, a movement he called receding.
In order to quantify the speed of this galactic motion, Hubble proposed the law of cosmic expansion, aka Hubble's law. The equation looks like this: speed = H0 x distance. Velocity is the speed of the recession of galaxies; H0 is the Hubble constant, or a parameter that indicates the expansion rate of the universe; distance is the distance of one galaxy to the one with which the comparison is made.
The Hubble constant has been calculated at different values for quite some time, but it is currently stuck at 70 km/s per megaparsec. For us it is not so important. The important thing is that the law is a convenient way to measure the speed of a galaxy relative to our own. And more importantly, the law established that the Universe consists of many galaxies, the movement of which can be traced to the Big Bang.
Kepler's laws of planetary motion
For centuries, scientists have battled each other and religious leaders over the orbits of the planets, especially whether they revolve around the sun. In the 16th century, Copernicus put forward his controversial concept of the heliocentric solar system where the planets revolve around the sun instead of the earth. However, only with Johannes Kepler, who relied on the work of Tycho Brahe and other astronomers, did a clear scientific basis for the motion of the planets.
Kepler's three laws of planetary motion, developed in the early 17th century, describe the movement of planets around the sun. The first law, sometimes called the law of orbits, states that the planets revolve around the Sun in an elliptical orbit. The second law, the law of areas, says that the line connecting the planet to the sun forms equal areas at regular intervals. In other words, if you measure the area created by a drawn line from the Earth to the Sun and track the movement of the Earth for 30 days, the area will be the same regardless of the position of the Earth relative to the origin.
The third law, the law of periods, allows you to establish a clear relationship between the orbital period of the planet and the distance to the Sun. Thanks to this law, we know that a planet that is relatively close to the Sun, like Venus, has a much shorter orbital period than distant planets like Neptune.
Universal law of gravity
This may be par for the course today, but more than 300 years ago, Sir Isaac Newton proposed a revolutionary idea: any two objects, regardless of their mass, exert a gravitational attraction on each other. This law is represented by an equation that many students encounter in the senior grades of physics and mathematics.
F = G × [(m1m2)/r²]
F is the gravitational force between two objects, measured in newtons. M1 and M2 are the masses of the two objects, while r is the distance between them. G is the gravitational constant, currently calculated as 6.67384(80) 10 −11 or N m² kg −2 .
The advantage of the universal law of gravity is that it allows you to calculate the gravitational attraction between any two objects. This ability is extremely useful when scientists, for example, launch a satellite into orbit or determine the course of the moon.
Newton's laws
While we're on the subject of one of the greatest scientists ever to live on Earth, let's talk about Newton's other famous laws. His three laws of motion form an essential part modern physics. And like many other laws of physics, they are elegant in their simplicity.
The first of the three laws states that an object in motion remains in motion unless it is acted upon by an external force. For a ball rolling on the floor, the external force could be the friction between the ball and the floor, or it could be a boy hitting the ball in the other direction.
The second law establishes a relationship between the mass of an object (m) and its acceleration (a) in the form of the equation F = m x a. F is a force measured in newtons. It is also a vector, meaning it has a directional component. Due to the acceleration, the ball that rolls on the floor has a special vector in the direction of its movement, and this is taken into account when calculating the force.
The third law is quite meaningful and should be familiar to you: for every action there is an equal and opposite reaction. That is, for every force applied to an object on the surface, the object is repelled with the same force.
Laws of thermodynamics
The British physicist and writer C.P. Snow once said that an unscientist who did not know the second law of thermodynamics was like a scientist who had never read Shakespeare. Snow's now famous statement emphasized the importance of thermodynamics and the need even for people far from science to know it.
Thermodynamics is the science of how energy works in a system, whether it be an engine or the Earth's core. It can be reduced to a few basic laws, which Snow outlined as follows:
- You cannot win.
- You will not avoid losses.
- You cannot exit the game.
Let's look into this a bit. What Snow meant by saying you can't win is that since matter and energy are conserved, you can't gain one without losing the other (that is, E=mc²). It also means that you need to supply heat to run the engine, but in the absence of a perfectly closed system, some heat will inevitably escape into the open world, leading to the second law.
The second law - losses are inevitable - means that due to increasing entropy, you cannot return to the previous energy state. Energy concentrated in one place will always tend to places of lower concentration.
Finally, the third law - you can't get out of the game - refers to the lowest theoretically possible temperature - minus 273.15 degrees Celsius. When the system reaches absolute zero, the movement of molecules stops, which means that entropy will reach its lowest value and there will not even be kinetic energy. But in the real world it is impossible to reach absolute zero - only very close to it.
Strength of Archimedes
After the ancient Greek Archimedes discovered his principle of buoyancy, he allegedly shouted "Eureka!" (Found!) and ran naked through Syracuse. So says the legend. The discovery was so important. Legend also says that Archimedes discovered the principle when he noticed that the water in the bathtub rises when a body is immersed in it.
According to Archimedes' principle of buoyancy, the force acting on a submerged or partially submerged object is equal to the mass of fluid that the object displaces. This principle has essential in density calculations, as well as in the design of submarines and other ocean-going vessels.
Evolution and natural selection
Now that we have established some of the basic concepts of how the universe began and how physical laws affect our everyday life let's pay attention to human form and find out how we got to this point. According to most scientists, all life on Earth has a common ancestor. But in order to form such a huge difference between all living organisms, some of them had to turn into a separate species.
In a general sense, this differentiation has occurred in the process of evolution. Populations of organisms and their traits have gone through mechanisms such as mutations. Those with more survival traits, like brown frogs that camouflage themselves in swamps, were naturally selected for survival. This is where the term originated natural selection.
You can multiply these two theories by many, many times, and actually Darwin did this in the 19th century. Evolution and natural selection explain the enormous diversity of life on Earth.
General theory of relativity
Albert Einstein was and remains the most important discovery that forever changed our view of the universe. Einstein's main breakthrough was the statement that space and time are not absolute, and gravity is not just a force applied to an object or mass. Rather, gravity has to do with the fact that mass warps space and time itself (spacetime).
To make sense of this, imagine that you are driving across the Earth in a straight line in an easterly direction from, say, the northern hemisphere. After a while, if someone wants to accurately determine your location, you will be much south and east of your original position. This is because the earth is curved. To drive straight east, you need to take into account the shape of the Earth and drive at an angle slightly north. Compare a round ball and a sheet of paper.
Space is pretty much the same. For example, it will be obvious to the passengers of a rocket flying around the Earth that they are flying in a straight line in space. But in reality, the space-time around them is curving under the force of Earth's gravity, causing them to both move forward and stay in Earth's orbit.
Einstein's theory had a huge impact on the future of astrophysics and cosmology. She explained a small and unexpected anomaly in Mercury's orbit, showed how starlight bends, and laid theoretical basis for black holes.
Heisenberg uncertainty principle
Einstein's expansion of relativity taught us more about how the universe works and helped lay the groundwork for quantum physics, leading to a completely unexpected embarrassment of theoretical science. In 1927, the realization that all the laws of the universe are flexible in a certain context led to the startling discovery of the German scientist Werner Heisenberg.
Postulating his uncertainty principle, Heisenberg realized that it was impossible to know two properties of a particle simultaneously with a high level of accuracy. You can know the position of an electron with a high degree accuracy, but not its momentum, and vice versa.
Later, Niels Bohr made a discovery that helped explain the Heisenberg principle. Bohr found that the electron has the qualities of both a particle and a wave. The concept became known as wave-particle duality and formed the basis of quantum physics. Therefore, when we measure the position of an electron, we define it as a particle at a certain point in space with an indefinite wavelength. When we measure the momentum, we consider the electron as a wave, which means we can know the amplitude of its length, but not the position.
Everything that happens in our world is due to the influence of certain forces in physics. And you will have to learn each of them, if not at school, then at the institute for sure.
Of course, you can try to memorize them. But it will be much faster, more fun and more interesting to simply understand the essence of each physical force as it interacts with the environment.
Forces in nature and fundamental interactions
There are a lot of forces. Archimedes force, gravity force, Ampère force, Lorentz force, Coreolis force, friction-rolling force and others. Actually, it is impossible to learn all the forces, since not all of them have yet been discovered. But this is also very important - without exception, all the forces known to us can be reduced to the manifestation of the so-called fundamental physical interactions.
There are 4 fundamental physical interactions in nature. It would be more accurate to say that people know 4 fundamental interactions, and on this moment no other interactions were found. What are these interactions?
- Gravitational interaction
- Electromagnetic interaction
- Strong interaction
- Weak interaction
So, gravity is a manifestation gravitational interaction. Most mechanical forces (friction force, elastic force) are the result of electromagnetic interaction. The strong force holds the nucleons of the nucleus of an atom together, preventing the nucleus from decaying. The weak interaction causes the free elementary particles. In this case, the electromagnetic and weak interactions are combined into electroweak interaction.
A possible fifth fundamental interaction (after the discovery Higgs boson) are called Higgs field. But in this area, everything has been studied so little that we will not rush to conclusions, but rather wait for what the scientists from CERN will tell us.
There are two ways to learn the laws of physics.
The first- stupidly learn the meanings, definitions, formulas. A significant drawback of this method is that it is unlikely to help answer additional questions teacher. There is another important disadvantage of this method - having learned in this way, you will not get the most important thing: understanding. As a result, memorization of a rule/formula/law or whatever allows you to acquire only fragile, short-term knowledge on the topic.
Second way- understanding of the studied material. But is it so easy to understand what is (in your opinion) impossible to understand?
There is, there is a solution to this terribly difficult but solvable problem! Here are some ways to learn all the forces in physics (and in general in any other subject):
On a note!
It is important to remember and know all physical forces (well, or learn the entire list of them in physics) in order to avoid embarrassing misunderstandings. Remember that the mass of a body is not its weight, but a measure of its inertia. For example, in conditions of weightlessness, bodies have no weight, because there is no gravity. But if you want to move a body in zero gravity from its place, you will have to act on it with a certain force. And the higher the body weight, the more force will have to be used.
If you can imagine how the weight of a person can change depending on the choice of the planet, you will be able to quickly understand the concept of gravitational force, with the concepts of weight and mass, acceleration force and other physical forces. This understanding will bring with it a logical awareness of other processes that are taking place, and as a result you will not even have to memorize incomprehensible material - you will be able to memorize it as you go. It's easy enough to understand the point.
- To understand the electromagnetic effect, it will be enough just to understand how the current flows through the conductor and what fields are formed in this case, how these fields interact with each other. Consider this with the simplest examples, and it will not be difficult for you to understand the principles of operation of an electric motor, the principles of burning an electric light bulb, etc.
The teacher will primarily care about how well you understand the studied material. And it is not so important whether you memorize all the formulas. And in the case of solving control, laboratory, tasks, practical work or buying an RGR, you can always be helped our specialists, the power of which lies in knowledge and many years of practical experience!
How to prepare for the exam in physics? And does a diligent student need any special training?
“Five in physics school. We go to courses. What else does? After all, physics is not literature, where you have to read 100 books before writing an essay. Everything is simple here: you substitute the numbers in the formula - you get your points.
This is how short-sighted parents and students usually argue. "For order" visit training courses at the university. A month before the exam, they turn to the tutor: “Get us trained before the exam and show us how to solve typical problems.” And suddenly a bolt from the blue - low scores on the exam in physics. Why? Who is guilty? Maybe a tutor?
It turns out that the school five in physics was worth nothing! It is not difficult to get it - read a paragraph in the textbook, raise your hand in class, make a report on the topic "Lomonosov's Life" - and you're done. They don't teach physics problems in school., and the exam in this subject almost entirely consists of tasks.
It turns out that there is practically no physical experiment at school. The student imagines a capacitor or a loop with current as his fantasy tells him. Obviously, each fantasy suggests something different.
It turns out that in many schools in Moscow there is no physics at all. Often students report: “But we have a historian who conducts physics. And our physicist was ill for a year, and then emigrated.”
Physics was somewhere in the backyard of school education! It has long turned into a secondary subject, something like life safety or natural history.
At school with physics - a real disaster.
Our society is already feeling the consequences of this catastrophe. There is an acute shortage of specialists - engineers, builders, designers. man-made accidents. The inability of personnel to manage even with the equipment that is built in Soviet time. And at the same time - an overabundance of people with degrees in economics, law or "marketing manager".
Many go to engineering specialties only because there is a low competition. “It won’t work at MGIMO, we don’t want to join the army, so we’ll go to the MAI, we’ll have to prepare for the Unified State Exam in physics.” So they are preparing with a creak, skipping classes and wondering: why are these tasks not being solved?
This doesn't apply to you, does it?
Physics is a real science. Beautiful. Paradoxical. And very interesting. It is impossible to "pull" here - one must study physics itself as a science.
There are no "typical" USE tasks. There are no magic "formulas" in which you need to substitute something. Physics is understanding at the level of ideas. It is a coherent system of complex ideas about how the world works..
If you decide to prepare for the exam in physics and enter a technical university, tune in to serious work.
Here are some practical tips:
Tip 1.
Start preparing for the exam in physics in advance. Two years, that is, grades 10 and 11, is the optimal period of preparation. For one academic year there is still time to do something. And start two months before the exam - count on a maximum of 50 points.
Immediately warn against self-study. Solving problems in physics is a skill. Moreover, it is an art that can only be learned under the guidance of a master - an experienced tutor.
Tip 2.
Physics is impossible without mathematics. If you have gaps in mathematical preparation, eliminate them immediately. Do you know if you have these gaps? Easy to check. If you can’t decompose a vector into components, express an unknown value from a formula, or solve an equation, then do math.
After all, the solution of many USE problems in physics ends with a numerical answer. You need a non-programmable calculator with sines and logarithms. An office calculator with four steps or a calculator in a mobile phone is not good.
Buy a non-programmable calculator at the very beginning of training to master it at the level of automaticity. Bring each problem you solve to the end, that is, to the correct numerical answer.
What are the best books to prepare for the exam in physics?
1. Rymkevich's assignment.
It contains a lot simple tasks, on which it is good to stuff your hand. After "Rymkevich" the formulas are remembered by themselves, and the problems of part A are solved without difficulty.
2. Some more useful books:
Bendrikov G. A., Bukhovtsev B. B., Kerzhentsev V. V., Myakishev G. Ya. Problems in physics for applicants to universities.
Bakanina L. P., Belonuchkin V. E., Kozel S. M. Collection of problems in physics: For grades 10–11 with in-depth study of physics.
Parfent'eva N. A. Collection of problems in physics. 10-11 grade.
The most important. In order to successfully prepare for the exam in physics, you must clearly understand why you need it. After all, not only in order to pass the exam, to enter and hang out from the army?
A possible answer might be this. It is necessary to prepare for the Unified State Exam in physics in order to become a highly qualified, sought-after specialist in the future. Moreover, knowledge of physics will help you become a truly educated person.
First of all, you need to assess your current level of knowledge and understand what you want to achieve. If “from scratch” means complete ignorance of the subject, then before rushing to solve a bunch of tests from all sorts of FIPI books, you need to try to understand the processes themselves and the laws of physics, in my opinion, understanding should be the main point that you need to pay attention to . Understanding will help you a lot when solving the part where there is a choice of answer (if there is one, I don’t know). And so, in order to begin to understand something, you need to take a textbook, open sections of physics in order and read several times, you don’t need to think that after reading once, this will be enough for you, you need to re-read, so be patient. From books on theory, I would recommend G.Ya. Myakishev's textbooks, only profile level Each section has a separate book. But not for constant reading, but in case, in order to open incomprehensible places and read in more detail, the detail of the presentation often solves the problem of understanding. And for the main study of the theory: mathus.ru, everything is moderately short and sensibly painted there. I don’t see the point in reading something fundamental like Landsberg, you’ll spend a lot of time, it’s not worth it for the exam. Training videos can be a great option, but not just anyhow. I HIGHLY recommend the videos of Mikhail Penkin (MIPT teacher), there are a lot of them on the net and I don’t think you can find better ones. His videos may be able to replace all the textbooks for you, it would be even better if you start with them! Further, at the expense of cramming formulas, etc. Do not memorize formulas, try to solve problems where these formulas are applied, over time you will remember them; learn to derive formulas yourself, knowing the basic laws, you can get almost anything. Of course, you say that it is difficult, from scratch, but still worth trying. As for solving problems with calculations and a detailed answer: start with simple ones, as soon as you can solve, complicate the level of problems. To learn how to solve problems, first of all, it is worth analyzing already solved problems from the sections of interest, because methods, approaches and in general understanding of what to do will not arise on your own, no matter how long you sit on the problem. I recommend the books "Tutor in Physics" by Kasatkin I.L., a lot of analyzed problems, read, understand, try to solve a similar one. If you are ready to pay money, then I do not advise you to go to a tutor, but I advise the portal http://foxford.ru/, this is not advertising. There you can take training courses, there are unique teachers. The most important thing - do not give up, and do not think that everything is difficult, as soon as you start to understand, you will understand that you want to understand further. I will warn you about the heaps of materials from the Internet, there may be errors everywhere, and a person who has just started is practically unable to distinguish good materials for preparation from something that is not clear, do not take on faith the first thing that comes across, try to figure it out, question everything, this is the key to progress. And so, if you draw a line:
1) try to understand
2) start with something simple
3) do not get hung up on solving simple problems, if you understand - it will not fly away from your head
4) don't cram
5) use good sources (the ones I have cited have been personally verified by me)
Let it be better for you to understand and answer the exam with confidence than to memorize and solve. It is NOT possible to understand everything in a year, you can believe it, physics is not just an algorithm of actions. But you definitely need to have topics that you have delved into in order to solve all of them, or almost all of them, with confidence. So, when you "go over" through all the sections, you should pay special attention to those that are better given. Good luck!