1.1. Bodies and environments. Understanding Systems

While studying physics last year, you learned that the world we live in is a world physical bodies and Wednesdays. How is the physical body different from the environment? Any physical body has a shape and volume.

For example, a wide variety of objects are physical bodies: an aluminum spoon, a nail, a diamond, a glass, a plastic bag, an iceberg, a grain of table salt, a lump of sugar, a raindrop. And the air? He is constantly around us, but we do not see his form. For us, air is a medium. Another example: for a person, the sea is, although very large, but still a physical body - it has a shape and volume. And for the fish that swims in it, the sea is most likely the environment.

You know from your life experience that everything that surrounds us consists of something. The textbook that lies before you consists of thin sheets of text and a more durable cover; an alarm clock that wakes you up in the morning - from a variety of different parts. That is, we can say that the textbook and the alarm clock are system.

It is very important that the constituent parts of the system are connected, since in the absence of connections between them, any system would turn into a "heap".

The most important feature of each system is its compound and structure. All other features of the system depend on the composition and structure.

The concept of systems is necessary for us in order to understand what physical bodies and environments consist of, because all of them are systems. (Gas media (gases) form a system only together with what keeps them from expanding.)

BODY, ENVIRONMENT, SYSTEM, COMPOSITION OF THE SYSTEM, STRUCTURE OF THE SYSTEM.
1. Give several examples of physical bodies missing in the textbook (no more than five).
2. What physical environments does a frog face in everyday life?
3. How do you think the physical body differs from the environment?

If you look into a sugar bowl or salt shaker, you will see that sugar and salt are made up of fairly small grains. And if you look at these grains through a magnifying glass, you can see that each of them is a polyhedron with flat edges (crystal). Without special equipment, we will not be able to distinguish what these crystals are made of, but modern science is well aware of methods that allow this to be done. These methods and the devices that use them were developed by physicists. They use very complex phenomena, which we will not consider here. We will only say that these methods can be likened to a very powerful microscope. If we look at a crystal of salt or sugar in such a "microscope" with greater and greater magnification, then, in the end, we will find that very small spherical particles are part of this crystal. Usually they are called atoms(although this is not entirely true, their more accurate name is nuclides). Atoms are part of all the bodies and environments around us.

Atoms are very small particles, their size ranges from one to five angstroms (denoted - A o .). One angstrom is 10-10 meters. The size of a sugar crystal is approximately 1 mm; such a crystal is approximately 10 million times larger than any of its constituent atoms. To better understand how small particles atoms are, consider this example: if an apple is enlarged to the size of the globe, then an atom, enlarged by the same amount, will become the size of an average apple.
Despite their small size, atoms are rather complex particles. You will get acquainted with the structure of atoms this year, but for now we will only say that any atom consists of atomic nucleus and related electron shell, which is also a system.
Just over a hundred types of atoms are currently known. Of these, about eighty are stable. And from these eighty types of atoms, all the objects around us are built in all their infinite variety.
One of the most important features of atoms is their tendency to combine with each other. Most often, this results in molecules.

A molecule can contain from two to several hundred thousand atoms. At the same time, small molecules (diatomic, triatomic ...) can also consist of identical atoms, while large ones, as a rule, consist of different atoms. Since a molecule consists of several atoms and these atoms are connected, the molecule is a system. In solids and liquids, molecules are connected to each other, but in gases they are not.
The bonds between atoms are called chemical bonds, and bonds between molecules intermolecular bonds.
Molecules linked together form substances.

Substances made up of molecules are called molecular substances. So, water is made up of water molecules, sugar is made up of sucrose molecules, and polyethylene is made up of polyethylene molecules.
In addition, many substances are composed directly of atoms or other particles and do not contain molecules in their composition. For example, aluminum, iron, diamond, glass, salt do not contain molecules. Such substances are called non-molecular.

In non-molecular substances, atoms and other chemical particles, as in molecules, are interconnected by chemical bonds. The division of substances into molecular and non-molecular is the classification of substances by building type.
Assuming that interconnected atoms retain a spherical shape, it is possible to construct three-dimensional models of molecules and non-molecular crystals. Examples of such models are shown in Figs. 1.1.
Most substances are usually found in one of three aggregate states: solid, liquid or gaseous. When heated or cooled, molecular substances can pass from one state of aggregation to another. Such transitions are schematically shown in Fig. 1.2.

The transition of a nonmolecular substance from one state of aggregation to another may be accompanied by a change in the type of structure. Most often, this phenomenon occurs during the evaporation of non-molecular substances.

At melting, boiling, condensation and similar phenomena that occur with molecular substances, the molecules of substances are not destroyed and are not formed. Only intermolecular bonds are broken or formed. For example, when ice melts, it turns into water, and when water boils, it turns into water vapour. Water molecules are not destroyed in this case, and, therefore, as a substance, water remains unchanged. Thus, in all three states of aggregation, this is the same substance - water.

But not all molecular substances can exist in all three states of aggregation. Many of them when heated decompose, that is, they are converted into other substances, while their molecules are destroyed. For example, cellulose (the main component of wood and paper) does not melt when heated, but decomposes. Its molecules are destroyed, and completely different molecules are formed from the "fragments".

So, the molecular substance remains itself, that is, chemically unchanged, as long as its molecules remain unchanged.

But you know that molecules are in constant motion. And the atoms that make up molecules also move (oscillate). As the temperature rises, the vibrations of atoms in molecules increase. Can we say that the molecules remain completely unchanged? Of course not! What then remains unchanged? The answer to this question is in one of the following paragraphs.

ATOM (NUCLIDE), MOLECULE, CHEMICAL BOND, INTERMOLECULAR BOND, MOLECULAR SUBSTANCE, NON-MOLECULAR SUBSTANCE, STRUCTURE TYPE, AGGREGATE STATE.

1. What bonds are stronger: chemical or intermolecular?
2. What is the difference between solid, liquid and gaseous states from each other? How do molecules move in gas, liquid and solid?
3. Have you ever observed the melting of any substances (except ice)? What about boiling (other than water)?
4. What are the features of these processes? Give examples of sublimation of solids known to you.
5. Give examples of substances known to you that can be a) in all three states of aggregation; b) only in solid or liquid state; c) only in the solid state.

As you already know, atoms are the same and different. How different atoms differ from each other in structure, you will soon learn, but for now we will only say that different atoms differ chemical behavior, that is, its ability to combine with each other, forming molecules (or non-molecular substances).

In other words, chemical elements are the very types of atoms that were mentioned in the previous paragraph.
Each chemical element has its own name, for example: hydrogen, carbon, iron, and so on. In addition, each element is also assigned its own symbol. You see these symbols, for example, in the "Table of Chemical Elements" in the school chemistry room.
A chemical element is an abstract collection. This is the name of any number of atoms of a given type, and these atoms can be anywhere, for example: one on Earth, and the other on Venus. A chemical element cannot be seen or felt by hand. The atoms that make up a chemical element may or may not be bonded to each other. Consequently, a chemical element is neither a substance nor a material system.

CHEMICAL ELEMENT, ELEMENT SYMBOL.
1. Give a definition of the concept of "chemical element" using the words "type of atoms".
2. How many meanings does the word "iron" have in chemistry? What are these values?

Before proceeding with the classification of any objects, it is necessary to choose the feature by which you will carry out this classification ( classification feature). For example, when putting a pile of pencils into boxes, you can be guided by their color, shape, length, hardness, or something else. The selected characteristic will be the classification feature. Substances are much more complex and diverse objects than pencils, so there are much more classification features here.
All substances (and you already know that matter is a system) are made up of particles. The first classification feature is the presence (or absence) of atomic nuclei in these particles. On this basis, all substances are divided into chemical substances and physical substances.

Such particles (and they are called chemical particles) can be atoms (particles with one nucleus), molecules (particles with several nuclei), non-molecular crystals (particles with many nuclei), and some others. Any chemical particle, in addition to nuclei or nuclei, also contains electrons.
In addition to chemicals, there are other substances in nature. For example: the substance of neutron stars, consisting of particles called neutrons; flows of electrons, neutrons and other particles. Such substances are called physical.

On Earth, you almost never encounter physical matter.
According to the type of chemical particles or the type of structure, all chemicals are divided into molecular and non-molecular, you already know that.
A substance can consist of chemical particles of the same composition and structure - in this case it is called clean, or individual substance. If the particles are different, then mixture.

This applies to both molecular and non-molecular substances. For example, the molecular substance "water" consists of water molecules of the same composition and structure, and the non-molecular substance "common salt" consists of salt crystals of the same composition and structure.
Most natural substances are mixtures. For example, air is a mixture of molecular substances "nitrogen" and "oxygen" with impurities of other gases, and rock "granite" is a mixture of non-molecular substances "quartz", "feldspar" and "mica" also with various impurities.
Individual chemicals are often referred to simply as substances.
Chemical substances can contain atoms of only one chemical element or atoms of different elements. On this basis, substances are divided into simple and complex.

For example, the simple substance "oxygen" consists of diatomic oxygen molecules, and the composition of the substance "oxygen" includes only atoms of the element oxygen. Another example: the simple substance "iron" consists of iron crystals, and the composition of the substance "iron" includes only atoms of the element iron. Historically, a simple substance usually has the same name as the element whose atoms are part of this substance.
However, some elements form not one, but several simple substances. For example, the element oxygen forms two simple substances: "oxygen", consisting of diatomic molecules, and "ozone", consisting of triatomic molecules. The element carbon forms two well-known non-molecular simple substances: diamond and graphite. Such a phenomenon is called allotropy.

These simple substances are called allotropic modifications. They are identical in quality composition, but differ from each other in structure.

Thus, the complex substance "water" consists of water molecules, which, in turn, consist of hydrogen and oxygen atoms. Therefore, hydrogen atoms and oxygen atoms are part of water. The complex substance "quartz" consists of quartz crystals, quartz crystals consist of silicon atoms and oxygen atoms, that is, silicon atoms and oxygen atoms are part of quartz. Of course, the composition of a complex substance can include atoms and more than two elements.
Compounds are also called compounds.
Examples of simple and complex substances, as well as their type of structure, are shown in Table 1.

Table I. Simple and complex substances molecular (m) and non-molecular (n / m) type of structure

On fig. 1.3 shows a classification scheme for substances according to the characteristics we have studied: by the presence of nuclei in the particles that form the substance, by the chemical identity of substances, by the content of atoms of one or more elements, and by the type of structure. The scheme is supplemented by dividing mixtures into mechanical mixtures and solutions, here the classification feature is the structural level at which the particles are mixed.

Like individual substances, solutions can be solid, liquid (commonly referred to simply as "solutions"), and gaseous (called mixtures of gases). Examples of solid solutions: gold-silver jewelry alloy, ruby ​​gemstone. Examples of liquid solutions are well known to you: for example, a solution of table salt in water, table vinegar (a solution of acetic acid in water). Examples of gaseous solutions: air, oxygen-helium mixtures for breathing scuba divers, etc.

CHEMICAL SUBSTANCE, INDIVIDUAL SUBSTANCE, MIXTURE, SIMPLE SUBSTANCE, COMPOUND SUBSTANCE, ALLOTROPY, SOLUTION.
1. Give at least three examples of individual substances and the same number of examples of mixtures.
2. What simple substances do you constantly encounter in life?
3. Which of the individual substances you gave as an example are simple substances, and which are complex?
4. In which of the following sentences are we talking about a chemical element, and which ones are about a simple substance?
a) An oxygen atom collided with a carbon atom.
b) Water contains hydrogen and oxygen.
c) A mixture of hydrogen and oxygen is explosive.
d) The most refractory metal is tungsten.
e) The pan is made of aluminum.
f) Quartz is a compound of silicon with oxygen.
g) An oxygen molecule consists of two oxygen atoms.
h) Copper, silver and gold have been known to people since ancient times.
5. Give five examples of solutions you know.
6. What, in your opinion, is the external difference between a mechanical mixture and a solution?

Each of the objects of the material system (except elementary particles) is itself a system, that is, it consists of other, smaller, objects interconnected. So, any system itself is a complex object, and almost all objects are systems. For example, a system important for chemistry - a molecule - consists of atoms linked by chemical bonds (you will learn about the nature of these bonds by studying Chapter 7). Another example: an atom. It is also a material system consisting of an atomic nucleus and electrons associated with it (you will learn about the nature of these bonds by studying Chapter 3).
Each object can be described or characterized in more or less detail, that is, list it characteristics.

In chemistry, objects are, first of all, substances. Chemicals are very diverse: liquid and solid, colorless and colored, light and heavy, active and inert, and so on. One substance differs from another in a number of ways, which, as you know, are called characteristics.

There are a wide variety of characteristics of substances: state of aggregation, color, smell, density, ability to melt, melting point, ability to decompose when heated, decomposition temperature, hygroscopicity (ability to absorb moisture), viscosity, ability to interact with other substances and many others. The most important of these features are compound and structure. It is on the composition and structure of a substance that all its other characteristics, including properties, depend.
Distinguish qualitative composition and quantitative composition substances.
To describe the qualitative composition of a substance, list the atoms of which elements are part of this substance.
When describing the quantitative composition of a molecular substance, the atoms of which elements and in what quantity form a molecule of a given substance.
When describing the quantitative composition of a non-molecular substance, the ratio of the number of atoms of each of the elements that make up this substance is indicated.
The structure of a substance is understood as a) the sequence of interconnection of the atoms that form this substance; b) the nature of the bonds between them; and c) the mutual arrangement of atoms in space.
Now let's return to the question that ended paragraph 1.2: what remains unchanged in molecules if the molecular substance remains itself? Now we can already answer this question: their composition and structure remain unchanged in molecules. And if so, then we can clarify the conclusion we made in paragraph 1.2:

A substance remains itself, that is, chemically unchanged, as long as the composition and structure of its molecules remain unchanged (for non-molecular substances - as long as its composition and the nature of the bonds between atoms are preserved ).

As for other systems, among the characteristics of substances in a special group are properties of substances, that is, their ability to change as a result of interaction with other bodies or substances, as well as as a result of the interaction of the constituent parts of a given substance.
The second case is quite rare, so the properties of a substance can be defined as the ability of this substance to change in a certain way under some external influence. And since external influences can be very diverse (heating, compression, immersion in water, mixing with another substance, etc.), they can also cause various changes. When heated, a solid can melt, or it can decompose without melting, turning into other substances. If a substance melts when heated, then we say that it has the ability to melt. This is a property of a given substance (it appears, for example, in silver and is absent in cellulose). Also, when heated, a liquid may boil, or it may not boil, but also decompose. This is the ability to boil (it manifests itself, for example, in water and is absent in molten polyethylene). A substance immersed in water may or may not dissolve in it, this property is the ability to dissolve in water. Paper brought to the fire ignites in air, but gold wire does not, that is, paper (or rather, cellulose) exhibits the ability to burn in air, and gold wire does not have this property. Substances have many different properties.
The ability to melt, the ability to boil, the ability to deform and the like properties refer to physical properties substances.

The ability to react with other substances, the ability to decompose, and sometimes the ability to dissolve, refers to chemical properties substances.

Another group of characteristics of substances - quantitative characteristics. Of the characteristics given at the beginning of the paragraph, density, melting point, decomposition temperature, and viscosity are quantitative. All of them represent physical quantities. In the course of physics, you got acquainted with physical quantities in the seventh grade and continue to study them. The most important physical quantities used in chemistry, you will study in detail this year.
Among the characteristics of a substance, there are those that are neither properties nor quantitative characteristics, but are of great importance in describing the substance. These include the composition, structure, state of aggregation and other characteristics.
Each individual substance has its own set of characteristics, and the quantitative characteristics of such a substance are constant. For example, pure water at normal pressure boils exactly at 100 o C, ethyl alcohol boils at 78 o C under the same conditions. Both water and ethyl alcohol are individual substances. And gasoline, for example, being a mixture of several substances, does not have a specific boiling point (it boils in a certain temperature range).

Differences in the physical properties and other characteristics of substances make it possible to separate mixtures consisting of them.

To separate mixtures into their constituent substances, various physical separation methods are used, for example: upholding with decantation(by draining the liquid from the sediment), filtration(straining), evaporation,magnetic separation(separation with a magnet) and many other methods. You will get to know some of these methods practically.

CHARACTERISTICS OF THE SUBSTANCE, QUALITATIVE COMPOSITION, QUANTITATIVE COMPOSITION, STRUCTURE OF THE SUBSTANCE, PROPERTIES OF THE SUBSTANCE, PHYSICAL PROPERTIES, CHEMICAL PROPERTIES.
1. Describe how the system
a) any object well known to you,
b) the solar system. Indicate the constituent parts of these systems and the nature of the connections between the constituent parts.
2. Give examples of systems consisting of the same components, but having a different structure
3. List as many characteristics as possible of some household item, for example, a pencil (as a system!). Which of these characteristics are properties?
4. What is a characteristic of a substance? Give examples.
5. What is a property of a substance? Give examples.
6. The following are sets of characteristics of three substances. All these substances are well known to you. Determine what substances are involved
a) A colorless solid with a density of 2.16 g / cm 3 forms transparent cubic crystals, odorless, soluble in water, an aqueous solution has a salty taste, melts when heated to 801 o C, and boils at 1465 o C, in moderate doses for humans is not toxic.
b) An orange-red solid with a density of 8.9 g / cm 3, the crystals are indistinguishable to the eye, the surface is shiny, it does not dissolve in water, it conducts electric current very well, it is plastic (it is easily drawn into a wire), melts at 1084 o C , and at 2540 o C boils, in the air it gradually becomes covered with a loose pale blue-green bloom.
c) Transparent colorless liquid with a pungent odor, density 1.05 g / cm 3, miscible with water in all respects, aqueous solutions have a sour taste, in dilute aqueous solutions it is not poisonous to humans, it is used as a seasoning for food, when cooled to - 17 o C solidifies, and when heated to 118 o C boils, corrodes many metals. 7. Which of the characteristics given in the previous three examples are a) physical properties, b) chemical properties, c) values ​​of physical quantities.
8. Make your own lists of characteristics of two more substances you know.
Separation of substances by filtration.

Everything that happens with the participation of physical objects is called natural phenomena. These include the transitions of substances from one state of aggregation to another, and the decomposition of substances when heated, and their interactions with each other.

During melting, boiling, sublimation, liquid flow, solid body bending and other similar phenomena, the molecules of substances do not change.

And what happens, for example, when burning sulfur?
During the combustion of sulfur, sulfur molecules and oxygen molecules change: they turn into sulfur dioxide molecules (see Fig. 1.4). Note that both the total number of atoms and the number of atoms of each of the elements remain unchanged.
Therefore, there are two types of natural phenomena:
1) phenomena in which the molecules of substances do not change - physical phenomena;
2) phenomena in which the molecules of substances change - chemical phenomena.
What happens to the substances during these phenomena?
In the first case, the molecules collide and fly apart without changing; in the second, the molecules, having collided, react with each other, while some molecules (old) are destroyed, and others (new) are formed.
What changes in molecules during chemical phenomena?
In molecules, atoms are bound by strong chemical bonds into a single particle (in non-molecular substances, into a single crystal). The nature of atoms in chemical phenomena does not change, that is, atoms do not turn into each other. The number of atoms of each element also does not change (atoms do not disappear and do not appear). What is changing? Bonds between atoms! Similarly, in non-molecular substances, chemical phenomena change the bonds between atoms. Changing bonds usually comes down to their breaking and the subsequent formation of new bonds. For example, when sulfur is burned in air, the bonds between sulfur atoms in sulfur molecules and between oxygen atoms in oxygen molecules are broken, and bonds are formed between sulfur and oxygen atoms in sulfur dioxide molecules.

The appearance of new substances is detected by the disappearance of the characteristics of the reacting substances and the appearance of new characteristics inherent in the reaction products. So, when sulfur is burned, yellow sulfur powder turns into a gas with a sharp unpleasant odor, and when phosphorus is burned, clouds of white smoke are formed, consisting of the smallest particles of phosphorus oxide.
So, chemical phenomena are accompanied by the breaking and formation of chemical bonds, therefore, chemistry as a science studies natural phenomena in which chemical bonds are broken and formed (chemical reactions), the physical phenomena accompanying them and, of course, the chemicals involved in these reactions.
To study chemical phenomena (that is, chemistry), you must first study the bonds between atoms (what they are, what they are, what are their features). But bonds are formed between atoms. Therefore, it is necessary first of all to study the atoms themselves, more precisely, the structure of atoms of different elements.
So in 8th and 9th grade you will learn
1) the structure of atoms;
2) chemical bonds and structure of substances;
3) chemical reactions and processes accompanying them;
4) properties of the most important simple substances and compounds.
In addition, during this time you will get acquainted with the most important physical quantities used in chemistry, and with the relationships between them, as well as learn how to perform basic chemical calculations.

M. V. Lomonosov

Take a look around you. What a variety of objects surrounds you: these are people, animals, trees. This is a TV, a car, an apple, a stone, a light bulb, a pencil, etc. It is impossible to list everything. In physics, any object is called physical body.

How are physical bodies different? Very many. For example, they can have different volumes and shapes. They can be made up of different substances. Silver and gold spoons have the same volume and shape. But they consist of different substances: silver and gold. Wooden cube and ball have different volume and shape. These are different physical bodies, but they are made of the same substance - wood.

In addition to physical bodies, there are also physical fields. The fields exist independently of us. They are not always detectable with the human senses. For example, the field around a magnet, the field around a charged body. But they are easy to detect with instruments.

Various changes can occur with physical bodies and fields. A spoon dipped in hot tea heats up. Water in a puddle evaporates and freezes on a cold day. The lamp emits light, the girl and the dog are running (moving). The magnet is demagnetized and its magnetic field is weakened. Heating, evaporation, freezing, radiation, movement, demagnetization, etc. - all these changes that occur with physical bodies and fields are called physical phenomena.

By studying physics, you will get acquainted with many physical phenomena.

To describe the properties of physical bodies and physical phenomena, we introduce physical quantities. For example, you can describe the properties of a wooden ball and cube using such physical quantities as volume, mass. A physical phenomenon - movement (of a girl, a car, etc.) - can be described knowing such physical quantities as path, speed, time interval. Pay attention to the main sign of a physical quantity: it can be measured using instruments or calculated using a formula. The volume of the body can be measured with a beaker of water, or you can measure the length a, width b and height c ruler, calculate by the formula

V = a ⋅ b ⋅ c.

All physical quantities have units of measurement. You have heard about some units of measurement many times: kilogram, meter, second, volt, ampere, kilowatt, etc. You will get acquainted with physical quantities in more detail in the process of studying physics, i.e. in the following articles.

In today's article, we will discuss what the physical body is. this term has already met you more than once during the years of schooling. We first encounter the concepts of "physical body", "substance", "phenomenon" in the lessons of natural history. They are the subject of study of most sections of the special science - physics.

According to "physical body" means a certain material object that has a form and a clearly defined outer boundary that separates it from the external environment and other bodies. In addition, the physical body has such characteristics as mass and volume. These parameters are basic. But there are others besides them. We are talking about transparency, density, elasticity, hardness, etc.

Physical bodies: examples

To put it simply, we can call any of the surrounding objects a physical body. The most familiar examples of them are a book, a table, a car, a ball, a cup. The physicist calls a simple body that whose geometric shape is simple. Composite physical bodies are those that exist in the form of combinations of simple bodies fastened together. For example, a very conditionally human figure can be represented as a set of cylinders and balls.

The material of which any of the bodies consists is called substance. At the same time, they can contain in their composition both one and a number of substances. Let's give examples. Physical bodies - cutlery (forks, spoons). They are usually made from steel. A knife can serve as an example of a body composed of two different kinds of substances - a steel blade and a wooden handle. And such a complex product as a cell phone is made from a much larger number of "ingredients".

What are the substances

They can be natural or artificially created. In ancient times, people made all the necessary items from natural materials (arrowheads - from clothes - from animal skins). With the development of technological progress, substances created by man appeared. And now they are in the majority. A classic example of a physical body of artificial origin is plastic. Each of its types was created by a person in order to ensure the necessary qualities of a particular object. For example, transparent plastic - for glasses lenses, non-toxic food - for dishes, durable - for car bumpers.

Any object (from to a high-tech device) has a number of certain qualities. One of the properties of physical bodies is their ability to attract each other as a result of gravitational interaction. It is measured using a physical quantity called mass. By definition of physicists, the mass of bodies is a measure of their gravity. It is denoted by the symbol m.

Mass measurement

This physical quantity, like any other, can be measured. To find out what is the mass of any object, you need to compare it with the standard. That is, with a body whose mass is taken as a unit. The international system of units (SI) is the kilogram. Such an "ideal" unit of mass exists in the form of a cylinder, which is an alloy of iridium and platinum. This international design is kept in France, and copies are available in almost every country.

In addition to kilograms, the concept of tons, grams or milligrams is used. Body weight is measured by weighing. This is a classic way for everyday calculations. But in modern physics there are others that are much more modern and highly accurate. With their help, the mass of microparticles, as well as giant objects, is determined.

Other properties of physical bodies

Shape, mass and volume are the most important characteristics. But there are other properties of physical bodies, each of which is important in a particular situation. For example, objects of equal volume can differ significantly in their mass, that is, have different densities. In many situations, characteristics such as brittleness, hardness, resilience or magnetic qualities are important. We should not forget about thermal conductivity, transparency, homogeneity, electrical conductivity and other numerous physical properties of bodies and substances.

In most cases, all such characteristics depend on the substances or materials of which the objects are composed. For example, rubber, glass and steel balls will have completely different sets of physical properties. This is important in situations where bodies interact with each other, for example, in studying the degree of their deformation when colliding.

About accepted approximations

Certain sections of physics consider the physical body as a kind of abstraction with ideal characteristics. For example, in mechanics, bodies are represented as material points that do not have mass and other properties. This branch of physics deals with the movement of such conditional points, and for solving the problems posed here, such quantities are of no fundamental importance.

In scientific calculations, the concept of an absolutely rigid body is often used. Such is conditionally considered a body that is not subject to any deformations, with no displacement of the center of mass. This simplified model makes it possible to theoretically reproduce a number of specific processes.

The section of thermodynamics for its own purposes uses the concept of a completely black body. What is it? A physical body (a certain abstract object) capable of absorbing any radiation falling on its surface. At the same time, if the task so requires, they can emit electromagnetic waves. If, according to the conditions of theoretical calculations, the shape of physical bodies is not fundamental, it is considered by default that it is spherical.

Why are the properties of bodies so important?

Physics itself, as such, originated from the need to comprehend the laws by which physical bodies behave, as well as the mechanisms for the existence of various external phenomena. Natural factors include any changes in our environment that are not related to the results of human activity. Many of them are used by people to their advantage, but others can be dangerous and even catastrophic.

The study of the behavior and various properties of physical bodies is necessary for people in order to predict adverse factors and prevent or reduce the harm they cause. For example, by building breakwaters, people are accustomed to dealing with the negative manifestations of the sea. Mankind has learned to resist earthquakes by developing special earthquake-resistant building structures. The load-bearing parts of the car are made in a special, carefully calibrated form to reduce damage in accidents.

About the structure of bodies

According to another definition, the term "physical body" means everything that can be recognized as really existing. Any of them necessarily occupies a part of space, and the substances of which they are composed are a collection of molecules of a certain structure. Its other, smaller particles are atoms, but each of them is not something indivisible and completely simple. The structure of an atom is rather complicated. In its composition, one can distinguish positively and negatively charged elementary particles - ions.

The structure, according to which such particles line up in a certain system, for solids is called crystalline. Any crystal has a certain, strictly fixed shape, which indicates the ordered movement and interaction of its molecules and atoms. When the structure of crystals changes, a violation of the physical properties of the body occurs. The state of aggregation, which can be solid, liquid or gaseous, depends on the degree of mobility of elementary components.

To characterize these complex phenomena, the concept of compression coefficients or volumetric elasticity, which are mutually reciprocal, is used.

Molecule movement

The state of rest is not inherent in either atoms or molecules of solids. They are in constant motion, the nature of which depends on the thermal state of the body, and the influences to which it is currently exposed. Part of the elementary particles - negatively charged ions (called electrons) moves at a higher speed than those with a positive charge.

From the point of view of the state of aggregation, physical bodies are solid objects, liquids or gases, which depends on the nature of molecular motion. The whole set of solids can be divided into crystalline and amorphous. The motion of particles in a crystal is recognized as completely ordered. In liquids, molecules move according to a completely different principle. They move from one group to another, which can be figuratively represented like comets wandering from one celestial system to another.

In any of the gaseous bodies, the molecules have a much weaker bond than in liquid or solid. Particles there can be called repulsive from each other. The elasticity of physical bodies is determined by a combination of two main quantities - the shear coefficient and the coefficient of volume elasticity.

Body fluidity

Despite all the significant differences between solid and liquid physical bodies, their properties have much in common. Some of them, called soft ones, occupy an intermediate state of aggregation between the first and second ones with physical properties inherent in both. Such a quality as fluidity can be found in a solid body (an example is ice or shoe pitch). It is also inherent in metals, including rather hard ones. Under pressure, most of them are able to flow like a liquid. By joining and heating two solid pieces of metal, it is possible to solder them into a single whole. Moreover, the soldering process takes place at a temperature much lower than the melting point of each of them.

This process is possible provided that both parts are in full contact. It is in this way that various metal alloys are obtained. The corresponding property is called diffusion.

About liquids and gases

Based on the results of numerous experiments, scientists have come to the following conclusion: solid physical bodies are not some isolated group. The difference between them and liquid ones is only in greater internal friction. The transition of substances to different states occurs under conditions of a certain temperature.

Gases differ from liquids and solids in that there is no increase in the elastic force even with a strong change in volume. The difference between liquids and solids is in the occurrence of elastic forces in solids during shear, that is, a change in shape. This phenomenon is not observed in liquids, which can take any of the forms.

Crystalline and amorphous

As already mentioned, two possible states of solids are amorphous and crystalline. Amorphous bodies are bodies that have the same physical properties in all directions. This quality is called isotropy. Examples include hardened resin, amber products, glass. Their isotropy is the result of the random arrangement of molecules and atoms in the composition of matter.

In the crystalline state, elementary particles are arranged in a strict order and exist in the form of an internal structure, periodically repeating in different directions. The physical properties of such bodies are different, but in parallel directions they coincide. This property inherent in crystals is called anisotropy. Its reason is the unequal force of interaction between molecules and atoms in different directions.

Mono- and polycrystals

In single crystals, the internal structure is homogeneous and repeats throughout the volume. Polycrystals look like a lot of small crystallites chaotically intergrown with each other. Their constituent particles are located at a strictly defined distance from each other and in the right order. A crystal lattice is understood as a set of nodes, that is, points that serve as centers of molecules or atoms. Metals with a crystalline structure serve as a material for the frames of bridges, buildings and other durable structures. That is why the properties of crystalline bodies are carefully studied for practical purposes.

Real strength characteristics are negatively affected by crystal lattice defects, both surface and internal. A separate section of physics, called solid body mechanics, is devoted to similar properties of solids.

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Physical body

Physical body is known to scientists in every detail, but we do not find in scientific research that unifying principle that would make it possible to put into a living connection with the entire Universe and turn into one harmonious whole all that mountain of heterogeneous research that scientists have piled up. Such unification is given to us by the occult teachings of Theosophy. In a short report, it is only possible to touch briefly on such a complex subject as the structure of the human body, and therefore we will say only a few words about the physical body, which is most familiar to everyone.

Western science is gradually beginning to lean towards accepting the theosophical view of man, according to which his organism consists of countless "infinitely small lives" that build his shells. The largest of these "lives" are known to physiology under the name of microbes, bacteria or bacilli, but among them the microscope managed to discover only giants, which, in comparison with other atomistic infinitesimal creatures, are the same as an elephant compared to ciliates.

Every physical cell is a living being animated by a ray prana", the life-force of the universe; the body of the cell is made up of molecules that are assimilated and then expelled, breathed in and expelled, while the soul of the cell is preserved, remains unchanged by this constant change of matter. These " infinitesimal lives They circulate through organic plexuses, penetrate cells and leave them with extraordinary speed, while being constantly affected by human psychic forces, which impregnate them with either evil or good influence.

We are constantly throwing out of ourselves millions of these "lives", which enter immediately into the surrounding kingdoms of nature, transferring there the energies that they have developed inside our organism. At the same time, they introduce into new organisms where they move, those properties that they received from us, from the mental forces of our organism, and thus they spread either rebirth or destruction, serve either to improve or damage the world around us.

The microbes that inhabit the human body can be referred to as molecular colonies; they are divided into "Creators" and "Destroyers". In our Aryan race, during the first 35 years of human life, the former predominate, and then the latter begin to predominate, as a result of which, at first, a slow, and then more and more rapid destruction of our body occurs.

The work of cells in our body, choosing from the blood what they need, is a purely physical consciousness. It takes place without any participation on the part of our human consciousness. " Unconscious memory”, as biologists call it, is the memory of precisely this, purely physical consciousness. We don't feel the same as the cells feel. The pain from the wound is felt by the brain consciousness, but the consciousness of the molecular aggregate, which we call the cell, makes it rush to restore damaged tissues, and this action of it remains outside the consciousness of the brain. The memory of the molecule causes it to repeat the same activity over and over again, even when the danger has passed: hence the scars on the wounds, scars, growths, etc.

The death of the physical body occurs when the removal from it of the physical energy that controls "infinitesimal lives”, gives these latter the opportunity to go each their own way. Then the "infinitely small lives", no longer connected with each other, fall apart and what we call decomposition sets in. The body becomes a cycle not controlled by anyone " infinitesimal lives”, and its form, which was the result of a planned relationship, is destroyed by an excess of their individual energy.

According to the book " Man and his visible and invisible composition"

Yoga Anatomy

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Azhna - the sixth chakra of man

sixth chakra located in the pituitary gland, behind the frontal bone. The chakra is called Azna' and translates as ' infinite power". sixth chakra- Centre intuition, inner voice and knowledge. A well developed talent for intuition leads us to people and places where we find the greatest personal expression of ourselves and opportunities for life and growth, both material and spiritual. It is the talent to be lucky and fearless, because we all "know" and trust the hand that guides us.

Anahata - the fourth chakra of man

fourth chakra located in the center of the chest, next to the thymus gland. Chakra called Anahata and translates as sound created without two objects touching and inaudible melody. It is our internal vibration that is reproduced as the energy of the solar plexus rises up and passes through the heart, creating a melody through our voice. Fourth chakra- the center of the expression of love, understanding, forgiveness, compassion and peaceful union of opposites in the mind.

human astral body

It is the third human body, after the physical and etheric bodies. astral matter penetrates the physical in such a way that every physical atom with its ethereal shell is separated from every other atom by an infinitely finer and more mobile astral matter. But this matter has completely different properties than physical matter, and it is invisible to us because we have not yet developed organs for perceiving it.

Aura - the eighth chakra of a person

Aura considered the eighth chakra in Kundalini yoga. This chakra is ours aura, or energy that can be felt and even seen by some around us. This is our electromagnetic field. When our aura strengthened and there are no gaps in it, a natural radiance emanates from us, which manifests itself through a smile, the sparkle of the eyes, the clarity of the gaze, the clarity of thoughts and self-expression. You are a beacon for others, this is perhaps the easiest way to describe a strong aura.

Vedic Knowledge Ayurveda and Yoga

Ayurveda is only a small part of the vast Vedic knowledge. Knowledge of Ayurveda is very relevant in the practice of the external sections of yoga - asanas and pranayamas, which are given special attention in hatha yoga, since they, like Ayurveda, are aimed at harmonizing and cleansing the body. This system reflects the natural desire of all living things to restore unity with the divine source.