What is the concept of “energy” that we use so often? “Energy” (Greek ενεργια - action, activity) - a general quantitative measure various forms movement of matter. By and large, the concept of energy, the idea of ​​energy, is artificial and created specifically to be the result of our thoughts about the world around us. Unlike matter, about which we can say that it exists, energy is the fruit of human thought, his “invention”, built in such a way as to be able to describe various changes in the surrounding world and at the same time talk about the constancy, conservation of which -what was called energy. For this physical quantity for a long time the term “living force” was used, introduced by I. Newton. For the first time in history, Robert Mayer puts into the concept of “living force” the meaning of “energy”, without even uttering this word, in the article “Remarks on Forces.” inanimate nature", published in 1842. The special term “energy” was introduced in 1807 by the English physicist Thomas Young and denoted a quantity proportional to the mass and square of the speed of a moving body. The term “energy” in its modern sense was introduced into science by William Thomson (Lord Kelvin) in 1860.

Energy manifests itself in various forms of movement of matter that fills all cosmic space. A property inherent in all types of energy and uniting them is the ability of each type of energy to transform, under certain conditions, into any other type in a strictly defined quantitative ratio. The very name of this property - “the law of conservation and transformation of energy” - was introduced into scientific circulation by F. Engels, which made it possible to measure all types of energy in the same units. The joule is taken as such a unit (1 J = 1 H m = 1 kg m 2 / s 2). At the same time, to measure the amount of heat, the “old” unit is used - 1 cal (calorie), to measure mechanical energy - the value of 1 kgm = 9.8 J, electrical energy - 1 kW h = 3.6 MJ, while 1 J = 1 W s.

Almost all types of energy considered in technical thermodynamics, with the exception of heat, represent the energy of directed motion. Thus, mechanical energy manifests itself in the directly observable movement of bodies, which has a certain direction in space (movement of gas through a pipe, flight of a projectile, rotation of a shaft, etc.). Electrical energy manifests itself in the latent movement of electrons along a conductor ( electricity). Thermal energy is expressed in molecular and intramolecular chaotic motion, representing the energy of the chaotic movement of atoms and molecules of a substance. The thermal energy of gases manifests itself in the vibrational, rotational and translational motion of molecules, which constantly change their speed in magnitude and direction. In this case, each molecule can move randomly throughout the entire volume of the gas. IN solids thermal energy manifests itself in vibrations of molecules and atoms relative to positions determined by the crystal structure of a substance; in liquids, in vibrations and movement of molecules or their complexes. Consequently, the fundamental difference between thermal energy and other types of energy is that it is the energy of chaotic rather than directed motion. As a result of this, the transformation of thermal energy into any type of energy of directed motion has its own characteristics, the study of which is one of the main tasks of technical thermodynamics.

Each body in any state can simultaneously possess different types of energy, including thermal, mechanical, electrical, chemical, intranuclear, as well as potential energy of various physical fields (gravitational, magnetic, electric). The sum of all the types of energy a body possesses is its total energy.

Thermal, chemical and intranuclear energies are included in internal energy bodies. All other types of energy associated with the movement of a body, as well as the potential energy of external physical fields, belong to its external energy. For example, the external energy of a flying projectile in the zone of action of the forces of gravity will be the sum of its kinetic E k and potential energy gravitational field E p.g. If a gas or liquid moves in a continuous flow in a pipe, then their external energy additionally includes pushing energy, sometimes called pressure energy E etc .

The external energy is therefore the sum

E in n = E k + Σ E p i + E p r, where E p i is the potential energy of the i-th field (magnetic, electrostatic, etc.).

The internal energy of a body U can be represented as consisting of two parts: the internal thermal energy U T and U 0 - the internal zero energy of the body, conditionally cooled to absolute zero temperatures:

U=U 0 +U T .

Internal thermal energy is that part of the total internal energy of the body that is associated with thermal chaotic movement molecules and atoms and can be expressed through body temperature and other parameters. Since the temperature of a real body only partially reflects its internal thermal energy, a change in the latter can also occur at constant body temperature. Examples of this are the processes of evaporation, melting, sublimation, in which a phase transformation occurs and the degree of randomness of molecular motion changes.

Thus, the total energy of a body in the general case can be presented as the sum of internal zero U 0 , internal thermal U T , external kinetic E k energies, total external potential Σ E p i energies and pushing energy E p : E = U 0 +U T +E k + Σ E p i +E p r .

Each of these components total energy can, under certain conditions, transform into one another. For example, in chemical reactions there is a mutual conversion of U 0 to U T . If the reaction is exothermic, then part of the zero energy is converted into heat. The zero-point energy of the resulting substances turns out to be less than the initial ones - “heat release” occurs. In endothermic reactions, the opposite phenomenon is observed: zero energy increases due to a decrease in thermal energy - “heat absorption” occurs.

In processes not related to change chemical composition substances, zero-point energy does not change and remains constant. Under these conditions, only the internal thermal energy changes. This allows us to take into account in various calculation equations only the change in internal thermal energy, which we will further call simply internal energy U. If a homogeneous body of mass m has internal energy U, then the internal energy of 1 kg of this body is u=U/m.

The magnitude is called specific internal energy and measured in J/kg.

External kinetic energy (J) is the energy of translational motion of the body as a whole and is expressed by the formula

E к =mw 2 /2, where m – body weight, kg; w – speed of movement, m/s.

External potential energy as the energy of the directed action of static fields can be expressed in terms of the possible work of each field from a given position to some zero. Thus, the potential energy of a gravitational field is expressed as the product of the force of gravity mg of this body and its height H above any reference zero:

Here the height H represents the corresponding coordinate.

The pushing energy E p is the additional energy of a substance that arises in the system due to the influence of other parts of the system on it, trying to push this substance out of the occupied vessel. Thus, when a gas (or steam) flows through a pipe or any channel under continuous flow conditions, each kilogram of this gas, in addition to internal and external kinetic and potential energies, has additional pushing energy carried by itself:

E pr . =p υ ,

where p – specific pressure; υ – specific volume (volume of 1 kg of substance mass).

For gases, vapors and liquids in a flow, the value p υ (or pV for m kg of substance) determines their integral part

energy. Therefore, for substances in a continuous flow, the determining parameter will no longer be the internal energy U, but the sum U+pV=I, called enthalpy. For 1 kg of substance i =u+ p υ, where i is in J/kg.

The same energy i is possessed by 1 kg of gas located in the cylinder when it is displaced by the piston.

The total energy of the system under consideration, consisting of 1 kg of gas and a piston acting on it, will be equal to the sum of the internal energy of the gas and the energy p υ of its expulsion, i.e., equal to its enthalpy. For this reason, enthalpy is often called energy of the expanded system.

In order for any organism to begin to function, it must be fed. And for the mechanism to start working, it must be supplied with fuel or connected to electricity. What does all this have in common? Food, gasoline, electricity - energy sources.

Energy- a source of motion that helps to do work.

Energy can exist in a free state, for example in the form of sunlight or heat. But energy can be contained in matter. So, thermal energy, stored in firewood, is released during combustion and does work - it warms the room.

Remember how the wood burns in the stove and how the kettle heats up. This is work thermal energy.

A person uses different types of energy. Previously, ancient people used the energy accumulated in the bodies of themselves and their domestic animals to perform work. Over time, they mastered the ability to receive heat, that is, to use the thermal energy contained in the firewood.

When wood supplies began to decline, people learned to use the energy contained in coal mined from underground storehouses. A steam engine was invented, in which steam energy drove the wheels of a steam locomotive and steamship.

Time passed. People have discovered others energy sources. From oil they began to obtain kerosene and gasoline, which serve fuel for modern engines. Today, this fuel powers cars, diesel locomotives, ships and airplanes. Material from the site

Thanks to scientific discoveries people have learned to use electrical energy. We can no longer imagine our life without her. The energy of electricity lit light bulbs in houses, made vacuum cleaners, mixers, radios and televisions work. It powered the engines of electric locomotives and electric trains.

Even from atoms - the smallest particles of matter - people have learned to extract energy. She was named atomic energy.

On this page there is material on the following topics:

• Topic of the lesson: types of energy, natural history

• Energy types of energy briefly

• Energy in human life short abstract

• Energy short report on physics

• Types and sources of energy in brief

Questions about this material:

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Permanent magnets, although they have a reserve of energy, give it away very reluctantly, so there is no need to specifically name this energy. However, electric current creates extended, strong magnetic fields. As soon as the current is turned off, the magnetic field...

01 08 2016

The most common one we encounter in Everyday life– mechanical energy. This is the energy of direct interaction and movement of physical bodies and their parts. Within the framework of Mechanics (section of Physics), mechanical energy is divided into potential energy (for things at rest...

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Light energy is familiar to all people of all times from birth. Since ancient times, such sources of light energy as the Sun, Moon and Stars, fire, torch, chemiluminescent animals and plants have been known. Currently, the Sun continues to be the main and...

25 07 2016

Is it cold or hot in our world? At first glance, the matter of the Universe is not that hot. We breathe cool air, drink cold water, skate on ice, make snowballs. The black night sky does not warm us. To keep warm, you have to light fires and stoke stoves. Meanwhile...

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Chemical energy is known to everyone to modern man and is widely used in all fields of activity. It has been known to Mankind since ancient times and has always been used both in everyday life and in production. The most common devices using...

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In many cases, electrical and magnetic energies are closely related to each other, each of them can be considered as the “flip side” of the other. Alternating currents are created by variables electric fields and form alternating magnetic fields around themselves. During...

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The energy carried by the wave can be enormous. An example of this is the World Ocean. When the calm, gently licking surface of the shore turns into a storm, sea waves are capable of destroying ships, throwing huge stones ashore, splashing water into highly elevated reservoirs,...

Types of energy - types of energy known to mankind

The concept of “energy” is defined as a measure of various forms of motion of matter and as a measure of the transition of the motion of matter from one form to another. Accordingly, types and types of energy are distinguished according to the forms of motion of matter. The man deals with different types of energy. In fact, the entire technological process is the transformation of one type of energy into another. During the passage of the technological path, energy is repeatedly converted from one type to another, which leads to a decrease in its useful amount due to losses and dissipation in the environment.

Types of energy known today

• Mechanical
• Electric
• Chemical
• Thermal
• Light (Radiant)
• Nuclear (Atomic)
• Thermonuclear (Fusion)

In addition, we know other types of energy, the names of which have a descriptive rather than a physical meaning, such as wind energy, or geothermal energy. In such cases, the physical form of the nature of the energy is replaced by the name of its source. Therefore, it is more correct to speak about the mechanical energy of the wind, the energy of the wind flow, or the thermal energy of geothermal sources. Otherwise, the number of pseudo energies can be multiplied indefinitely, inventing garbage energy, hydrogen energy, mental energy, or vital energy, and hand energy. By combining the word “energy” with specific objects, we deprive this connection physical meaning. It is impossible to measure the amount of psychic energy, or will energy. All that remains is a hint that the object has some kind of energy, but we don’t know what kind. It turns out that the text or speech is littered with a word that does not carry a semantic load, because every object carries energy and it is pointless to mention it. And by analogy with the energy of thought, the mass of thought, the length, width and height of thought, as well as its density, should appear. In short, such phrases are obvious evidence of the stupidity and illiteracy of the author or speaker.

Physical concepts related to the definition of the word “energy”

But let’s return to the real physical concepts associated with the definition of the word “energy”. The above listed types of energy are known to man and have been used by him throughout the history of civilization. The only exception is the energy of atomic decay, obtained only at the beginning of the 20th century. Thus, we still use mechanical energy today when riding a bicycle, using pendulum clocks, or lifting and lowering loads with a crane. Electrical energy has been familiar to us since ancient times in the form of lightning and static electricity. However, this type of energy began to be widely used only in the 19th century, when the Voltaic column was invented - a direct current battery and. However, even in ancient times, people knew and used this type of energy, although not everywhere. There are known ancient Egyptian jewelry and objects of worship, the coating of which could only be done by electrolysis. - perhaps the most common and widely used type of energy, both in ancient times and in our days. A fire, coals, a burner, matches and many other objects associated with combustion are based on the energy of the chemical interaction of organic matter and oxygen. Today, high-tech “combustion” is carried out in and, in and. However, devices such as turbines and internal combustion engines have a bad intermediary between the raw material (chemical energy) and the final product (electrical energy). Unfortunately, the efficiency of heat engines is small, and the limitations are imposed not by the material, but by the theory. For the limit is 40%. Human bodies and all animals operate on the basis of chemical interactions, chemical energy. By eating plants, we get energy from them chemical bonds formed due to the absorption of solar energy. That is, indirectly, a person also feeds on solar energy, just as all living things on Earth feed on it. The sun is the energy without which there would be no life on our planet. Almost all types and types of energy, except atomic and thermonuclear, can be considered secondary in relation to radiant solar energy. The mechanical energy of the tides, as well as the thermal energy of geothermal sources, are also not associated with solar radiation.

Thermonuclear energy underlies the work of our central luminary - the Sun

This means that solar energy, in turn, is a product of thermonuclear fusion energy released in the depths of the Sun. Thus, the vast majority of the types of energy we use on Earth have their primary progenitor in the form of thermonuclear fusion energy. Nuclear, or atomic Energy– the only type of energy that falls outside the “standard” natural energy cycle. Before the advent of man, nature did not know (with rare exceptions) the processes of mass point decay atomic nuclei with the release of enormous energy. The exception is the African natural “atomic reactor” - a deposit of uranium ores, where atomic decay reactions occur with heating of the surrounding rocks. However, in nature, atomic decay lasts millions of years, because the half-lives of uranium and plutonium are very long. And although many other atoms, in addition to uranium and plutonium, are also subject to atomic decay, in general, these processes do not cause significant changes in the surrounding matter per unit time. Man has made changes to the energy balance of the planet by exploding bombs, building nuclear power plants, burning oil, gas and coal. Of course, similar processes occurred before humans, but they were extended over millions of years. Meteorites fell, forests burned, carbon dioxide was released from swamps and the thickness of the world's oceans, and uranium decayed. But slowly - in small volumes per unit of time.

Alternative sources

Today, alternative types of energy and alternative ones are actively developing. However, these very words already contain an erroneous attitude towards the word “energy”. By calling energy sources “alternative” we contrast them with “traditional” sources - coal, oil and gas. And this is understandable. But when we say “alternative energy” we are talking nonsense, because different kinds energies exist outside of our desires. And it is not clear what the alternative is to wind energy, because it simply exists. Or what is the alternative to solar and thermonuclear energy of our star. In any case, we use it, and it is strange to call it alternative, since there are no alternatives for it. In the next thousands of years, we will not go anywhere from using solar energy, since the entire ecosystem of the planet is based on it. The words “non-traditional types of energy”, “renewable types of energy”, or “environmentally friendly types of energy” look similarly strange. What type of energy is traditional? How can one or another type of energy be renewed? How to check energy for environmental cleanliness? “Traditionality”, “renewability” and “environmental friendliness” are more reasonable and correct to refer to. Then everything will immediately become clear and understandable. And then, having sorted the cause-and-effect relationships, you can begin the search. Non-traditional types of energy sources can be easily found by studying nature and the world. Here you will find manure for heating, hay, and a generator that uses muscle power.

Renewable energy sources should be sought only in the environment of natural processes

There are not so many similar processes and they are all associated with the movement of matter around the planet - earth, water, air, as well as with the activities of living organisms. Although, strictly speaking, there are no renewable energy sources, since our main “battery” - the Sun - has a limited service life. And to search for environmentally friendly sources, you must first clearly define the criteria for environmental friendliness, because, in fact, any human intervention in the energy balance of the planet causes damage to the environment. Strictly speaking, there cannot be environmentally friendly energy sources, because in any case they will affect the environment. We can only reduce this influence to a minimum, or compensate for it. In this case, any compensatory effects must be carried out within the framework of a global analytical forecast model.

These are all different types of energy. All processes occurring in nature require energy. In any process, one type of energy is converted into another. Food products – potatoes, bread, etc. - These are energy storage facilities. We get almost all the energy we use on Earth from the Sun. transfers to the Earth as much energy as would be produced by 100 million powerful power plants.

Types of energy

Energy exists in the most different types. In addition to thermal, light and sound energy, there is also chemical energy, kinetic and potential. An electric light bulb emits heat and light energy. Sound energy is transmitted using waves. The waves cause the eardrums to vibrate, which is why we hear sounds. Chemical energy is released through chemical reactions. Food, fuel (coal, oil, gasoline), and batteries are storage facilities for chemical energy. Food products are stores of chemical energy released within the body.

Moving bodies have kinetic energy, i.e. energy of movement. The faster a body moves, the greater its kinetic energy. Losing speed, the body loses kinetic energy. When hitting a stationary object, a moving body transfers part of its kinetic energy to it and sets it in motion. Animals convert some of the energy they receive from food into kinetic energy.

Bodies located in a force field, such as a gravitational or magnetic field, have potential energy. Elastic or elastic bodies (having the ability to stretch) have potential energy tension or elasticity. A pendulum has maximum potential energy when it is at its highest point. By unfolding, the spring releases its potential energy and causes the wheels in the clock to rotate. Plants receive energy from the Sun and produce nutrients - creating reserves of chemical energy.

Conversion of energy

The law of conservation of energy says that energy is neither created from nothing nor lost without a trace. In all processes occurring in nature, one type of energy is converted into another. The chemical energy of the flashlight batteries is converted into electrical energy. In a light bulb Electric Energy turns into heat and light. We have given an example of this “energy chain” to show you how one type of energy is converted into another.

Coal is the compressed remains of plants that lived many years ago. They once received energy from the Sun. Coal is a store of chemical energy. When coal burns, its chemical energy is converted into thermal energy. Thermal energy heats the water and it evaporates. The steam turns the turbine. thereby producing kinetic energy - the energy of motion. The generator converts kinetic energy into electrical energy. A variety of devices - lamps, televisions, heaters, tape recorders - consume electricity and convert it into sound, light and heat.

The end results in many energy conversion processes are light and heat. Although the energy does not disappear, it goes into space and is difficult to capture and use.

Solar energy

Energy from the Sun reaches the Earth in the form electromagnetic waves. This is the only way energy can be transmitted through outer space. It can be used to create electricity using photovoltaic cells or to heat water in solar collectors. The collector panel absorbs thermal energy from the Sun. The figure shows a cross-section of the collector panel. The black panel absorbs the thermal energy coming from the Sun and heats up in the pipes. This is how the roof of a house heated by the Sun is constructed. Solar energy is transferred to water used for domestic needs and heating. Excess heat enters the energy storage facility. Energy is conserved using chemical reactions.

Energetic resources

We need energy to light and heat our homes, to cook food, so that factories can operate and cars can move. This energy is generated by the combustion of fuel. There are other ways to obtain energy - for example, it is produced hydroelectric power stations. Almost half of the world's population burns wood, manure or coal to cook food and heat their homes.

Wood, coal, oil and natural gas are called non-renewable resources, since they are used only once. Sun, wind, water - it's renewable energy resources, since they themselves do not disappear during energy production. In their activities, humans use fossil resources for energy production - 77%, wood - 11%, renewable energy resources - 5% and nuclear energy - 3%. We call coal, oil and natural gas fossil fuels, since we extract them from the depths. They were formed from the remains of plants and animals. Almost 20% of the energy we use comes from coal. When fuel burns, they get into carbon dioxide and other gases. This is partly the reason for such phenomena as acid rain and the greenhouse effect. Only about 5 percent of energy comes from renewable sources. This is the energy of the Sun, water and wind. Another renewable source of energy is gas produced during decay. When organic matter rot and release gases, in particular methane. Natural gas is mainly made up of natural gas, which is used to heat homes and water. For several millennia, people have used wind energy to propel sailing ships and turn windmills. Wind can also produce electricity and pump water.

Energy and power units

To measure the amount of energy, a special unit is used - the joule (J). One thousand joules equals one kilojoule (kJ). An ordinary apple (about 100 g) contains 150 kJ of chemical energy. 100 g of chocolate contains 2335 kJ. Power is the amount of energy used per unit of time. Power is measured in watts (W). One watt is equal to one joule per second. The more energy a particular mechanism produces over a certain time, the greater its power. A 60 W light bulb uses 60 J per second, and a 100 W light bulb uses 100 J per second.

Efficiency

Any mechanism consumes energy of one type (for example, electrical) and converts it into energy of another type. The greater the efficiency of the mechanism most of energy consumed is converted into required energy. The efficiency of almost all cars is low. The average car converts only 15% of the chemical energy in gasoline into kinetic energy. All remaining energy turns into heat. Fluorescent lamps are more efficient than conventional light bulbs because fluorescent lamps convert more electricity into light and less into heat.