Beneficial and harmful effects of resonance in a car. Resonance: in simple words

Fedotova Victoria

Purpose: To study information about mechanical resonance, its application and accounting.

Objectives: 1. Collect and systematize information on the use and accounting of mechanical resonance in nature, everyday life and technology.

2. Demonstrate experiments to observe mechanical resonance.

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Mechanical resonance

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Mechanical resonance benefit harm

On January 20 (February 2), 1905, a squadron of guards cavalry passed across the Egyptian Chain Bridge in St. Petersburg

Destruction of the Tacoma Bridge in America in 1940

In 2010, a bridge in Volgograd “danced”

Resonance in technology 1. 2. 3. 4.

Trumpets of Jericho

The oral and nasal cavities act as resonators

Frequency meter

Sound resonance

Mechanical resonance benefit harm P apply Take into account and reduce

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Physics project “Mechanical resonance”

Purpose: To study information about mechanical resonance, its application and accounting.

Objectives: 1. Collect and systematize information on the use and accounting of mechanical resonance in nature, everyday life and technology.

2. Demonstrate experiments to observe mechanical resonance.

Each of us loves a fun activity - swinging on a swing. When entertaining ourselves or a child, we apply force in the desired direction at a strictly defined moment. A person who tries to rock a swing by pushing it at the wrong time would look very strange. Why is it impossible to swing a swing if you apply force at the wrong time? This question remained unanswered for a long time until we studied resonance in physics class. This natural phenomenon is very mysterious. We decided to lift the veil of secrecy a little.

Mechanical resonanceis the phenomenon of a sharp increase in the amplitude of oscillations when the frequency of forced oscillations coincides with the natural frequency of the physical system.Resonance phenomenon was first described Galileo Galilei in 1602 in works devoted to the studypendulums and musical strings.Resonance is most clearly observed if friction in the system is minimal.

To prevent this phenomenon, either increase friction or change the parameters of the oscillatory system itself.

Like any natural phenomenon, resonance cannot be uniquely beneficial or harmful; it has its pros and cons. When it is harmful, they take it into account and try to prevent it; if it is useful, they use it.

Each part, mechanism, machine or building has its own vibration frequency. If they come under the influence of a driving force during operation, the consequences can be very dangerous if the frequencies coincide.

On January 20 (February 2), 1905, a squadron of guards cavalry passed across the Egyptian Chain Bridge in St. Petersburg, 11 sleighs with drivers were moving towards it. At that moment, the bridge collapsed onto the ice of the Fontanka. The main version is that the bridge structure could not withstand too rhythmic vibrations from the coordinated step of the military, which is why a resonance occurred in it. This version was included in the school physics curriculum as an illustrative example, in addition, a new military command was introduced to “go out of step”, it is given to a combat column before entering any bridge. The destruction of the Tacoma Bridge occurred due to the same resonance in America in 1940, the bridge in Angers, in France in 1850. In 2010, a bridge in Volgograd “danced”.

Mechanical resonance can occur, for example, during the acceleration of the rotor of a mechanism at some intermediate speed; As the frequency increases, the resonance stops. Resonance may not occur in the entire mechanism, but only in some part of it; If it resonates, it may break off.

Some test pilots reported with horror that during flight their plane suddenly began to shake violently, and after a few minutes it literally disintegrated in the air. Investigations of such cases provided an answer about the culprit of the accident: it was a resonance. When the engines were operating, their oscillation frequencies coincided with the natural oscillation frequency of the aircraft body. The range of vibrations kept increasing, and the plane simply disintegrated in the air. There are cases where ocean liners had to be rebuilt to reduce vibration. Any body has its own vibration frequency. And if you manage to select the same frequency of the external force, destruction will be inevitable. The clearest example of this is the Trumpets of Jericho. According to legend, when they blew the trumpet, the walls of Jericho collapsed. You can break a glass in the same way. And Shrek lovers remembered the bird that burst due to Fiona’s singing. The response, called resonance, manifests itself in this way. Here the window glass hummed and vibrated without any impacts or other noticeable influences; but when listening to soft music, the glass standing in the closet began to respond, and on the same note.

Let us transport ourselves mentally to ancient Rome, where various tragedies were played on the stage of the Colosseum. The huge amphitheater is designed in such a way that everyone present can hear even a whisper spoken word on stage. This is where resonance works. After all, modern concert halls are built according to special laws, creating conditions for resonance. Yes, and you and I use it to communicate. When speaking or singing, we round our mouth, increasing the sound. Howler monkeys take advantage of this phenomenon much better than us; their roars can be heard for several kilometers. And ordinary frogs make quite loud calls during the mating season. Both have a resonator sac, which they inflate when they scream. People noticed the phenomenon of resonance in nature and began to use it for their own purposes. Many of us have repeatedly admired the elegant forms of musical instruments, but only a few ask themselves the question: “Why does a violin need such a shape?” And it's all about resonance. Sounds of different heights resonate in different places of the intricately curved instrument. All audio amplifiers are sized for resonance. As soon as you change them a little, the sound immediately “disappears”. The noise of a sea shell is also generated by resonance.

The action of a device that allows you to measure the frequency of oscillations is based on the phenomenon of resonance. This device is called frequency meter. The frequency of mechanical vibrations is usually measured using vibration mechanical and electrical frequency counters ., used in conjunction with converters of mechanical vibrations into electrical ones. The simplest vibration mechanical frequency meter, the action of which is based on resonance, is a series of elastic plates reinforced at one end on a common base. The plates are selected according to length and weight so that the frequencies of their own vibrations form a certain discrete scale, on which the value of the measured frequency is determined. Mechanical vibrations acting on the base frequency meter , cause vibration of the elastic plates, with the greatest amplitude of vibrations observed in the plate whose natural frequency is equal (or close in value) to the measured frequency.

Experiments to observe resonance.

1. Let's hang several pendulums of different lengths from a rope fixed in the racks. Let's deflect the pendulum A from the equilibrium position and leave it to itself. It will oscillate freely, acting with some periodic force on the rope. The rope, in turn, will act on the remaining pendulums. As a result, all pendulums will begin to perform forced oscillations with the frequency of oscillations of the pendulum A . We will see that all pendulums will begin to oscillate with a frequency equal to the frequency of the pendulum's oscillations A . However, their amplitude of oscillations, except for the pendulum C , will be less than the amplitude of the pendulum oscillations A. Pendulum C , the length of which is equal to the length of the pendulum A , will swing very strongly. Consequently, the pendulum has the greatest oscillation amplitude, the natural frequency of oscillations of which coincides with the frequency of the driving force. In this case they say that it is observed resonance
2. Let's place two identical tuning forks side by side, turning them towards each other on those sides of the boxes where there are no walls. Let's hit the left tuning fork with a hammer. In a second we'll drown it out with our hands. We will hear the sound of the second tuning fork, which we did not hit. They say that the right tuning fork resonates, that is, it captures the energy of sound waves from the left tuning fork, as a result of which it increases the amplitude of its own vibrations.

Conclusion: Having studied the phenomenon of mechanical resonance, it became clear that this is a complex phenomenon. It must be remembered and taken into account, as it can bring benefit and harm. If resonance is beneficial, then it is used and applied, and if it is harmful, then it is taken into account and the effect of resonance is reduced.

From the course of study at school and institute, many learned the definition of resonance as the phenomenon of a gradual or sharp increase in the amplitude of vibrations of a certain body when an external force is applied to it with a certain frequency. However, few can answer the question of what resonance is with practical examples.

Physical definition and binding to objects

Resonance, by definition, can be understood as A fairly simple process:

• there is a body that is at rest or oscillates with a certain frequency and amplitude;
• it is acted upon by an external force with its own frequency;
• in the case when the frequency of the external influence coincides with the natural frequency of the body in question, a gradual or sharp increase in the amplitude of oscillations occurs.

However, in practice the phenomenon is considered as a much more complex system. In particular, the body can be represented not as a single object, but as a complex structure. Resonance occurs when the frequency of the external force coincides with the so-called total effective oscillatory frequency of the system.

Resonance, if we consider it from the standpoint of its physical definition, must certainly lead to the destruction of the object. However, in practice there is a concept of the quality factor of an oscillatory system. Depending on its value, resonance can lead to various effects:

• with a low quality factor, the system is not able to retain oscillations coming from outside to a large extent. Therefore, there is a gradual increase in the amplitude of natural vibrations to a level where the resistance of materials or connections does not lead to a stable state;
• high quality factor, close to unity, is the most dangerous environment in which resonance often leads to irreversible consequences. These may include both mechanical destruction of objects and the release of large amounts of heat at levels that can lead to fire.

Also, resonance occurs not only under the action of an external force of an oscillatory nature. The degree and nature of the system's response is, to a large extent, responsible for the consequences of externally directed forces. Therefore, resonance can occur in a variety of cases.

A textbook example

The most common example used to describe the phenomenon of resonance is the case when a company of soldiers walked along a bridge and collapsed it. From a physical point of view, there is nothing supernatural in this phenomenon. Walking in step, soldiers caused hesitation, which coincided with the natural effective oscillatory frequency of the bridge system.

Many people laughed at this example, considering the phenomenon only theoretically possible. But advances in technology have proven the theory.

There is a real video online of the behavior of a pedestrian bridge in New York, which constantly swayed violently and almost collapsed. The author of the creation, which with its own mechanics confirms the theory when resonance arises from the movement of people, even chaotic ones, is a French architect, author of the Millau Viaduct suspension bridge, a structure with the highest supporting columns.

The engineer had to spend a lot of time and money to reduce the quality factor of the system footbridge to an acceptable level and ensure that there are no significant vibrations. An example of the work on this project is an illustration of how the effects of resonance can be curbed in low-Q systems.

Examples that are repeated by many

Another example, which is even included in jokes, is the breaking of dishes by sound vibrations, from practicing the violin and even singing. Unlike a company of soldiers, this example was repeatedly observed and even specially tested. Indeed, the resonance that occurs when the frequencies coincide leads to the splitting of plates, glasses, cups and other utensils.

This is an example of process development under conditions of a high-quality system. The materials from which the dishes are made are sufficiently elastic media, in which the oscillations propagate with low attenuation. The quality factor of such systems is very high, and although the frequency coincidence band is quite narrow, resonance leads to a strong increase in amplitude, as a result of which the material is destroyed.

Example of a constant force

Another example where the destructive effect was manifested was the collapse of the Tacoma Suspension Bridge. This case and the video of the wave-like rocking of the structure are even recommended for viewing at university physics departments, as the most textbook example of such a resonance phenomenon.

The destruction of a suspension bridge by wind is an illustration of how a relatively constant force causes resonance . The following happens:

• a gust of wind deflects part of the structure - an external force contributes to the occurrence of vibrations;
• when the structure moves in reverse, air resistance is not enough to dampen the vibration or reduce its amplitude;
• due to the elasticity of the system, a new movement begins, which strengthens the wind, which continues to blow in one direction.

This is an example of the behavior of a complex object, where resonance develops against a background of high quality factor and significant elasticity, under the influence of constant force in one direction. Unfortunately, the Tacoma Bridge is not the only example of structural collapse. Cases have been and are being observed all over the world, including in Russia.

Resonance can also be used under controlled, well-defined conditions. Among the many examples, one can easily recall radio antennas, even those developed by amateurs. The principle of resonance when absorbing energy is applied here electromagnetic wave. Each system is developed for a separate frequency band in which it is most effective.

MRI installations use a different type of phenomenon - different absorption of vibrations by cells and structures of the human body. The nuclear magnetic resonance process uses radiation of different frequencies. The resonance that occurs in tissues leads to easy recognition of specific structures. By changing the frequency, you can explore certain areas and solve various problems.

March 02 2016

Resonance is a sharp increase in the amplitude of forced oscillations, which occurs when the frequency of the external influence approaches certain values ​​(resonance frequencies) determined by the properties of the oscillatory system. An increase in amplitude occurs when the external (exciting) frequency coincides with the internal (natural) frequency of the oscillatory system. With the help of resonant phenomena, even very weak harmonic vibrations can be isolated and/or amplified. Resonance is a phenomenon in which the oscillatory system is particularly responsive to the influence of a certain frequency of the driving force.

There are quite a few situations in our lives in which resonance manifests itself. For example, if you bring a ringing tuning fork to a stringed musical instrument, the acoustic wave emanating from the tuning fork will cause vibration of the string tuned to the frequency of the tuning fork, and it will sound itself.

Another example, the well-known experiment with a thin-walled glass. If you measure the frequency of sound at which a glass rings, and apply sound with the same frequency from a frequency generator, but with a larger amplitude, through an amplifier and speaker back to the glass, its walls resonate with the frequency of the sound coming from the speaker and begin to vibrate. Increasing the amplitude of this sound to a certain level leads to the destruction of the glass.

Our Orthodox ancestors, tens of thousands of years before the arrival of Christianity in Rus', knew well about the power of bell ringing and tried to install a bell tower in every village! Due to this, in the Middle Ages, Rus', rich in church bells, avoided the devastating plague epidemics, unlike Europe (Gaul), in which holy inquisitors burned at the stake not only all scientists and knowledgeable people, but also all the ancient “heretical” books written in the Glagolitic alphabet that kept unique knowledge of our ancestors, including the power of resonance!

Thus, all Orthodox knowledge accumulated over centuries was prohibited, destroyed and replaced by the new Christian faith. However, to this day, data on bioresonance are prohibited. Even after centuries, any information about treatment methods that do not bring profit to the pharmaceutical industry is kept silent. While the annual multi-billion dollar turnover of pharmaceuticals is growing every year.

A striking example of the use of resonant frequencies in Rus', and this is a fact that cannot be avoided. When a plague epidemic broke out in Moscow in 1771 (1771), Catherine II sent Count Orlov from St. Petersburg with four Life Guards and a huge staff of doctors. All life in Moscow was paralyzed. In order to ward off the “pestilence”, the laity fumigated their homes, lit huge fires in the streets, and all of Moscow was shrouded in black smoke, since it was then believed that the plague spread through the air, but this did not help much. They also rang the alarm (the largest bell) and all the smaller bells with all their might for 3 days in a row, as they firmly believed that the ringing of the bells would ward off terrible misfortune from the city. A few days later the epidemic began to recede. "What's the secret?" - you ask. In fact, the answer lies on the surface.

Now let’s look at a well-known example of the use of bioresonance in our time. In order to maintain the purity of the experiment, doctors placed metal plates in the ward with cancer patients, similar to those used in ancient monasteries, so that the patients could not associate the bells with the church, and self-hypnosis, born involuntarily, could not significantly affect the results of the research. When selecting individual frequencies for each patient, many titanium plates of various sizes were used. The result exceeded all expectations!

After exposure to acoustic waves of a certain frequency on the biologically active points of the patients, 30% of the patients stopped having pain and were able to fall asleep, and another 30% of the patients stopped having pain that was not relieved by the strongest narcotic anesthetics!

Currently, to achieve the resonance effect, there is no need to use huge bells, but there is a unique opportunity to use the achievements of science and technology, created electronic devices based on frequency resonance, in other words, Smart Life bioresonance therapy devices.

The resonance effect in biological structures can be caused by:

Acoustic waves

Mechanical impact

Electromagnetic waves in the visible and radio frequency ranges

Magnetic field pulses

Pulses of weak electric current

Pulsed thermal effects

That is, the resonance effect in biological structures can be caused by external influences and any physical phenomena that arise during biochemical reactions inside a living cell. Moreover, each biological structure has its own unique frequency spectrum that accompanies biochemical processes and responds to external influences, both the main resonant frequency and higher or lower harmonics from the main frequency, with an amplitude as many times greater as these harmonics are distant from the frequency of the main resonance .

How can you use the power of resonance in everyday life, and what method of influence should you choose?

Acoustic waves

Guess what happens to tartar when it is removed, using ultrasound in the dentist's office or when breaking up kidney stones? The answer is obvious. And without a doubt, acoustic exposure is an excellent opportunity for healing the body, if not for one “but”. Bells weigh a lot, are expensive, create a lot of noise, and can only be used permanently.

To cause at least any noticeable effect from the influence of a pulsating magnetic field on the entire body, it is necessary to make an electromagnet of enormous size and weighing a couple of tons; it will occupy half the room and consume a lot of electricity. The inertia of the system will not allow its use at high frequencies. Small electromagnets can only be used locally due to their short range. You also need to know exactly the areas on the body and the frequency of exposure. The conclusion is disappointing: using a magnetic field to treat diseases is not economically feasible at home.

Resonance is one of the most interesting physical phenomena. And the deeper our knowledge about the world around us becomes, the more clearly the role of this phenomenon can be seen in various areas of our lives - in music, medicine, radio engineering and even on the playground.

What is the meaning of this concept, the conditions for its emergence and manifestation?

Natural and forced vibrations. Resonance

Let's remember a simple and pleasant entertainment - swinging on a hanging swing.

By applying very little force at the right moment, a child can rock an adult. But for this, the frequency of the influence of the external force must coincide with the natural frequency of the swing. Only in this case will the amplitude of their oscillations increase noticeably.

So, resonance is the phenomenon of a sharp increase in the amplitude of vibrations of a body, when the frequency of its own vibrations coincides with the frequency of the action of an external force.

First of all, let's understand the concepts - natural and forced vibrations. Proper - inherent in all bodies - stars, strings, springs, nuclei, gases, liquids... They usually depend on the coefficient of elasticity, mass of the body and its other parameters. Such oscillations arise under the influence of a primary push carried out by an external force. So, in order to vibrate a load suspended on a spring, it is enough to pull it a certain distance. The resulting natural oscillations will be damped, since the oscillation energy is spent on overcoming the resistance of the oscillatory system itself and the environment.

Forced vibrations occur when a body is exposed to a third-party (external) force with a certain frequency. This external force is also called coercive force. It is very important that this external force acts on the body at the right moment and in the right place. It is she who replenishes energy losses and increases it during the body’s own vibrations.

Mechanical resonance

A very striking example of the manifestation of resonance is several cases of bridge collapses when a company of soldiers walked across them in formation.

The chiseled step of the soldiers' boots coincided with the natural frequency of vibration of the bridge. It began to vibrate with such an amplitude for which its strength was not designed and... fell apart. Then a new military team was born "…out of step". It sounds when a company of soldiers on foot or on horseback crosses the bridge.

If you have ever traveled by train, then the most attentive of you have noticed the noticeable swaying of the carriages when its wheels hit the rail joints. This is how the car responds, that is, it resonates with the vibrations that arise when overcoming these gaps.

Ship instruments are equipped with massive stands or suspended on soft springs to avoid resonance of these ship parts with vibrations of the ship hull. When the ship's engines are started, the ship can resonate with their operation so much that this threatens its strength.

The examples given are sufficient to demonstrate the need to take resonance into account. But we sometimes use mechanical resonance without noticing it. When pushing out a car stuck in the road mud, the driver and his volunteer assistants first rock it and then unanimously push it forward in the direction of travel.

When swinging a heavy bell, bell ringers also unconsciously use this phenomenon.

They rhythmically, in time with the bell's own vibrations, pull the cord attached to it, increasing the amplitude of the vibrations.

There are instruments that measure the frequency of electric current. Their action is based on the use of resonance.

Acoustic resonance

On the pages of our website we... Let's continue our conversation, supplementing it with examples of the manifestation of acoustic or sound resonance.

Why do musical instruments, especially the guitar and violin, have such beautiful bodies? Is it really just to look beautiful? It turns out not. It is needed for the correct sound of the entire sound palette produced by the instrument. The sound produced by the guitar string itself is quite quiet. To strengthen it, the strings are placed on top of a body that has a certain shape and size. The sound entering the guitar resonates with different parts of the body and intensifies.

The strength and purity of sound depends on the quality of the wood, and even on the varnish with which the instrument is coated.

Available resonators in our vocal apparatus. Their role is played by a variety of air cavities surrounding the vocal cords. They amplify the sound, shape its timbre, enhancing precisely those vibrations whose frequency is close to their own. The ability to use the resonators of one’s vocal apparatus is one of the aspects of a singer’s talent. F.I. mastered it perfectly. Chaliapin.

They say that when this great artist sang at the top of his lungs, candles went out, chandeliers shook and cut glasses cracked.

Those. The phenomenon of sound resonance plays a huge role in the delightful world of sounds.

Electrical resonance

Electric circuits did not escape this phenomenon either. If the frequency of change in external voltage will coincide with the frequency of natural oscillations of the circuit, then electrical resonance may occur. As always, it manifests itself in a sharp increase in both current and voltage in the circuit. This is fraught with a short circuit and failure of devices included in the circuit.

However, it is resonance that allows us to tune in to the frequency of a specific radio station. Typically, the antenna receives many frequencies from different radio stations. By rotating the tuning knob, we change the frequency of the receiving circuit of the radio receiver.

When one of the frequencies arriving at the antenna coincides with this frequency, then we will hear this radio station.

Schumann waves

Between the Earth's surface and its ionosphere there is a layer in which electromagnetic waves propagate very well. This celestial corridor is called a waveguide. The waves generated here can circle the Earth several times. But where do they come from? It turned out that they occur during lightning strikes.

Professor Schumann of the Technical University of Munich calculated their frequency. It turned out that it is equal to 10 Hz. But it is precisely with this rhythm that the human brain oscillates! This amazing fact could not be a mere coincidence. We live inside a giant waveguide, which controls our body with its rhythm. Further research confirmed this assumption. It turned out that distortion of Schumann waves, for example, during magnetic storms, worsens people's health.

Those. For normal human well-being, the rhythm of the most important vibrations of the human body must resonate with the frequency of Schumann waves.

Electromagnetic smog from the operation of household and industrial electrical appliances distorts the natural waves of the Earth, and destroys our subtle relationships with our planet.

All objects in the Universe are subject to the laws of resonance. Even human relationships are subject to these laws. So, when choosing friends for ourselves, we look for people like ourselves, with whom we are interested, with whom we are “on the same wavelength.”

If this message was useful to you, I would be glad to see you

Forced vibrations- vibrations that occur under the influence of external forces that change over time.

Self-oscillations differ from forced oscillations in that the latter are caused by periodic external influence and occur with the frequency of this influence, while the occurrence of self-oscillations and their frequency are determined by the internal properties of the self-oscillatory system itself.

Newton's second law for such an oscillator will be written in the form: . If you enter the notation: and replace the acceleration with the second derivative of the coordinate with respect to time, we obtain the following differential equation:

The solution to this equation will be the sum of the general solution of the homogeneous equation and the particular solution of the inhomogeneous one. The general solution of the homogeneous equation has already been obtained here and it has the form:

Where A,φ are arbitrary constants that are determined from the initial conditions.

Let's find a particular solution. To do this, we substitute a solution of the form: into the equation and obtain the value for the constant:

Then the final solution will be written as:

Reasonì ns(fr. resonance, from lat. resono- I respond) is the phenomenon of a sharp increase in the amplitude of forced oscillations, which occurs when the frequency of external influence approaches certain values ​​(resonant frequencies) determined by the properties of the system.

An increase in amplitude is only a consequence of resonance, and the reason is the coincidence of the external (exciting) frequency with the internal (natural) frequency of the oscillatory system. Using the phenomenon of resonance, even very weak periodic oscillations can be isolated and/or amplified. Resonance is the phenomenon that at a certain frequency of the driving force the oscillatory system is especially responsive to the action of this force.

The most familiar mechanical resonance system to most people is a regular swing. If you push the swing according to its resonant frequency, the range of motion will increase, otherwise the motion will fade. The resonant frequency of such a pendulum can be found with sufficient accuracy in the range of small displacements from the equilibrium state using the formula:

Where g is the acceleration due to gravity (9.8 m/s² for the Earth’s surface), and L- length from the point of suspension of the pendulum to its center of mass

Resonance phenomena can cause irreversible damage in various mechanical systems, such as improperly designed bridges. Thus, in 1905, the Egyptian Bridge in St. Petersburg collapsed while a horse squadron was passing across it, and in 1940, the Tacoma Bridge in the USA collapsed. To prevent such damage, there is a rule that forces the formation of soldiers to break stride when passing bridges.

R
resonant curve of an oscillating circuit Resonance curve of the oscillatory circuit: w0 - frequency of natural oscillations; W is the frequency of forced oscillations; DW is a frequency band near w0, at the boundaries of which the oscillation amplitude is V = 0.7 Vmakc. The dotted line is the resonance curve of two connected circuits.

26. Basic concepts and starting points of thermodynamics. Reversible and irreversible processes. Circular processes (cycles).

Thermodynamics- a branch of physics that studies the relationships and transformations of heat and other forms of energy

List of principles of thermodynamics

The first law of thermodynamics is the law of conservation of energy as applied to thermodynamic systems. (The amount of heat received by the system goes to change its internal energy and do work against external forces)

Δ U = Q − A

The second law of thermodynamics imposes restrictions on the direction of thermodynamic processes, prohibiting the spontaneous transfer of heat from less heated bodies to more heated ones. Also formulated as the law of increasing entropy. dS≥0 ( Clausius inequality)

The third law of thermodynamics tells how entropy behaves near absolute zero temperatures.

Reversible process(that is, equilibrium) is a thermodynamic process that can occur in both the forward and reverse directions, passing through the same intermediate states, and the system returns to its original state without energy expenditure, and no macroscopic changes remain in the environment.

A reversible process can be made to flow in the opposite direction at any time by changing any independent variable by an infinitesimal amount.

Reversible processes produce the most work. It is generally impossible to obtain more work from the system. This gives reversible processes theoretical importance. In practice, a reversible process cannot be realized. It flows infinitely slowly, and you can only get closer to it.

Irreversible is a process that cannot be carried out in the opposite direction through all the same intermediate states. All real processes are irreversible. Examples of irreversible processes: diffusion, thermal conductivity, etc.

Thermodynesì logical qiì kly- circular processes in thermodynamics, that is, processes in which the initial and final parameters that determine the state of the working fluid (pressure, volume, temperature, entropy) coincide.

Thermodynamic cycles are models of processes occurring in real heat engines to convert heat into mechanical work. The only reversible cycle for a machine in which heat transfer occurs only between the working fluid, the heater and the refrigerator is the Carnot Cycle. There are also other cycles (for example, Stirling and Ericsson cycles), in which reversibility is achieved by introducing an additional heat reservoir - a regenerator