What is called mechanical movement: definition and formula. What does mechanics study

“Think of the benefit that good examples bring us, and you will find that the memory of great people is no less useful than their presence”

Mechanics is one of the most ancient Sciences. It arose and developed under the influence public practice requests and also thanks to abstracting activity of human thinking. Even in prehistoric times, people created buildings and observed the movement of various bodies. Many laws of mechanical motion and balance of material bodies were known by mankind through repeated repetitions, purely experimentally. This socio-historical experience, passed down from generation to generation, and was the the source material on the analysis of which mechanics as a science developed. The emergence and development of mechanics was closely associated with production, with needs human society. “At a certain stage in the development of agriculture,” writes Engels, “and in certain countries (raising water for irrigation in Egypt), and especially along with the emergence of cities, large buildings and the development of crafts, developed and Mechanics. Soon it also becomes necessary for shipping and military affairs.

First the manuscripts and scientific reports in the field of mechanics that have survived to this day belong to ancient scholars of Egypt and Greece. The oldest papyri and books, in which studies of some of the simplest problems of mechanics have been preserved, relate mainly to various problems. statics, i.e. the doctrine of balance. First of all, here it is necessary to name the works of the outstanding philosopher of ancient Greece (384-322 BC), who introduced the name Mechanics for a wide field of human knowledge, in which the simplest movements of material bodies, observed in nature and created by man during his activities, are studied.

Aristotle was born in the Greek colony of Stagira in Thrace. His father was a physician to the Macedonian king. In 367, Aristotle settled in Athens, where he received a philosophical education at the Academy of the famous idealist philosopher in Greece. Plato. In 343 Aristotle took over teacher of Alexander the Great(Alexander the Great said: “I honor Aristotle on a par with my father, since if I owe my life to my father, then I owe Aristotle everything that gives her a price”), later the famous commander of the ancient world. His philosophical school, called the school peripatetics, Aristotle founded in 335 in Athens. Some philosophical provisions of Aristotle have not lost their significance to the present day. F. Engels wrote; "The ancient Greek philosophers were all born elemental dialecticians, and Aristotle, the most universal head among them, has already explored all the essential forms of dialectical thinking." But in the field of mechanics, these broad universal laws of human thinking did not receive a fruitful reflection in the works of Aristotle.

Archimedes owns a large number technical inventions, including the simplest water-lifting machine (archimedean screw), which has found application in Egypt for draining cultivated lands flooded with water. He showed himself as military engineer while defending his hometown of Syracuse (Sicily). Archimedes understood the power and great significance for mankind of accurate and systematic scientific research, and proud words are attributed to him: “ Give me a place to stand on and I will move the earth."

Archimedes was killed by the sword of a Roman soldier during the massacre arranged by the Romans during the capture of Syracuse. Tradition says that Archimedes, immersed in the consideration of geometric figures, said to a soldier who approached him: "Do not touch my drawings." The soldier, seeing in these words an insult to the power of the victors, cut off his head, and the blood of Archimedes stained his scientific work.

famous ancient astronomer Ptolemy(II century AD - there is evidence that Ptolemy (Claudius Ptolemaeus) lived and worked in Alexandria from 127 to 141 or 151. According to Arabic legend, he died at the age of 78.) in his work " The Great Mathematical Construction of Astronomy in 13 Books"developed a geocentric system of the world, in which the apparent movements of the firmament and planets were explained on the assumption that the Earth is motionless and is at the center of the universe. The entire firmament makes a complete revolution around the Earth in 24 hours, and the stars participate only in the daily movement, while maintaining their relative position unchanged; planets, moreover, move relative to the celestial sphere, changing their position relative to the stars. The laws of the apparent motions of the planets were established by Ptolemy to such an extent that it became possible to predict their positions relative to the sphere of the fixed stars.

However, the theory of the structure of the universe, created by Ptolemy, was erroneous; it led to extraordinarily complex and artificial schemes of the motion of the planets and in a number of cases could not fully explain their apparent movements relative to the stars. Particularly large inconsistencies between calculations and observations were obtained with predictions of solar and lunar eclipses made many years ahead.

Ptolemy did not adhere strictly to the methodology of Aristotle and conducted systematic experiments on the refraction of light. Physiological-optical observations Ptolemy have not lost their interest to date. The angles of light refraction found by him during the transition from air to water, from air to glass and from water to glass were very accurate for its time. Ptolemy remarkably combined strict mathematician and subtle experimenter.

In the era of the Middle Ages, the development of all sciences, as well as mechanics, was strongly slowed down. Moreover, during these years the most valuable monuments of science, technology and art of the ancients were destroyed and destroyed. Religious fanatics wiped out all the achievements of science and culture from the face of the earth. Most of the scientists of this period blindly adhered to the scholastic method of Aristotle in the field of mechanics, considering all the provisions contained in the writings of this scientist to be unconditionally correct. The geocentric system of the world of Ptolemy was canonized. Speech against this system of the world and the basic principles of the philosophy of Aristotle were considered a violation of the foundations of the Holy Scripture, and researchers who decided to do this were declared heretics. “The priesthood killed the living in Aristotle and immortalized the dead,” wrote Lenin. Dead, empty scholasticism filled the pages of many treatises. Ridiculous problems were posed, and exact knowledge was persecuted and withered. A large number of works on mechanics in the Middle Ages were devoted to finding " perpetuum mobile”, i.e. perpetual motion machine operating without receiving energy from outside. Most of these works contributed little to the development of mechanics (The ideology of the Middle Ages was well expressed by Mahomet, saying: "If the sciences teach what is written in the Koran, they are superfluous; if they teach otherwise, they are godless and criminal"). “The Christian Middle Ages left nothing to science,” says F. Engels in Dialectics of Nature.

The intensive development of mechanics began in renaissance from the beginning of the 15th century in Italy, and then in other countries. In this era, especially great progress in the development of mechanics was achieved thanks to the work (1452-1519), (1473-1543) and Galilee (1564-1642).

Famous Italian painter, mathematician, mechanic and engineer, Leonardo da Vinci engaged in research on the theory of mechanisms (he built an elliptical lathe), studied friction in machines, investigated the movement of water in pipes and the movement of bodies along an inclined plane. He was the first to recognize the extreme importance of the new concept of mechanics - the moment of force relative to a point. Investigating the balance of forces acting on the block, he established that the role of the shoulder of force is played by the length of the perpendicular dropped from the fixed point of the block to the direction of the rope carrying the load. The equilibrium of the block is possible only if the products of forces and the lengths of the corresponding perpendiculars are equal; in other words, the equilibrium of the block is possible only under the condition that the sum of the static moments of forces relative to the weight gain point of the block will be equal to zero.

A revolutionary revolution in the views on the structure of the universe was carried out by a Polish scientist who, as figuratively written on his monument in Warsaw, "stopped the Sun and moved the Earth." new, heliocentric system of the world explained the movement of the planets, based on the fact that the Sun is a fixed center, around which all the planets move in circles. Here are the original words of Copernicus, taken from his immortal work: “What appears to us as the movement of the Sun does not come from its movement, but from the movement of the Earth and its sphere, with which we revolve around the Sun, like any other planet. So, the Earth has more than one movement. The apparent simple and retrograde motions of the planets are not due to their motion, but to the motion of the Earth. Thus, one movement of the Earth is sufficient to explain so many apparent inequalities in the sky.

In the work of Copernicus, the main feature of the motion of the planets was revealed and calculations were made related to the predictions of solar and lunar eclipses. The explanations of the apparent return motions of Mercury, Venus, Mars, Jupiter, and Saturn relative to the sphere of the fixed stars have acquired clarity, distinctness, and simplicity. Copernicus clearly understood the kinematics of the relative motion of bodies in space. He writes: “Every perceived change in position occurs due to the movement of either the observed object or the observer, or due to the movement of both, if, of course, they are different from each other; for when the observed object and the observer move in the same way and in the same direction, no movement is noticed between the observed object and the observer.

Truly scientific Copernican theory made it possible to obtain a number of important practical results: to increase the accuracy of astronomical tables, to reform the calendar (introducing a new style), and to determine the length of the year more strictly.

Works of the brilliant Italian scientist Galilee were fundamental to the development speakers.
Dynamics as a science was founded by Galileo, who discovered many very important properties of uniformly accelerated and uniformly slow motions. The foundations of this new science were set forth by Galileo in a book entitled "Conversations and Mathematical Proofs Concerning Two New Branches of Science Relating to Mechanics and Local Motion." In chapter III, on dynamics, Galileo writes: “We are creating a new science, the subject of which is extremely old. In nature, there is nothing ancient movement, but it is precisely with regard to it that philosophers have written very little significant. Therefore, I have repeatedly studied its features by experience, which are quite deserving of this, but until now either unknown or unproven. So, for example, they say that the natural motion of a falling body is accelerated motion. However, the extent to which the acceleration increases has not yet been indicated; as far as I know, no one has yet proved that the spaces traversed by a falling body at the same time intervals are related to each other as successive odd numbers. It was also noticed that the thrown bodies or projectiles describe a certain curved line, but no one indicated that this line is a parabola.

Galileo Galilei (1564-1642)

Before Galileo, forces acting on bodies were usually considered in a state of equilibrium and the action of forces was measured only by static methods (lever, scales). Galileo pointed out that force is the cause of the change in speed, and thus established dynamic method comparison of forces. Galileo's research in the field of mechanics is important not only for the results that he managed to obtain, but also for his consistent introduction to mechanics. experimental movement research method.

So, for example, the law of isochronism of pendulum oscillations at small angles of deflection, the law of motion of a point along an inclined plane were investigated by Galileo through carefully staged experiments.

Thanks to the works of Galileo, the development of mechanics is firmly associated with the demands technology, and scientific experiment systematically introduced as fruitful research method phenomena of mechanical movement. Galileo in his conversations directly says that observing the work of the “first” masters in the Venetian arsenal and talking with them helped him understand “the causes of phenomena that were not only amazing, but also seemed at first completely unbelievable.” Many provisions of Aristotle's mechanics were refined by Galileo (as, for example, the law of the addition of motions) or very ingeniously refuted by purely logical reasoning (refutation by setting up experiments was considered insufficient at that time). We present here Galileo's proof to characterize the style. refuting Aristotle's position that heavy bodies on the surface of the Earth fall faster, and light bodies fall more slowly. The reasoning is given in the form of a conversation between a follower of Galileo (Salviati) and Aristotle (Simplicio):

« Salviati: ... Without further experiments, by a brief but convincing reasoning, we can clearly show the incorrectness of the statement that heavier bodies move faster than lighter ones, implying bodies of the same substance, i.e. such as those of which Aristotle speaks . In fact, tell me, Señor Simplicio, do you admit that every falling body has a certain speed by nature, which can be increased or decreased only by introducing a new force or obstacle?
Simplicio: I have no doubt that the same body in the same medium has a constant speed determined by nature, which cannot increase except by the application of a new force, or decrease except by an obstacle that slows down the movement.
Salviati: Thus, if we have two falling bodies, the natural speeds of which are different, and we combine the faster one with the slower one, then it is clear that the motion of the body falling faster will be somewhat delayed, and the motion of the other will be somewhat accelerated. Do you object to this position?
Simplicio: I think that this is quite correct.
Salviati: But if this is so, and if at the same time it is true that a large stone moves, say, with a speed of eight cubits, while another, smaller one, with a speed of four cubits, then by joining them together, we should get a speed less than eight elbows; but two stones joined together make a body greater than the original, which had a speed of eight cubits; therefore, it turns out that a heavier body moves at a lower speed than a lighter one, and this is contrary to your assumption. You see now how, from the position that heavier bodies move faster than lighter ones, I could conclude that heavier bodies move less quickly.

The phenomena of a uniformly accelerated fall of a body on Earth were observed by numerous scientists before Galileo, but none of them could discover the true causes and correct laws that explain these everyday phenomena. Lagrange notes on this occasion that "an extraordinary genius was needed to discover the laws of nature in such phenomena that were always before our eyes, but the explanation of which, nevertheless, always eluded the research of philosophers."

So, Galileo was the founder of modern dynamics. Galileo clearly understood the laws of inertia and independent action of forces in their modern form.

Galileo was an outstanding observing astronomer and an ardent supporter of the heliocentric worldview. Radically improving the telescope, Galileo discovered the phases of Venus, the satellites of Jupiter, spots on the Sun. He waged a persistent, consistently materialistic struggle against the scholasticism of Aristotle, the dilapidated system of Ptolemy, and the anti-scientific canons of the Catholic Church. Galileo is one of the great men of science, "who knew how to break the old and create the new, in spite of any obstacles, in spite of everything."
The works of Galileo were continued and developed (1629-1695), who developed the theory of oscillations of a physical pendulum and installed laws of action of centrifugal forces. Huygens extended the theory of accelerated and retarded motions of one point (translational motion of a body) to the case of a mechanical system of points. This was a significant step forward, as it made it possible to study the rotational motions of a rigid body. Huygens introduced the concept of moment of inertia of the body about the axis and defined the so-called swing center" physical pendulum. When determining the swing center of a physical pendulum, Huygens proceeded from the principle that "a system of weighty bodies moving under the influence of gravity cannot move in such a way that the common center of gravity of the bodies rises above its original position." Huygens also showed himself as an inventor. He created the design of pendulum clocks, invented the balancer-regulator of the pocket watch, built the best astronomical tubes of that time and was the first to clearly see the ring of the planet Saturn.

Mechanics is one of the sections physics. Under mechanics usually understand classical mechanics. Mechanics is a science that studies the movement of bodies and the interactions between them that occur in this case.

In particular, each body at any moment of time occupies a certain position in space relative to other bodies. If, over time, the body changes position in space, then they say that the body moves, performs a mechanical movement.

Mechanical movement is called a change in the relative position of bodies in space over time.

The main task of mechanics- determining the position of the body at any time. To do this, you need to be able to briefly and accurately indicate how the body moves, how its position changes over time during this or that movement. In other words, to find a mathematical description of the movement, that is, to establish links between the quantities characterizing the mechanical movement.

When studying the movement of material bodies, concepts such as:

• material point- a body whose dimensions under given conditions of motion can be neglected. This concept is used in translational motion, or when, in the motion under study, the rotation of the body around its center of mass can be neglected,
• absolutely rigid body- a body, the distance between any two points of which does not change. The concept is used when the deformation of the body can be neglected.
• continuum changeable environment- the concept is applicable when the molecular structure of the body can be neglected. Used in the study of the movement of liquids, gases, deformable solids.

classical mechanics based on Galileo's principle of relativity and Newton's laws. Therefore, it is also called Newtonian mechanics .

Mechanics studies the movement of material bodies, the interactions between material bodies, the general laws of changes in the positions of bodies over time, as well as the causes that cause these changes.

The general laws of mechanics imply that they are valid when studying the motion and interaction of any material bodies (except elementary particles) from microscopic sizes to astronomical objects.

Mechanics includes the following sections:

• kinematics(studies the geometric property of the movement of bodies without the reasons that caused this movement),
• dynamics(studies the movement of bodies, taking into account the causes that caused this movement),
• statics(studies the balance of bodies under the action of forces).

It should be noted that these are not all the sections that are included in the mechanics, but these are the main sections that the school curriculum studies. In addition to the sections mentioned above, there are a number of sections, both of independent importance and closely related to each other and to the indicated sections.

For example:

• continuum mechanics (includes hydrodynamics, aerodynamics, gas dynamics, elasticity theory, plasticity theory);
• quantum mechanics;
• mechanics of machines and mechanisms;
• oscillation theory;
• mechanics of variable masses;
• impact theory;
• and etc.

The appearance of additional sections is associated both with going beyond the limits of applicability of classical mechanics (quantum mechanics), and with a detailed study of the phenomena occurring during the interaction of bodies (for example, the theory of elasticity, the theory of impact).

But, despite this, classical mechanics does not lose its significance. It is sufficient to describe a wide range of observed phenomena without the need to resort to special theories. On the other hand, it is easy to understand and provides a basis for other theories.

AUTO OSCILLATIONS- undamped oscillations of a physical system, which are supported by an energy source located in the system itself. Amplitude and period A.K. determined by the properties of the system.

ACOUSTICS- 1) The field of physics that studies the processes of origin, propagation and registration of sound waves. 2) Sound characteristics of the premises.

AMPLITUDE OF OSCILLATIONS- highest value xm , which reaches the physical quantity X(displacement, current strength, electric field strength, etc.), performing harmonic oscillations, i.e., changing according to the law x= xm cos(ω . t+ φ ) , where t - time, xm, ω , φ - constant (with harmonic vibrations) values. In other words, A. determines the "range" of fluctuations. In this sense, the term A. can be applied to non-harmonic vibrations.

AMPLITUDE MODULATION- the process of changing the amplitude of oscillations with a frequency much lower than the frequency of the oscillations themselves. Used in radio engineering.

HYDROMETER- a device for measuring the density of a liquid. Action A. based on the law of Archimedes. Density is determined by the depth of immersion A. The most common are A. constant weight, in which the scales are usually graduated in units of density. In everyday life, they are used to determine the fat content of milk (lactometers, lactodensimeters), alcohol content (alcohol meters), sugar (sugar meters), electrolyte concentration in car batteries. In these cases, the scales may be graduated in % by volume or mass.

ARCHIMEDE'S LAW- the law of hydro- and aerostatics: a body immersed in a liquid or gas is subjected to a buoyant force directed against the action of gravity, numerically equal to the weight of the liquid or gas displaced by the body, and applied at the center of gravity of the immersed part of the body. Other gr. scientist Archimedes in 212. BC. It is the basis of the theory of swimming bodies.

TRAVELING WAVES- waves that carry energy along the direction of their propagation. (cf.).

is one of the basic equations of hydrodynamics, expressing the law of conservation of energy for a steady flow of an ideal fluid, i.e. flow at which its parameters (velocity, pressure) do not depend on time: the sum of pressure and densities of kinetic and potential energies in a stationary flow of an ideal fluid remains constant for any flow section:

BLOCK- the simplest device in the form of a wheel with a groove around the circumference through which a thread, rope, rope or chain is stretched. It is used to change the direction of the force (fixed) or to obtain a gain in strength (mobile). Genus lever.

THE WEIGHT- the force with which the body, due to gravity, acts on the support or suspension. V. - force, paired according to the 3rd Newton's z-well, the force of elasticity (support reaction or suspension tension).

WAVE SURFACE- a set of points in the medium in which at a given time the phase of the wave has the same value.

WAVES are disturbances (changes in the state of a medium or field) propagating in space at a finite speed. The propagation of waves is associated with the transfer of energy without the transfer of matter, while phenomena are possible reflections, refractions, interferences. diffraction, polarization, absorption and scattering of waves. (See, electromagnetic waves).

ENGINE- a machine that converts various types of energy into mechanical work.

MOVEMENT MECHANICAL- the process of changing the position of a body in space relative to other bodies over time.

MOTION BY INERTIA- mechanical movement occurring with compensation or without external influences. In everyday life, unlike scientific ideas, under D.I. understand D. under the influence of forces of resistance.

DEFORMATION- a change in the shape or size of a body (or body part) due to the mechanical action of external bodies, during heating or cooling, changes in humidity, and other interactions that cause a change in the relative arrangement of body particles. see also .

DEFORMATION PLASTIC- type of D., a sign of which is the preservation of changes in the shape and size of the deformed body after the cessation of external influence.

ELASTIC DEFORMATION- a type of D., a sign of which is the restoration of the shape and size of a deformed body after the cessation of external influence.

DAMPING OF OSCILLATIONS- gradual weakening natural vibrations due to energy losses of the oscillatory system. Z.k. leads to a decrease in the amplitude of oscillations.

SOUND(sound waves) - elastic waves propagating in solid, liquid and gaseous media. Depending on the frequency of vibrations, sounding is conditionally subdivided into (frequency up to 16 Hz), audible sound ( 16 Hz - 20 kHz), ultrasound ( 20 kHz - 1 GHz) and hypersound (more than 1 GHz).

SOUND PRESSURE- variable pressure, excess over equilibrium, arising from the passage of a sound wave in a liquid or gaseous medium.

RADIATION- 1) I. waves and particles - the process of emitting sound waves by sound sources, radio waves - by antennas, light and X-rays - by atoms and molecules, α -, β -particles and γ -rays by atomic nuclei. 2) These waves and particles themselves are like moving objects. (Cm. Alpha rays, Beta rays etc.)

IMPULSE FORCE- a vector physical quantity used to describe the action of a force on a body over a certain period of time and equal to the product of the force vector by this period of time. Unit I.s. in SI, newton second. At a constant force I.s. is equal to the change in the momentum of the body on which the given force acted during a given period of time.

BODY PULSE, the amount of motion is a vector physical quantity equal to the product of the mass of the body and its speed. I. of a mechanical system is equal to the vector sum of I. of all parts of the system. For a closed system, . The unit of I. in SI is kilogram-meter per second.

PULSE CONSERVATION LAW- the law of mechanics: pulse of any closed system for all processes occurring in the system remains constant (conserved) and can only be redistributed between parts of the system as a result of their interaction.

inertness- the property of various material objects to acquire different accelerations under the same external influences from other bodies. Inherent in different bodies to varying degrees. The quantity that makes it possible to describe the property of the I. of a body in translational motion is its weight, and in rotational motion moment of inertia. Wed .

INERTIAL REFERENCE SYSTEM- a frame of reference in which the body maintains a state of rest or uniform rectilinear motion in the absence of interaction with other bodies or compensation for external influences (see). A frame of reference that is at rest or moves in a straight line and uniformly with respect to some I.S.O. is itself inertial. In I.s.o. performed Galilean principle of relativity and Einstein's principle of relativity.

INERTIA LAW- Newton's first law (see).

INERTIA- the phenomenon of preservation of the speed of rectilinear uniform motion or state of rest in the absence or compensation of external influences. Wed .

WAVE INTENSITY, radiation flux density - a physical quantity equal to the ratio of the wave power to the area of ​​the wave front for a uniform distribution of radiation energy. The SI unit is .

SOUND INTENSITY, sound power is a physical quantity equal to the ratio of the energy carried by a sound wave through a surface located perpendicular to the direction of wave propagation to the surface area and the time interval during which the process took place. I.z. unit in SI - .

WAVE INTERFERENCE- the phenomenon of superposition of two or more waves, in which the energy of the resulting wave is redistributed in space. If the waves coherent, then in space a time-stable distribution of amplitudes with alternating maxima and minima (interference pattern) is obtained. Takes place for all waves, regardless of their nature. Wed wave diffraction.

INFRASOUND- elastic waves with a frequency of less than 16 Hz, which are not perceived by the human ear. Sources of I.: gas discharges in the atmosphere, wind, vibrations of the earth's crust and sea surface. Cm. sound, ultrasound, hypersound.

KEPLER'S LAWS- the laws of motion of the planets of the solar system. 1st law: Each planet moves in an elliptical orbit with the Sun at one of its foci. 2nd law: the radius vector drawn from the Sun to the planet "sweeps" equal areas in equal time intervals. 3rd law: the squares of the periods of revolution of the planets around the Sun are related as the cubes of the semi-major axes of their elliptical orbits.

KINEMATICS- a branch of mechanics that studies the ways of describing movements and the relationship between the quantities that describe these movements without taking into account their mass and the forces acting on them. Wed dynamic, static.

KINETIC ENERGY- a type of mechanical energy, the energy of a moving body. A scalar quantity equal to half the product of a body's mass times the square of its forward speed. Shows how much work must be done to accelerate a body of a given mass from rest to a given speed. K.e. of a mechanical system is equal to the sum of the kinetic energies of all parts of the system. The SI unit is the joule. Wed potential energy.

CLASSICAL MECHANICS- a physical theory that establishes the laws of motion of macroscopic bodies with velocities that are much lower compared to the speed of light. At the heart of K.m. lie.

COHERENCE- coordinated flow in time of several oscillatory or wave processes. Coherent called. oscillations with the same frequency (wavelength) and constant phase difference. K. is a necessary condition for the occurrence of interference (see. wave interference, light interference).

VASCULATION- movements (changes in state) characterized by a certain degree of repetition in time. There are K.: mechanical (K. pendulums, strings, plates, closed volumes of air, etc.), electromagnetic (K. electric current and voltage in oscillatory circuit or waveguide, alternating current, etc.) and electromechanical (K. piezoelectric and magnetostrictive emitters, etc.). The simplest periodic oscillations - .

oscillatory system- a system of bodies capable of free oscillations. Signs of K.s. - the presence of a position of stable equilibrium, low friction (electrical resistance).

AMOUNT OF MOVEMENT- the same as pulse.

CONSERVATIVE FORCES- forces, the work of which does not depend on the shape of the trajectory, but is determined only by the positions of the starting and ending points.

CIRCULAR FREQUENCY- the same as angular frequency

LAMINAR FLOW- an ordered flow of a viscous liquid or gas, characterized by the absence of mixing between adjacent layers of liquid or gas. Wed turbulent flow.

LORENTZ TRANSFORMATION- the relationship between the coordinates and moments of time of an event considered in two moving one relative to the other with any possible speeds. important in relativity theory. At speeds much lower than the speed of light in vacuum, they transform into Galileo transformation.

MICHELSON EXPERIENCE- an experiment designed to measure the effect of the Earth's movement on the value speed of light. Negative result M.o. became one of the experimental bases relativity theory.

Scalar quantity used to quantify properties inertia and phenomena of gravitation of material objects. According to special theory of relativity is proportional to the total energy of the body: , where with 2 is the square of the speed of light in vacuum. Unit in SI - kilogram(kg).

REST MASS- mass of an elementary particle (body) in the frame of reference in which this particle (body) is at rest (eg, in its own FR).

MATERIAL POINT- a mental model of a body of infinitely small size, but having mass. A real body can be considered as an M.T. if its dimensions are small compared to other characteristic dimensions that are essential for a given problem. For example, when considering the movement of a satellite around the Earth, the satellite can be taken as a material point, because its own dimensions are not negligible compared to the distance to the Earth or the length of the orbit.

PENDULUM- a rigid body (or system of bodies) capable of oscillating around a fixed point or axis. Cm. mathematical pendulum, physical pendulum.

PENDULUM MATHEMATICAL- idealized object : oscillatory system, consisting of material point and, suspended from a fixed point on a weightless inextensible thread (or rod) and the center of gravity (eg, the Earth). Mm. commits fluctuations in the vertical plane. For small fluctuations period fluctuations M.m. does not depend on amplitude and is expressed by the formula , where ℓ is the length of the thread, and g - . Wed spring pendulum.

SPRING PENDULUM- idealized object: oscillatory system, consisting of material point and attached to the end of a weightless spring. For small fluctuations period fluctuations M.p. does not depend on amplitude and is expressed by the formula , where m is the mass of a material point, k – rigidity springs. Wed mathematical pendulum.

MECHANICS- the science of the mutual movements of bodies in space and the interactions between them that occur in this case. Divided by kinematics, dynamics and statics. The main task is to determine the position of a body in space relative to other bodies at any time. Cm. classical mechanics, relativistic mechanics.

MECHANICAL ENERGY- the energy of mechanical motion and interaction of the bodies of the system or their parts. Equal to sum kinetic and potential energy this system. Wed internal energy.

MECHANICAL PRINCIPLE OF RELATIVITY- the same as Galileo's principle of relativity.

MICROPHONE- a device for converting sound vibrations into electrical ones.

- a constant physical quantity for a given material, which is a coefficient of proportionality between mechanical stress and relative elongation in: . M.Yu. E is equal to the mechanical stress that occurs in a deformed body when its length is doubled. The SI unit of measurement is pascal.

(moment of momentum) is a physical quantity equal to the vector product of the momentum of a material point and the radius vector: . In the simplest case of a material point rotating in a circular orbit, is equal to L=m× r. For a closed system of bodies remains constant (conserved).

MOMENT OF POWER relative to some axis - a physical quantity that describes the rotational effect of force when it acts on a solid body and is equal to the product of the modulus of force by shoulder of strength(the force is located in a plane perpendicular to the axis of rotation). If the rotation is counterclockwise, the moment of force is assigned the sign "+", if clockwise - "-". The SI unit is the newton meter ( N. m).

POWER- a scalar value equal to the ratio of work to the period of time for which it is completed. The SI unit is watt (W).

is a physical quantity equal to the ratio of the elastic force modulus to the cross-sectional area of ​​the deformable body . The SI unit is the pascal.

WEIGHTLESSNESS- the state of a mechanical system, in which the external gravitational field acting on the system does not cause mutual pressure of one part of the system on another and their deformation. Occurs during free fall of bodies, in artificial satellites and spacecraft moving with the engines turned off, i.e. when only gravitational forces act on the body.

NONINERTIAL REFERENCE SYSTEM- any frame of reference moving with acceleration relative to some inertial frame of reference. Cm. reference system.

NEWTON'S LAWS the three laws underlying Newtonian classical mechanics. 1st law (law of inertia): there are such frames of reference, relative to which the body moves in a straight line and uniformly or is at rest, if other bodies do not act on it or their actions are compensated. 2nd law (basic law of dynamics): the acceleration received by the body as a result of interaction is directly proportional to the resultant of all forces acting on the body, and inversely proportional to the mass of the body (). 3rd law: bodies act on each other by forces of the same nature, equal in magnitude and opposite in direction (). Limits of applicability of N.z.: for material points or progressively moving bodies, for speeds much less than the speed of light in vacuum, only in inertial frames.

RELATIVITY PRINCIPLE- one of the postulates, stating that in any all physical (mechanical, electromagnetic, etc.) phenomena under the same conditions proceed in the same way. Is a generalization Galileo principle of relativity on all physical phenomena (except gravity).

RELATIVITY THEORY- physical theory of space and time (special relativity theory, SRT), as well as gravitation (general relativity theory, GRT). SRT is based on the invariance (constancy) of the speed of light in vacuum with respect to inertial frames of reference. GR - the relativistic theory of gravitation - is based on the generalization of the principles of SRT to the case of non-inertial frames of reference and to equivalence principle.

SOUND REFLECTION- the process of returning a sound wave when it meets the interface between two media having different density and compressibility, back to the original medium. One of the manifestations of o.z. - echo.

REFLECTION OF WAVES LAW- the incident beam, the reflected beam and the perpendicular raised to the point of incidence of the beam lie in the same plane, and the angle of incidence is equal to the angle of refraction. The law is valid for mirror reflection.

FALLING BODIES– the process of motion of bodies in a gravitational field with an initial velocity equal to zero. The idealized process of falling only under the action of gravity (without taking into account the resistance of the medium) in a uniform gravitational field is called. free fall (cf. ).

The minimum speed at which a spacecraft in the gravitational field of the Earth can become an artificial satellite of the Earth and move in a circular orbit: , where G is the gravitational constant, M is the mass of the earth, R is the distance from the center of the Earth to the spacecraft. At the surface of the earth V=7.91 km/s.

MOVING– 1. A vector connecting the start and end points of the trajectory. 2. Vector physical quantity introduced to describe the change in the position of a material point relative to the selected reference systems for some period of time. The SI unit is the meter. In the general case, it is equal to the change in the radius vector of the point.

PERIOD- the smallest period of time after which the values ​​of physical quantities characterizing a given periodic process are repeated (for example, the period of oscillations).

SHOULDER FORCE- a value equal to the shortest distance from a given point (center) to the line of action of the force. Used in the calculation moment of force, moment of momentum etc.

LIFTING FORCE- component of the total pressure force of a liquid or gaseous medium on a body moving in it. When moving horizontally, the body is directed vertically upwards.

TRANSVERSE WAVE- a wave propagating in a direction perpendicular to the plane in which the particles of the medium oscillate (for an elastic wave) or in which the vectors of electric intensity and magnetic induction are located (for an electromagnetic wave). Wed longitudinal wave.

TRANSLATION- one of the simplest types of motion of a rigid body, in which a segment connecting two arbitrary points of a rigid body moves parallel to itself. In this case, all points of the rigid body describe the same trajectories and at each moment of time have the same speeds and accelerations.

POTENTIAL ENERGY- part of the energy of a mechanical system, depending on the relative position of the particles of the system and their position in the external force field. The value of P.e. depends on choice reference systems. Wed kinetic energy.

LONGITUDINAL WAVE- a wave in which vibrations occur in the direction of its propagation. Wed transverse wave.

- a physical quantity equal to the change in the mechanical energy of the body due to the action of a force: . M.r. constant force () is equal to: , where α is the angle between the direction of the force vector and the displacement vector. Unit in SI - joule.

EQUILIBRIUM mechanical system - the state of a mechanical system under the action of external forces, in which all its points are at rest relative to the reference frame under consideration. It takes place in the case when all the forces acting on the system and the moments of forces are balanced. There are stable (with small deviations the body returns to the equilibrium position), unstable and indifferent equilibrium. In a position of stable equilibrium potential energy body is minimal.

RESULTING FORCE- force, in its action on a solid body, is completely equivalent to the considered system of forces applied to the body. A system of forces has a resultant only if there is a point for it, relative to which the main torque system is zero. R. is equal to the geometric sum of all the forces of the system and is applied at the center of reduction, that is, the point of intersection of the lines of action of all forces.

UNIFORM MOVEMENT- a model of the movement of a material point or the translational movement of a rigid body, in which they cover the same distances for any arbitrarily small intervals of time. In this case, the velocity modulus remains constant, and the trajectory is curvilinear. Wed uniform rectilinear motion. Rotational motion is called uniform if it is performed with a constant angular velocity around the fixed axis.

UNIFORM RECTILINEAR MOVEMENT- a model of the movement of a material point or the translational movement of a rigid body, in which they make the same movements for any arbitrarily small intervals of time. In this case, the value of the velocity vector does not change with time. EQUI-VARIABLE MOVEMENT (uniformly accelerated) is a model of motion of a material point or translational motion of a rigid body, in which the speed changes in the same way for any arbitrarily small time intervals, i.e. acceleration remains unchanged. If the velocity change vector (and, accordingly, the acceleration vector) is constant, then R.d will also be rectilinear.

UNIFORMLY ACCELERATED MOTION- 1) the same as uniform motion; 2) a special case of uniformly variable motion, in which the speed modulus increases (for this, the acceleration vector and the initial speed must be oppositely directed). The reverse case is called uniformly slow motion.

RADIUS VECTOR points - a vector directed to some point in space from a fixed point, which is taken as the origin of coordinates in the selected reference system). The coordinates of the radius vector are the same as the coordinates of the point.

RESONANCE- the phenomenon of a more or less sharp increase in the amplitude of steady state forced vibrations when the frequency of the external action approaches the natural frequency of the system.

RESONATOR- a system (a body or a special device) in which resonance can occur. Examples of R.: tuning fork, air cavity (acoustic R.), oscillatory circuit (electric resonator).

RELATIVISTIC MECHANICS- mechanics of bodies moving at speeds close to speed of light in a vacuum. Laws of R.m. comply relativity theory and are valid at any velocities of bodies, up to velocities arbitrarily close to the speed of light, while Newtonian mechanics (see ) is valid only at low velocities ( V << c ). see also classical mechanics.

FREE FALL- cm. falling bodies.

PHASE SHIFT- phase difference of variable physical quantities that change according to a sinusoidal law with the same frequency. Measured in radians.

FORCE- a vector physical quantity equal to the product of the body mass and the acceleration imparted by this force. It is used to describe the mechanical impact on a given body from other bodies, leading to a change in the nature of the movement of the body or its deformation. Unit in SI - newton.

THE POWER OF SOUND- the same as .

GRAVITY- the force with which the body is attracted to the Earth (or another planet) near its surface. S.t. body with mass m is expressed by the formula: F strand =mg, where g - , depending on the geographical latitude of the place and its height above sea level.

ELASTIC FORCE- the force acting from the side of the deformed body on the bodies in contact with it and directed in the direction opposite to the movement of parts of the body during its deformation.

REFERENCE SYSTEM- a mental model, which is a combination of a reference body, an associated coordinate system and a method of measuring time. In physics, they mainly use inertial reference systems.

SPEED- one of the main quantities used to describe the motion of a material point (body). S. (instantaneous speed) - a vector quantity equal to the limit of the ratio of the movement of a point to the time interval during which this movement occurred, with an unlimited decrease in the latter. S. is directed tangentially to the trajectory of the body. The unit of C. in SI is the meter per second ( m/s).

SOUND SPEED- speed of propagation of sound waves in the medium. In gases s.z. less than in liquids, and less in liquids than in solids. In the air under normal conditions s.z. 330 m/s, in water - 1500 m/s, in tv. bodies 2000 - 6000 m/s.

SPEED OF UNIFORM RECTIOLINEAR MOVEMENT is a vector physical quantity equal to the ratio of displacement to the time interval during which this displacement occurred.

SPEED ANGULAR- cm. .

SPEED PHASE- a physical quantity equal to the product of the wavelength and the frequency. The speed at which the phase of a monochromatic sine wave propagates in space.

COMPOSITION OF FORCES- finding the geometric sum of forces by successive application of the parallelogram rule for adding vectors. For forces applied at one point S.s. leads to finding their resultant.

OWN VIBRATIONS, free vibrations - vibrations that occur in vibrational system, which is not subjected to variable external influences, due to any initial deviation of this system from the state of stable equilibrium. In real macroscopic systems, due to energy loss, the r.m.s. always fade out.

COMMUNICATING VESSELS- Vessels connected to each other at the bottom. A homogeneous liquid in communicating vessels is set at the same level, regardless of the shape of the vessels (if capillary phenomena can be neglected).

SPECIAL THEORY OF RELATIVITY- cm. .

STATICS- a section of mechanics that studies the conditions for the equilibrium of bodies under the action of forces. Wed dynamics, .

STANDING WAVES- vibrations in the resonator (string, membrane, tuning fork, etc.), characterized by alternating maxima (antinodes) and minima (nodes) of the amplitude. Occurs as a result of the interference of two running waves, the amplitude of which is the same, and the directions of propagation are mutually opposite.

TIMBRE sound - a qualitative subjective assessment of the sound emitted by a musical instrument, sound-reproducing device or voice apparatus of people and animals. It characterizes the tone of the sound and depends on which overtones accompany the main tone and what their intensity is.

TORRICHELLI FORMULA- a formula expressing the dependence of the rate of fluid outflow through a hole in the vessel wall only under the action of gravity on distance; 2) T. internal - a set of processes occurring in solid, liquid and gaseous bodies during their deformation, leading to irreversible dissipation of mechanical energy, i.e. to its transformation into internal energy. Internal t. in liquids and gases called. viscosity .

THIRD SPACE VELOCITY- the minimum speed required for a spacecraft launched from Earth to leave the solar system. At the surface of the Earth T. to. is equal to 16.67 km/s. Wed first space velocity, second space velocity.

GRAVITY- mutual attraction of any two bodies, due to the presence of their masses. For two material points is valid . T. determines the orbits of the planets (see. Kepler's laws), balance figures of celestial bodies, tide lines, etc. The modern theory of t. is the general theory of relativity. Cm. .

ANGULAR VELOCITY- vector quantity used to describe the rotational motion of a rigid body and directed along the axis of rotation according to the rule of the right screw. W.s. is equal to the limit of the ratio of the angle of rotation of the radius vector (angular displacement) to the time interval during which this rotation occurred, with an unlimited decrease in the latter. With a uniform motion of a point along a circle - a physical quantity equal to the ratio of the angle of rotation of the radius vector to the time interval during which this rotation occurred. Unit in SI - rad/s. Cm. speed.

ELASTIC WAVES- mechanical disturbances (deformations) propagating in an elastic medium. In liquids and gases, only longitudinal waveforms can be formed, at which the medium experiences only compression (tensile) deformation and the particles of the medium oscillate along the direction of wave propagation. In solids, both longitudinal and transverse waveforms arise. At transverse w.v. the medium experiences shear deformation, and the particles of the medium oscillate in directions perpendicular to the direction of wave propagation.

ELASTICITY- the property of bodies to restore their shape and volume (solid bodies), or only volume (liquid and gaseous bodies) after the termination of the forces or other causes that caused the deformation of the body. For elastic deformations of solids, . It is caused by the interaction and thermal motion of body particles.

EQUATION OF MOTION material point - the law of change in time of the coordinates of a material point when it moves in space.

ACCELERATION- a vector quantity used to describe the motion of a material point, and equal to the limit of the ratio of the velocity change vector to the time interval during which this change occurred, with an unlimited decrease in the latter. At equally variable(uniformly accelerated) rectilinear motion V. is equal to the ratio of the velocity change vector to the corresponding time interval. In curvilinear motion, it is composed of a tangent (describes the change in the velocity modulus) and normal(describes the change in direction of speed) y. Unit in SI - m/s 2.

ACCELERATION OF GRAVITY- acceleration imparted to a free material point gravity. Depends on the geographical latitude of the place and its height above sea level. Standard (normal) value g \u003d 9.80665 m / s 2.

Physical quantity used to describe the state of a periodic oscillatory process at each moment of time: , where ω - angular frequency, φ 0 - the value of the phase at the initial moment of time (initial phase). It is expressed in angular units (eg radians) or fractions of the oscillation period.

FRAGILITY- the ability of solids to collapse under mechanical stress after slight plastic deformation. Wed plastic.

CENTER OF MASS, the center of inertia is a geometric point that moves in the same way as a material point with a mass equal to the mass of the entire system of bodies would move under the action of the resultant of all external forces applied to this system. Position C.m. is determined by the distribution of masses within the system of bodies.

CENTER OF GRAVITY- point of intersection of lines of action gravity, acting on this body at any of its positions in space. For homogeneous bodies with a center of symmetry (ball, cube, etc.), the center of gravity is located at the center of symmetry. C.t. rigid body coincides with the position of its center of mass.

is the force imparting normal (centripetal) acceleration to the material point. , where m- mass of a material point, V- his speed, R- radius of curvature of the trajectory. Directed towards the center of curvature of the trajectory. The role of centripetal can be performed by central forces (the magnitude of which is proportional to the square of the distance), the Lorentz force, as well as the resultants of several forces.

CENTRIPETAL ACCELERATION- cm. .

CYCLIC FREQUENCY- cm. .

ROTATION FREQUENCY- a physical quantity equal to the ratio of the number of complete revolutions made by the body to the time interval for which they are completed. Used to describe rotational motion. Unit in SI - from -1 .

FREQUENCY- a physical quantity equal to the ratio of the number of complete oscillations performed by the body to the time interval for which they are completed. It is used to describe the oscillatory process. Inversely proportional to the period of oscillation. Unit in SI - Hertz.

ECHO- a wave reflected from some obstacle and received by an observer (receiver). Radio echo is used in radar, sound echo in sonar.

From the school bench, probably, everyone remembers what is called the mechanical movement of the body. If not, then in this article we will try not only to recall this term, but also to update the basic knowledge from the course of physics, or rather from the section "Classical Mechanics". Examples will also be shown that this concept is used not only in a certain discipline, but also in other sciences.

Mechanics

First, let's look at what this concept means. Mechanics is a section in physics that studies the movement of various bodies, the interaction between them, as well as the influence of third forces and phenomena on these bodies. The movement of a car on a highway, a soccer ball kicked into the goal, going to - all this is studied precisely by this discipline. Usually, when using the term "Mechanics", they mean "Classical mechanics". What it is, we will discuss with you below.

Classical mechanics is divided into three major sections.

1. Kinematics - it studies the movement of bodies without considering the question, why do they move? Here we are interested in such quantities as path, trajectory, displacement, speed.
2. The second section is dynamics. It studies the causes of motion, in terms of such concepts as work, force, mass, pressure, momentum, energy.
3. And the third section, the smallest one, studies such a state as equilibrium. It is divided into two parts. One illuminates the equilibrium of solids, and the second - liquids and gases.

Very often, classical mechanics is called Newtonian, because it is based on Newton's three laws.

Newton's three laws

They were first stated by Isaac Newton in 1687.

1. The first law says about the inertia of the body. This property, in which the direction and speed of movement of a material point is preserved, if no external forces act on it.
2. The second law states that the body, acquiring acceleration, coincides with this acceleration in direction, but becomes dependent on its mass.
3. The third law states that the force of action is always equal to the force of reaction.

All three laws are axioms. In other words, these are postulates that do not require proof.

What is called mechanical movement

This is a change in the position of a body in space relative to other bodies over time. In this case, material points interact according to the laws of mechanics.

It is divided into several types:

• The movement of a material point is measured by finding its coordinates and tracking changes in coordinates over time. To find these indicators means to calculate the values ​​along the abscissa and ordinate axes. The study of this is done by the kinematics of a point, which operates with such concepts as trajectory, displacement, acceleration, speed. The movement of the object in this case can be rectilinear and curvilinear.
• The motion of a rigid body consists of the displacement of some point, taken as a basis, and rotational motion around it. Studied by the kinematics of solids. The movement can be translational, that is, there is no rotation around a given point, and the whole body moves uniformly, as well as flat - if the whole body moves parallel to the plane.
• There is also the movement of a continuous medium. This is the movement of a large number of points connected only by some field or area. In view of the multitude of moving bodies (or material points), one coordinate system is not enough here. Therefore, how many bodies, so many coordinate systems. An example of this is a wave on the sea. It is continuous, but consists of a large number of individual points on a set of coordinate systems. So it turns out that the movement of the wave is the movement of a continuous medium.

Relativity of motion

There is also such a concept in mechanics as the relativity of motion. This is the influence of any frame of reference on mechanical movement. What does it mean? The reference system is the coordinate system plus the hours for Simply put, it's the abscissa and ordinate axes combined with minutes. By means of such a system, it is determined for what period of time a material point has traveled a given distance. In other words, it has moved relative to the coordinate axis or other bodies.

Reference systems can be: comoving, inertial and non-inertial. Let's explain:

• Inertial CO is a system where the bodies, producing what is called the mechanical movement of a material point, do it rectilinearly and uniformly, or are at rest at all.
• Accordingly, a non-inertial CO is a system moving with acceleration or turning with respect to the first CO.
• The accompanying CO is a system that, together with a material point, performs what is called the mechanical movement of the body. In other words, where and with what speed the object moves, the given CO also moves with it.

Material point

Why is the concept of "body" sometimes used, and sometimes - "material point"? The second case is indicated when the dimensions of the object itself can be neglected. That is, such parameters as mass, volume, etc., do not matter for solving the problem that has arisen. For example, if the goal is to find out how fast a pedestrian is moving relative to the planet Earth, then the height and weight of the pedestrian can be neglected. It is a material point. The mechanical movement of this object does not depend on its parameters.

Used concepts and quantities of mechanical movement

In mechanics, they operate with various quantities, with the help of which parameters are set, the condition of problems is written, and a solution is found. Let's list them.

• A change in the location of a body (or a material point) relative to space (or a coordinate system) over time is called displacement. The mechanical movement of a body (material point), in fact, is a synonym for the concept of "displacement". It's just that the second concept is used in kinematics, and the first - in dynamics. The difference between these subsections has been explained above.
• A trajectory is a line along which a body (material point) performs what is called a mechanical movement. Its length is called the path.
• Speed ​​- movement of any material point (body), relative to a given reporting system. The definition of the reporting system was also given above.

The unknown quantities used to determine mechanical motion are found in problems using the formula: S=U*T, where "S" is distance, "U" is speed, and "T" is time.

From the history

The very concept of "classical mechanics" appeared in antiquity, and prompted construction to develop at a rapid pace. Archimedes formulated and described the theorem on the addition of parallel forces, introduced the concept of "center of gravity". This is how static started.

Thanks to Galileo, "Dynamics" began to develop in the 17th century. The law of inertia and the principle of relativity are his merit.

Isaac Newton, as mentioned above, introduced three laws that formed the basis of Newtonian mechanics. He also discovered the law of universal gravitation. Thus the foundations of classical mechanics were laid.

Non-classical mechanics

With the development of physics as a science, and with the advent of great opportunities in the fields of astronomy, chemistry, mathematics and other things, classical mechanics gradually became not the main, but one of the many sciences in demand. When they began to actively introduce and operate with such concepts as the speed of light, quantum field theory, and so on, the laws underlying "Mechanics" began to be lacking.

Quantum mechanics is a branch of physics that deals with the study of ultra-small bodies (material points) in the form of atoms, molecules, electrons and photons. This discipline describes very well the properties of ultra-small particles. In addition, it predicts their behavior in a given situation, as well as depending on the impact. The predictions made by quantum mechanics can be very different from the assumptions of classical mechanics, since the latter is not able to describe all the phenomena and processes occurring at the level of molecules, atoms, and other things - very small and invisible to the naked eye.

Relativistic mechanics is a branch of physics that studies processes, phenomena, and laws at speeds comparable to the speed of light. All events studied by this discipline occur in four-dimensional space, in contrast to the "classical" - three-dimensional. That is, we add one more indicator to the height, width and length - time.

What is another definition of mechanical motion

We have considered only the basic concepts related to physics. But the term itself is used not only in mechanics, whether classical or non-classical.

In a science called "Socio-economic statistics" the definition of the mechanical movement of the population is given as migration. In other words, this is the movement of people over long distances, for example, to neighboring countries or to neighboring continents in order to change their place of residence. The reasons for such a displacement can be both the inability to continue living in one's own territory due to natural disasters, for example, constant floods or drought, economic and social problems in one's own state, or the intervention of external forces, for example, war.

This article discusses what is called mechanical movement. Examples are given not only from physics, but also from other sciences. This indicates that the term is ambiguous.

Mechanics is the science of moving bodies and the interactions between them during movement. At the same time, attention is paid to those interactions, as a result of which the movement has changed or the bodies have been deformed. In the article we will tell you about what mechanics is.

Mechanics can be quantum, applied (technical) and theoretical.

1. What is quantum mechanics? This is a branch of physics that describes physical phenomena and processes, the actions of which are comparable to the value of Planck's constant.
2. What is technical mechanics? This is a science that reveals the principle of operation and arrangement of mechanisms.
3. What is theoretical mechanics? It is the science and movement of bodies and the general laws of motion.

Mechanics studies the movement of all kinds of machines and mechanisms, aircraft and celestial bodies, oceanic and atmospheric currents, the behavior of plasma, the deformation of bodies, the movement of gases and liquids in natural conditions and technical systems, a polarizing or magnetizing medium in electric and magnetic fields, the stability and strength of technical and building structures, the movement of air and blood through the vessels through the respiratory tract.

Newton's law lies at the foundations, with the help of it they describe the movement of bodies with small velocities compared to the speed of light.

In mechanics, there are the following sections:

• kinematics (about the geometric properties of moving bodies without taking into account their mass and acting forces);
• statics (about finding bodies in balance using external influences);
• dynamics (about moving bodies under the influence of force).

In mechanics, there are concepts that reflect the properties of bodies:

• a material point (a body whose dimensions can be ignored);
• absolutely rigid body (a body in which the distance between any points is constant);
• a continuous medium (a body whose molecular structure is neglected).

If the rotation of the body with respect to the center of mass under the conditions of the problem under consideration can be neglected, or if it moves forward, the body is equated to a material point. If the deformation of the body is not taken into account, then it must be considered absolutely non-deformable. Gases, liquids and deformable bodies can be considered as solid media in which particles continuously fill the entire volume of the medium. In this case, when studying the movement of the medium, the apparatus of higher mathematics is used, which is used for continuous functions. From the fundamental laws of nature - the laws of conservation of momentum, energy and mass, equations follow that describe the behavior of a continuous medium. The mechanics of continuous media contains a number of independent sections - aero- and hydrodynamics, the theory of elasticity and plasticity, gas dynamics and magnetohydrodynamics, dynamics of the atmosphere and water surface, physical and chemical mechanics of materials, mechanics of composites, biomechanics, space hydroaeromechanics.

Now you know what mechanics is!