What is a mechanical movement. Criteria for replacement of body material

Mechanical movement is considered for material point I.for solid body.

Motion material point

Protective traffic absolutely solid body is mechanical movement, in the process of which any cut line, associated with this body, is always parallel to yourself at any time.

If you mentally connect the direct two dots of the solid body, then the resulting segment will always be parallel in the process of translational movement.

With progressive movement, all points of the body move equally. That is, they pass the same distance for the same time intervals and move in one direction.

Examples of the translational movement: the movement of the cabin of the elevator, a cup of mechanical scales, slicing, rushing from the mountain, bicycle pedals, railway platforms, engine pistons with respect to cylinders.

Rotary traffic

With rotational motion all points physical body Moving around the circles. All these circles lie in planes parallel to each other. And all points of rotation centers are located on one fixed direct, which is called axis of rotation. Circle, which are described by points, lie in parallel planes. And these planes are perpendicular to the axis of rotation.

Rotary traffic It is found very often. So, the movement of points on the wheel rim is an example of a rotational movement. Rotational motion describes the fan propeller and others.

The rotational movement characterizes the following physical quantities: angular speed of rotation, rotational period, rotational speed, line speed Points.

Angular speed The bodies with uniform rotation are called the value equal to the ratio of the angle by the time interval during which this turn occurred.

The time for which the body passes one full turn is called rotation period (T).

The number of revolutions that the body performs per unit of time is called rotation frequency (F).

The frequency of rotation and the period are related by the relation T \u003d 1 / F.

If the point is at a distance of R from the center of rotation, then its linear speed is determined by the formula:

What is a mechanical movement and what is it characterized? What parameters are introduced to understand this type of movement? What terms do you most often operate? In this article, we will reply to these questions, consider mechanical movement from different points of view, we give examples and we will deal with the solution of tasks from the physics of the relevant theme.

Basic concepts

Since the school bench, we are learning that the mechanical movement is a change in the position of the body at any time of time relative to other bodies of the system. In fact, everything is so. Let's take an ordinary house in which we are, for zero coordinate system. Imagine visually that the house will be the beginning of the coordinates, and an abscissa axis and the ordinate axis will go out in any directions.

In this case, our movement within the house, as well as beyond its limits, will clearly demonstrate the mechanical movement of the body in the reference system. Imagine that the point moves through the coordinate system, at each moment of time changing its coordinate relative to both the abscissa axis and relative to the axis of the ordinate. Everything will be simple and understandable.

Characteristic of mechanical traffic

What could be this type of movement? We will not deepen in the debris of physics. Consider the simplest cases when the material point moves. It is divided into rectilinear movement, as well as curvilinear movement. In principle, everything should be clear from the name, but let's talk about it more precisely in case.

The straightforward movement of the material point will be called such a movement, which is carried out along a trajectory, having a straight line. Well, for example, the car rides right under the road, which has no turns. Or on the site of this road. That will be a straight movement. In this case, it can be uniform or equal.

The curvilinear movement of the material point will be called such a movement, which is carried out along the trajectory, which does not have the kind of straight line. The trajectory can be broken line as well closed line. That is, a circular trajectory, ellipsoid and so on.

Mechanical movement of the population

This type of movement does not have almost absolutely nothing to do with physics. Although, depending on which point of view, we perceive it. What is generally called mechanical movement of the population? They are called the resettlement of individuals, which occurs as a result of migration processes. It can be both external and internal migration. By duration, the mechanical movement of the population is divided into permanent and temporary (plus pendulum and seasonal).

If we consider this process from a physical point of view, it is possible to say only one thing: this movement will perfectly demonstrate the movement of material points in the reference system associated with our planet - the Earth.

Uniform mechanical movement

As clearly out of the name, this is a type of movement at which the body speed has a certain value stored constant by module. In other words, the body speed, which moves evenly, does not change. IN real life We practically cannot notice the ideal examples of uniform mechanical movement. You can completely argue, they say, you can go by car at a speed of 60 kilometers per hour. Yes, definitely speedometer vehicle It can demonstrate a similar meaning, but this does not mean that in fact the speed of the car will be equal to sixty kilometers per hour.

What is it about? As we know, firstly, all measuring instruments have a definite error. Rulers, scales, mechanical and electronic devices - everyone has a certain error, inaccuracy. You can make sure of this by taking a dozen lines and attaching them one to another. After that, you can notice some discrepancies between millimeter marks and their application.

The same applies to the speedometer. It has a certain error. The devices have inaccuracy numerically equal to half of the division price. In cars, the inaccuracy of the speedometer will be 10 kilometers per hour. That is why at a certain point it is impossible to say for sure that we are moving with one or another speed. The second factor that will make inaccuracy will be the forces acting on the car. But the forces are inextricably linked to acceleration, so we will talk on this topic a little later.

A very often uniform movement is found in mathematical tasks than physical. There are motorcyclists, cargo and cars Moving at the same speed equal to the module at different points in time.

Equal asked movement

In physics, such a type of movement occurs quite often. Even in the tasks of the part "A" both the 9th and 11th grade, there are tasks in which you need to be able to perform operations with acceleration. For example, "A-1", where the body motion schedule is drawn in the coordinate axes and it is required to calculate how the distance the car passed for one or another time. Moreover, one of the gaps can demonstrate a uniform movement, while on the second it is necessary to calculate the acceleration first and only then count the distance traveled.

How to find out that the movement is equivalent? Typically, information about this is supplied directly. That is, there is either a numerical specification of acceleration, or parameters (time, speed change, distance), which allow us to determine the acceleration. It should be noted that acceleration is a vector value. So it may be not only positive, but also negative. In the first case, we will observe the acceleration of the body, in the second - its braking.

But it happens that information about the type of movement is taught in a slightly secretive, if you can call it, form. For example, it is said that nothing works on the body or the amount of all forces is zero. Well, in this case you need to clearly understand that it is about uniform motion either about the peace of the body in a specific coordinate system. If you remember Newton's second law (which states that the sum of all forces is nothing but a product of body weight to accelerate, reported under the action of the relevant forces), it is easy to notice one interesting thing: if the amount of strength is zero, then The product of the mass on acceleration will also be zero.

Output

But after all, we have a permanent amount, and she cannot be zero. In this case, it will be logical that in the absence of an action of external forces (or with their compensated action) there is no acceleration of the body. It means that it either rests, or moves at a constant speed.

Formula of equivalent movement

Sometimes found in scientific literature The approach, according to which light formulas first is given, and then, taking into account some factors, they are complicated. We will do the opposite, namely, consider at first an equilibrium movement. The formula according to which the distance passed is calculated as follows: S \u003d V0T + AT ^ 2/2. Here, V0 is the initial velocity of the body, A - acceleration (may be negative, then the sign + will change in the formula for -), and T - the time passed from the beginning of the movement before stopping the body.

Formula of uniform motion

If we talk about a uniform movement, we remember that at the same time the acceleration is zero (a \u003d 0). We substitute zero in the formula and get: S \u003d V0T. But after all, the speed on the whole site of the path is constant, if we say rudely, that is, you will have to neglect the forces acting on the body. As, by the way, in kinematics is practiced everywhere, since kinematics does not study the causes of the movement, the dynamics are engaged. So, if the speed is constant on the entire site of the path, then its initial value coincides with any intermediate, as well as the final. Therefore, the distance formula will look like this: S \u003d VT. That's all.

Ticket number 1.

Mechanical movement. The relativity of motion. Reference system. Material point. Trajectory. Path and movement. Instant speed. Acceleration. Uniform and equivalent movement.

The mechanical movement of the body is called a change in its position in space relative to other bodies over time.

The trajectory of the body movement, traveled path and movement depend on the selection of the reference system. In other words, mechanical movement relative. The coordinate system, the reference body with which it is connected, and the indication of the start of the time is formed the reference system.

The body, the sizes of which in these conditions of movement can be neglected, called a material point.

The line on which the point of the body is moving is called the trajectory of movement. The length of the trajectory is called the passage passed.

The vector connecting the initial and endpoint of the trajectory is called moving.

Instant speed of the progressive body movement at time t called the ratio of very small movement s to a small period of time for which it happened:

υ \u003d S / T υ \u003d 1 m / 1 s \u003d 1 m / s

Movement with a constant modulo and direction is called uniform straightforward movement.

When changing the body velocity, the concept of body acceleration is introduced.

The acceleration is called a vector value equal to the ratio of a very small change in the velocity vector to a small period of time for which this change occurred:

a \u003d υ / t a \u003d 1 m / s 2

It is equal to the movement with an acceleration, permanent module and direction:

What force is the magnetic field with B \u003d 1.5 T on the conductor length L \u003d 0.03 m, located perpendicular to the magnetic field. Current strength i \u003d 2 a

Ticket number 2.

Interaction tel. Force. The second law of Newton.

The reason for changing the speed of the body movement is always its interaction with other bodies. After turning off the engine, the car gradually slows down and stops. The main reason for changing the velocity of the car is the interaction of its wheels with a road surface. In physics, for the quantitative expression of one body, the concept of "power" is introduced to another. Examples of forces:
forces of elasticity, gravity, gravity, etc.

Power is a vector value, it is denoted by symbol F. For the direction of the strength vector, the direction of the body acceleration vector is taken to which the force acts. In the SI system:

F \u003d 1 H \u003d 1 kg * m / s 2

2 Law Newton:

The force acting on the body is equal to the product of body mass on the acceleration reported by this force:

The meaning of the law is that the force acting on the body determines the change in the body velocity, and not the speed of the body.

Laboratory work "Measurement of the refractive index of glass"

Ticket number 3.

Body impetus. The law of preserving the impulse. The manifestation of the law of preserving the impulse in nature and its use in the technique.

There is a physical amount equally changing in all bodies under the action of the same forces if the time of force is equally.

The value equal to the mass of the body mass on the speed of its movement is called a body pulse or the amount of movement.

Changing the body pulse is equal to a force impulse that causes this change.

The physical value equal to the work of force F at time t of its action is called a power pulse.

The body pulse is the quantitative characteristic of the progressive movement of tel. Unit of body pulse measurement is the value: kg * m / s.

Pulse conservation law:

In a closed system, the geometric sum of pulses of bodies remains constant for any interactions of the bodies of this system among themselves:

m 1 υ 1 + m 2 υ 2 \u003d m 1 υ 1 i + m 2 υ 2 I

where 12, υ 12 I - the velocities of the first and second body before and after the interaction.

The system of bodies that do not interact with other bodies that are not included in this system is called a closed system.

The law of preserving the impulse is manifested in inertial reference systems (i.e., in those in which the body in the absence of external influences is moving straight and evenly). This law is used in the technique: jet engine. When combustion of fuel, the gases heated to a high temperature is thrown out of the rocket nozzle at speed. The rocket begins to move as a result of this interaction and in accordance with this law.

The battery with EDC 6 V and internal resistance r \u003d 0.1 ohms feeds the outer chain with R \u003d 11.9 Ohm .. How much heat is extended for 10 minutes in the entire chain?

Ticket number 4.

The law of global gravity. Gravity. Body weight. Weightlessness.

Newton proved that the movement and interaction of the planets of the solar system occurs under the action of the force of attraction directed towards the Sun and decreasing inversely proportional to the square of the distance from it. All bodies in the Universe mutually attract each other.

The force of mutual attraction between the bodies in the Universe, Newton called the power of global gravity. In 1682, Newton opened the world of global gravity:

All bodies are attracted to each other. The world's strength is directly proportional to the mass of mass bodies and is inversely proportional to the square of the distance between them:

F \u003d g * m 1 * m 2 / r 2

G-gravitational constant.

The force of attraction, acting on the part of the earth for all bodies, is called force of gravity:

This power decreases inversely proportional to the square of the distance from the center of the Earth.

The concept of body weight is widely used in the technique and everyday life.

Weight body call the force with which the body due to its attraction to the ground acts on the horizontal support or suspension.

Body weight on a fixed or evenly moving horizontal support equal to power Severity, but they are attached to different bodies.

With accelerated movement of body weight, the direction of acceleration of which coincides with the direction of acceleration of free fall, less than the weight of the rest of the body.

If the body together with the support freely falls and the acceleration of the body is equal to the acceleration of the free fall, and their directions coincides, the body weight disappears. This phenomenon received Nazainlessness:

A \u003d g p \u003d 0 weightlessness

At what temperature, the internal energy is 20 kg. Argon will be 1.25 * 10 6 J?

Ticket number 5.

Transformation of energy in mechanical oscillations. Free and forced oscillations. Resonance.

In nature and the technique there is a form of mechanical movement-oscillation.

Mechanical oscillation is called the movement of the body, repeating exactly or approximately after the same intervals.

Forces acting between bodies inside the system are called internal. Forces acting from outside the system, the bodies of this system are called external.

Free oscillations call fluctuations arising under the influence of domestic forces. Oscillations under the action of external periodically changing forces are called forced.

With the deviation of the pendulum from the equilibrium position, its potential energy increases, because Increases the distance from the surface of the Earth. When moving to the position of equilibrium, the speed of the pendulum increases, its kinetic energy increases by reducing the stock potential, as a result of a decrease in distance from the surface of the Earth. In the equilibrium position, the kinetic energy has the maximum value, and the potential is minimal. After passing the position of the equilibrium, the conversion of kinetic energy into the potential, the speed of the pendulum decreases and at maximum deviation becomes zero. Thus, the periodic transformation of energy occurs. But because When moving, the bodies interact with other bodies, so part of the mechanical energy turns into the internal energy of the thermal motion of atoms and molecules. The amplitude of oscillations will decrease and after some time the pendulum will stop. Free oscillations are always fading.

In the system, when exciting oscillations under the action of periodically changing external power The amplitude, first, gradually increases. After a while, oscillations are installed with a constant amplitude and with a period equal to the period of external force.

The amplitude also depends on the frequency of change in force. Provided when the frequency of the ν ν coincides with its own frequency of the system ν 0, the amplitude has the maximum value.

The resonance is a sharp increase in the amplitude of the forced oscillations when the frequency is approached by the frequency of the external force acting on the system, to the frequency of free oscillations. The less friction in the system, the more clearly resonance (in fig. Curve No. 1).

Laboratory work "Determination of the focal length of collecting lenses."

Ticket number 6.

An experimental substantiation of the basic provisions of the molecular-kinetic theory of the structure of the substance. Mass and size of molecules. Permanent Avogadro.

In the early 19th century, English scientist Dalton showed that many of nature phenomena can be explained using the molecular structure of the substance. By the beginning of the 20th century, the molecular-kinetic theory of the substance was finally created and confirmed by experiments. The main positions of MKT:

substances consist of molecules between which there are intermolecular intervals.

Molecules are continuous and chaotically moving.

At short distances between molecules and atoms, both the forces of attraction and the repulsion force are operated. The nature of these forces is electromagnetic.

Chaotic movement is also called thermal, because It depends on temperature.

Experienced justification:

The fact that substances consist of molecules was proven by snapshots made by electronic microscope. The photographs show the location of molecules.

The fact that molecules are continuously moving, proven by the experience of Brown. He watched in 1827, how the grains are moving in water. I could not explain. Brownian movement - the movement of grains, caused by blows of chaotic water molecules. And another phenomenon of nature - diffusion, proves the continuous movement of molecules. Diffusion is the phenomenon of penetration of the molecules of a substance in the molecules of another substance. Even in solid bodies, where the medley of all this Popes of penetration occurs, diffusion is still observed. For example: Golden plate lies on the lead. Are under load. After some time, the molecule of each substance will be found in a nearby touching body.

3. The fact that molecules are attracted to each other proves experience with lead cylinders. They withstand weight up to 5 kg. Diffusion also proves that molecules are interacted in solid bodies.

Between molecules simultaneously act as the repulsion strength and interaction. By nature, they are magnetic. In deformations in solid bodies, force shows themselves in the form of the strength of elasticity and determine the strength of the tel. These forces act at very low distances - within the size of the molecules. But it will observe the effect if the molecules are closer to the distance more of their stable equilibrium (when two types of forces are equal to the value), then the repulsion force will increase, and attraction will decrease.

Experimental studies have shown that molecules are very small. For example: the mass of the olive oil molecule M 0 \u003d 2.5 * 10 -26 kg., And the size of the molecule d \u003d 3 * 10-10 m.

The Avogadro number is the number of atoms contained in 0, 012 kg of carbon isotope 12 C. Named in honor of the Italian 19th century scientist.

N a \u003d 6,02 * 10 23 mol -1

When electrolysis, copper sulfate solution was performed

A \u003d 1.4 * 10 7 J. Define the amount of medalized copper if the voltage between the bath electrodes is U \u003d 6 B.

Ticket number 7.

Perfect gas. The main urvement of the ICT of the perfect gas. Temperature and its measurement. Absolute temperature.

In real life, studying phenomena in nature and technology, it is impossible to take into account all the factors affecting it. For this reason, it is possible to take into account the most important factor, such as the movement of molecules, and other (interaction) not to take into account. This basis introduces the phenomenon model.

Gas molecules, hitting the surface of the body or the wall of the vessel, have pressure -r. The pressure depends on the following factors:

from the kinetic energy of the movement of molecules. Than it is more, the more pressure;

the number of molecules per unit volume. What they are more, the greater the pressure.

Basic equation perfect Gaza It can be written as a formula:

P \u003d n * m 0 * υ 2/3 or p \u003d 2 * n * E / 3

Where n is the concentration of molecules in a unit of volume (n \u003d n / v), M 0 is a mass of one molecule, E is the average value of the kinetic motion of molecules, υ 2 is the average value of the square of the speed of the kinetic movement of molecules.

The pressure of the ideal gas is directly phonationally by the average kinetic energy of the translational movement of its molecules and the number of molecules in a unit of volume. Pressure is measured in Pascal P \u003d PA. Conditions close to perfect gas are created in electrovacuum lamps and devices. There is a vacuum, because Gas molecules are a hindrance - the filament of the lamp will oxidize and the braid instantly.

Temperature-value characterizing the degree of heated body. In order to measure the body temperature, the device was created - the thermometer. The reference was chosen a hydrogen thermometer, in which discharged hydrogen was used as a substance. It expands when heated is equally like oxygen, nitrogen, etc. The closed vessel with discharged hydrogen was connected to the pressure gauge (the instrument for measuring pressure) and increasing the temperature, the gas expanded, thereby changing its pressure. The pressure and temperature are linearly linked, then the pressure gauge can be determined to determine the temperature. The temperature scale installed on a hydrogen thermometer is called a Celsius scale. In 0 0 ° C, the temperature of the ice melting was adopted under normal atmospheric pressure, and for 100 0 oral boiling point of water, as well as at normal pressure 1. It is possible to otherwise construct a temperature scale. For a deeper understanding of the physical meaning of phenomena, Kelvin offered another scale - thermodynamic. Now it is called the Celvin scale. In it, it was taken -273 0 C. This value is called absolute zero - the temperature in which the translational movement of molecules is terminated. Below the temperature in nature is not found. The temperature on this scale is called an absolute temperature and is measured in Kelvin - T K.

The speed of movement of molecules depends on the temperature, therefore it is said that the temperature is a measure of the kinetic motion of molecules. With increasing temperature, the average speed of the translational movement of molecules increases.

E \u003d 3 * K * T / 2 P \u003d nkt where k-constant Boltzmann \u003d 1.38 * 10 -23 J / K

Dana electrical scheme. Determine the resistance of four conductors with the same resistance R 1-4 \u003d 4 Ohms, connected by a diagram:

Conductors 1,4-connected sequentially, and 2,3-parallel.

Find the overall resistance of the conductors 2.3:

R 23 \u003d R / n R 23 \u003d 4/2 \u003d 2 Ohm.

We find the full resistance of the entire chain:

R \u003d R 1 + R 23 + R 4 r \u003d 4 + 2 + 4 \u003d 10 ohms.

Ticket number 8.

The equation of the state of the ideal gas (the Mendeleev-Klapairone equation). Isoprocesses.

In real life, studying phenomena in nature and technology, it is impossible to take into account all the factors affecting it. For this reason, it is possible to take into account the most important factor, such as the movement of molecules, and other (interaction) not to take into account. This basis introduces the phenomenon model.

Perfect gas-model of real gas. It is gas, the dimensions of whose molecules are small compared to the volume of the vessel and they practically do not interact.

Physical quantities whose value is determined by the joint action of a huge number of molecules are called thermodynamic parameters: P, V, T.

The ideal gas is described by these parameters that are included in the Mendeleeval-Clapierone equation: PV \u003d M * R * T / M

where M is a molar mass of the substance, the R - the universal gas constant, does not depend on the nature of the gas \u003d 8.31 N * m / kmol * k, M-weight of the gas.

Isoprocess is a process in which the mass of gas and one of its parameters remain constant.

Determine the red photoeper border for metal with the operation of the output A \u003d 3.2 * 10 -19 J.

Ticket number 9.

Evaporation and condensation. Saturated and unsaturated pairs. Air humidity. Measuring air humidity.

Substances are moving from one state to others. With chaotic movement, some water molecules having a big kinetic energy leaving it. At the same time, they overcome the forces of attraction from the remaining molecules. This process is called evaporation. (see poster). But another process can also be observed when the pair molecules are returned to the liquid, such a process is called condensation. If there is a flow of air over the vessel, then it takes the steam molecules and the evaporation process is faster. The process of evaporation and with increasing fluid temperature is reduced.

If the vessel is covered with a lid, then after a while, a dynamic equilibrium is established - the number of molecules that left the liquid \u003d the number of molecules returned to the liquid.

Couples, located in dynamic equilibrium with its liquid, is called saturated. Even if we begin to compress the saturated steam at a constant temperature, initially the equilibrium will break, but then the concentration of the steam molecules is again equal, as with dynamic equilibrium.

The pressure of a saturated pair P 0 does not depend on the volume at a constant temperature.

On Earth there is a continuous form of water vapor: evaporation from water bodies, plant covers, couples exhaled by animals. But this water vapor is not saturated, because There is a movement of air masses in the atmosphere.

Humidity is the number of water vapor in the Earth's atmosphere.

Water steam - humidity- is characterized by parameters. (hereinafter see Cabinet posters and tell them).

Relative humidity can be measured by several instruments, but consider one-psychrometer. (Further on the device and measurement method, tell us on the posters).

Laboratory work "Measurement of the length of the light wave using a diffraction lattice".

Ticket number 10.

Crystal AI amorphous bodies. Elastic and plastic deformations of solid bodies.

Crystals surround us everywhere. Solid bodies All belong to crystals. But because In nature there are no single - single crystals, we do not see them. Most often substances consist of a variety of closed crystalline grains - polycrystals. At crystalline bodies, atoms are in strict and form a spatial crystal grid. As a result, they have the right external form. Examples of crystal tel: Cooking salt, snowflake, mica, graphite, etc. These bodies have certain properties - graphite writes well layers, salt breaks with flat edges, mica is separated in the equity direction. T. OB. They coincide physical properties In one direction - is called anisotropy. In fact, most often anisotropy is not observed, because The body consists of a large number of chaotic crystals, the total effect of anisotropy leads to the removal of this phenomenon. But there are other bodies that do not consist of crystals, i.e. They have no crystal lattice, they are called amorphous. They possess the properties of elastic and liquid bodies. When you hit, they osculate, at high temperatures they flow. Examples of amorphous bodies: glass, plastics, resin, rosin, sugar lollipop. They have the same physical properties in all directions - Naz. Isotropy.

The external mechanical effect on the body causes the displacement of atoms from equilibrium positions and leads to a change in the shape and volume of the body, i.e. to his deformation. The simplest types of deformation are stretching and compression. Stretching is experiencing cables of lifting cranes, cable cars, towing cables, strings of musical instruments. The walls and foundations of buildings are compressed. The deformation can be characterized by an absolute elongation Δl \u003d L 2 -L 1, where L 1 is a stretch, L 2 - after it. And the ratio of absolute elongation to the length of the sample is called relative elongation: ε \u003d ΔL / L 1. When deforming the body arise for elasticity. The physical value equal to the ratio of the module of the force of elasticity to the area of \u200b\u200bthe body cross section is called the voltage σ \u003d f / s. With small deformations, the law of the thread is performed when the deformation increases in proportion to the increase in force on the body. But only before a certain strength. If the voltage is increased and after it is removed, the size of the body is still restored by fully, this deformation is called elastic, otherwise it is called residual or plastic.

...); Does he read mechanical"Or consciously. Errors, ... requirements) is divided into about completed in meaning ...; force movements; Volume movements: Accuracy movements; smoothness movements; symmetry movements; The presence of synclosis ...

Mechanical movement Bodies call the change in its position in space relative to other bodies over time. For example, a person riding an escalator in the subway is located on the rest of the escalator itself and moves relative to the walls of the tunnel

Types of mechanical movement:

• straight and curvilinear - in the form of the trajectory;
• uniform and uneven - according to the law of movement.

Mechanical movement relatively. This manifests itself in the fact that the form of the trajectory, moving, speed and other characteristics of the body movement depends on the selection of the reference system.

The body relative to which the movement is considered, called body reference. The coordinate system, the reference body with which it is connected, and the device for the countdown of time form reference system Regarding which the body movement is considered.

Sometimes body sizes compared to the distance to it can be neglected. In these cases, the body consider material point.

Definition of body position at any time is the main task of mechanics.

Important characteristics of motion are the trajectory of the material point, movement, speed and acceleration. Line, along which the material point is moving, called trajectory . The length of the trajectory is called path (L). The unit of measurement is 1m. The vector connecting the initial and endpoint of the trajectory is called moving (). Movement Unit - 1 m..

The simplest type of movement is a uniform rectilinear movement. Movement in which the body for any equal periods of time makes the same movement, called straightforward uniform motion. Speed () - Vector physical quantity characterizing the speed of movement of the body, numerically equal to the ratio of movement over a low period of time to the magnitude of this gap. The determining speed formula has the form v \u003d S / T. Speed \u200b\u200bMeasurement Unit - m / S.. Measure speed speedometer.

The movement of the body, in which its speed changes in any time varies the same, called equalious or equally referred.

— The physical quantity characterizing the speed changes and numerically equal to the ratio of the velocity change vector per unit of time.Acceleration unit in si — m / s 2 .

equaliousIf the speed module increases. - The condition of the equal token movement. For example, overclocking vehicles, cars, trains and free drop in tel near the surface of the Earth (\u003d).

Equipment movement is called equalionedIf the speed module decreases. - the condition of the equilibrium movement.

Instant speed equal asked straight line