Ticket number 1

Equally accelerated motion is a motion in which the acceleration is constant in magnitude and direction

a = v-v0 / t-t0

a = v-v0 / t

A lens is a transparent body bounded by two spherical surfaces. If the thickness of the lens itself is small compared to the radii of curvature of the spherical surfaces, then the lens is called thin.

The power of the lens is the reciprocal of the focal length of the lens, expressed in meters.

D = 1 / F = 1 / d + 1 / f

D - Optical power of the lens

F - Focal length of the lens

D- Distance from the object to the lens

F- Distance from lens to image

Ticket 2

1) all bodies are composed of particles: atoms, molecules and ions;

particles are in continuous chaotic motion (Thermal);

Particles interact with each other through absolutely elastic collisions.

Ground states: Solid, liquid, gaseous, plasma.

Free fall is a uniformly accelerated motion with no initial velocity.

V ^ 2 = 2gh

h = gt ^ 2/2

Free fall acceleration is the acceleration imparted to a body by gravity.

g = GM / r ^ 2

Ticket number 3

Thermal motion is a process of chaotic (disordered) movement of particles that form matter.

Brownian motion is an irregular movement of microscopic visible particles of a solid suspended in a liquid or gas, caused by the thermal motion of particles of a liquid or gas.

Temperature is a physical quantity that characterizes the thermal state of bodies.

The phenomenon in which there is a mutual penetration of the molecules of one substance between the molecules of another is called diffusion.

2) Curvilinear motion is a motion whose trajectory is a curved line (for example, a circle, ellipse, hyperbola, parabola).

Uniform circular motion is the simplest example of curved motion.

l = 2πR

Ticket number 4

Mechanical movement is a change in the position of bodies in space relative to each other over time.

V = △ S / △ t

Reference body - the body relative to which the movement is observed.

A reference system is a set of a reference body, a coordinate system associated with it and a time reference system, in relation to which the motion of any bodies is considered.

2) Internal energy is the energy of movement and interaction of particles,
of which the body is made.

Internal energy depends on the temperature of the body, its state of aggregation, on chemical, atomic and nuclear reactions

△ U = Q-A

Types of heat transfer.

Convection, radiation, thermal conductivity

Ticket number 5

Newton's first law - if forces do not act on a body or their action is compensated, then this body is in a state of rest or uniform rectilinear motion.

An inertial frame of reference is a frame of reference in which all free bodies move rectilinearly and uniformly, or are at rest.

The amount of heat is the change in the internal energy of the body, which occurs as a result of heat transfer. Measured in joules.

The specific heat capacity of a substance shows how much heat is needed to change the temperature of a unit mass of a given substance by 1 ° C.

Q = c * m * (t2 - t1)

Ticket number 6

Trajectory - a line in space along which the body moves.

Moving - changing the position of a physical body in space.

Path - the length of the section of the trajectory of a material point, traversed by it in a certain time.

Inertia is a physical phenomenon of body speed conservation.

Fuel Energy - Different fuels of the same mass produce different amounts of heat when fully burned.

Specific calorific value shows how much heat will be released during complete combustion
1 kg of this fuel.

Ticket number 7

1) The force of gravity is the force of the gravitational interaction of bodies with masses. F = G * m1 * m2 / R ^ 2

The force of gravity is a manifestation of the force of universal gravity near the surface of the Earth or on its surface.

The weight of the body is the force with which the body presses on the support or pulls the suspension.

Weightlessness is a state in which the force of interaction of a body with a support (body weight), arising in connection with gravitational attraction, is negligible.

The transition of a substance from a solid to a liquid state is called melting; the temperature at which this process takes place is called the melting point. The transition of a substance from a liquid to a solid state is called solidification or crystallization. Substances solidify at the same temperature at which they melt.

Specific heat of fusion is a physical quantity that shows how much heat must be communicated to one unit of mass of a crystalline substance in an equilibrium isobaric-isothermal process in order to transfer it from a solid (crystalline) state to a liquid state.

Lambda = Q / m

Ticket number 8

Force is a vector quantity that is a measure of the mechanical action of one material body on another.

Mass, a physical quantity, is one of the main characteristics of matter, which determines its inertial and gravitational properties.

Newton's second law is that the acceleration that a body receives is directly proportional to the force applied to the body and inversely proportional to the mass of the body.

2) Condensation - the transition of a substance into a liquid or solid state from a gaseous state.

Evaporation - the process of phase transition of a substance from a liquid state to a vapor or gaseous

Saturated steam is in dynamic equilibrium with its liquid. This state is characterized by the fact that the number of molecules leaving the surface of the liquid is equal, on average, to the number of vapor molecules returning to the liquid during the same time.

Ticket number 9

Air humidity depends on the amount of water vapor contained in it.

1) Boiling is a process of intense vaporization that occurs in a liquid, both on its free surface and inside its structure.

The friction force is the force that occurs when two bodies come into contact and prevents their relative movement.

Ftr = μ Fnorm

Ticket number 10

Momentum is a vector physical quantity that is a measure of the mechanical movement of a body

a = v2-v1 / △ t

The law of conservation of momentum - the vector sum of the momenta of all bodies in the system is a constant value if the vector sum of external forces acting on the system of bodies is equal to zero.

Reactive motion is a movement that occurs when some part of the body is separated from the body at a certain speed.

The first law of temodynamics - Energy cannot be created or destroyed (the law of conservation of energy), it only passes from one type to another in various physical processes.

Steam or gas, expanding, can do work.
In this case, the internal energy of the steam is converted into mechanical energy

Ticket number 11

1) Pressure is a physical quantity that is numerically equal to the force acting per unit of surface area perpendicular to this surface.

The pressure applied to a liquid or gas is transmitted to any point in the liquid or gas equally in all directions.

Electric charge is a physical quantity that characterizes the property of particles or bodies to enter into electromagnetic force interactions.

The force of interaction of two point charges in a vacuum is directed along a straight line connecting these charges, proportional to their values ​​and inversely proportional to the square of the distance between them.

Ticket number 12

Energy - One of the main properties of matter is the measure of its movement, as well as the ability to do work.

Energy types: Kinetic, Potential, Electromagnetic

, Gravitational, Nuclear, Chemical, Thermal, Vaakuma.

The law of conservation of energy - energy cannot disappear without a trace or arise from nothing.

The second law of temodynamics is that the entropy of isolated systems in irreversible processes can only increase, and in a state of thermodynamic equilibrium it reaches a maximum.

Ticket number 13

Atmospheric pressure is the pressure of the atmosphere acting on all objects in it and the earth's surface.

A barometer is a device for measuring atmospheric pressure.

Ticket number 14

1) Electrostatic field - a field created by electric charges fixed in space and constant in time (in the absence of electric currents).

Electric field strength is a vector physical quantity that characterizes the electric field at a given point and is numerically equal to the ratio of the force (\ displaystyle (\ vec (F)),) acting on a stationary point charge placed at a given point of the field to the value of this charge.

Potential electrostatic field - a scalar value equal to the ratio of the potential energy of the charge in the field to this charge.

Ticket number 15

Ticket number 16

1) Ohm's Law - an empirical physical law that determines the relationship between the electromotive force of a source or electrical voltage with the current strength and resistance of a conductor, established in 1826, and named after its discoverer Georg Ohm.

Electrical resistance is a physical quantity that characterizes the properties of a conductor to prevent the passage of electric current. R = U / I
When the tog flows through the conductor, the stream of charged particles hits and rubs against the atoms of the conductor.
Depends on both voltage and current.

2) The devices used to transform the force and change its direction are called simple mechanisms.

Ticket number 17

The work of the current is the work of the electric field to transfer electric charges along the conductor; The work of the current in the section of the circuit is equal to the product of the current strength, voltage and time during which the work was performed.

Ticket number 18

Ticket number 19

Ticket number 20

Ticket number 21

1) Wave process (wave) is the process of propagation of oscillations in a continuous medium. Continuous medium- continuously distributed in space and having elastic properties.

A semiconductor is a material that, in terms of its conductivity, occupies an intermediate place between a conductor and a dielectric and differs from a conductor in a strong dependence of conductivity on the concentration of impurities, temperature and various types of radiation.

Ticket number 22

Ticket number 23

1) Photoeffect - the emission of electrons by a substance under the influence of light or any other electromagnetic radiation. In condensed (solid and liquid) substances, external and internal photoelectric effect is released

Einstein's formula for the photoeffect is the formula:
- expressing the quantum nature of the external photoelectric effect; and
- explaining its basic laws.

Reflections of light - the physical process of the interaction of waves or particles with a surface, a change in the direction of a wave front at the boundary of two media with different properties, in which the wave front returns to the medium from which it came

Ticket number 24

1) When a wire with a current is placed in a magnetic field, the magnetic force acting on the current carriers is transmitted to the wire. We obtain an expression for the magnetic force acting on an elementary piece of wire with a length dl in a magnetic field with induction IN.

Ticket number 25

1) If the mass of the integral nucleus is subtracted from the sum of the masses of individual particles of the nucleus, then the remaining value of Δm is called the mass defect of the given nucleus.

A nuclear reaction is the process of interaction of an atomic nucleus with another nucleus or elementary particle, accompanied by a change in the composition and structure of the nucleus. Nuclear fission, emission of elementary particles or photons can become a consequence of the interaction.

Ticket number 1

Acceleration is a quantity that characterizes the rate at which speed changes.

Variable or irregular motion is motion in which the velocity vector changes over time.

The average speed is called a value equal to the ratio of the movement of the body over a certain period of time to this period of time:

Sometimes the average speed is understood as a scalar value equal to the ratio of the path traveled by the body for a certain period of time: It is this speed that is meant when, for example, they talk about the average speed of a car in a city or the average speed of a train.

With an uneven translational motion, the speed of the body will continuously change over time. The process of changing the speed of a body is characterized by acceleration. Acceleration is a vector quantity equal to the ratio of a very small change in the velocity vector to a small time interval during which this change occurred:

If for a period of time t body from point BUT trajectory moved to point IN and its speed changed from v 1 before v 2 , then the change in speed over this time interval is equal to the difference of vectors v 2 and v 1 :

The direction of the acceleration vector coincides with the direction of the velocity change vector at very small values ​​of the time interval t, during which the speed change occurs.

If the body moves in a straight line and its speed increases, then the direction of the acceleration vector coincides with the direction of the speed vector v 2 , with decreasing velocity in absolute value, the direction of the acceleration vector is opposite to the direction of the velocity vector v 2 .

When the body moves along a curvilinear trajectory, the direction of the velocity vector changes during the movement, the acceleration vector can be directed at any angle to the velocity vector v 2 ... The simplest type of uneven motion is uniformly accelerated motion. Equally accelerated is a movement with an acceleration constant in magnitude and direction:

From the formula it follows that when expressing speed in meters per second, and time in seconds, acceleration is expressed in meters per second squared:

A meter per second squared is equal to the linearly and uniformly accelerated acceleration of a moving point, at which, in a time of 1 s, the speed of the point changes by 1 m / s. With uniformly accelerated movement with an initial speed v 0 acceleration equals

where is the speed at the moment of time. Hence, the speed of uniformly accelerated motion is

To perform calculations of speeds and accelerations, it is necessary to switch from writing equations in vector form to writing equations in algebraic form. The vectors of initial velocity and acceleration can have different directions, so the transition from an equation in vector form to equations in algebraic form can be quite difficult. The problem of finding the module and the direction of the speed of uniformly accelerated motion at any moment of time can be successfully solved in the following way. As you know, the projection of the sum of two vectors on any coordinate axis is equal to the sum of the projections of the terms of the vectors on the same axis. Therefore, to find the projection of the velocity vector on an arbitrary axis OH you need to find the algebraic sum of the projections of the vectors and onto the same axis:

The projection of the vector onto the axis is considered positive if from the projection of the beginning to the projection of the end of the vector it is necessary to go in the direction of the axis, and negative in the opposite case.

From the last equation it follows that the graph of the dependence of the projection of the speed of uniformly accelerated motion on time is a straight line. If the projection of the initial speed on the axis OH is zero, then this line passes through the origin.

Establish a connection between the projection of the displacement vector on the coordinate axis OH with uniform rectilinear motion with the projection of the velocity vector on the same axis and time. With uniform rectilinear motion, the graph of the dependence of the projection of speed on time is a straight line parallel to the abscissa axis. Projection of body movement over time t with uniform movement at speed v defined by the expression s x = v x t. The area of ​​the rectangle lying under the straight line is directly proportional to the product or projection of the displacement.

Equation for the coordinate of a point at uniformly accelerated motion. To find the coordinate x points at any time need to the initial coordinate x 0 points add the projection of the displacement vector to the axis Oh:

x = x 0 + s x

From the expressions it follows:

x = x 0 + v 0x t + a x t 2 /2

From equations 2.5 and 2.7, an equation can be obtained that connects the projections of the final velocity of the initial velocity and acceleration with the projection of the body's displacement:

If the projection of the initial velocity is equal to zero, we obtain the expression

From this expression, you can find the projection of the speed or acceleration from the known value of the projection of displacement.

Test purpose

The technique is designed to assessknowledge , under the section "Mechanics". The material is intended forstudents first course of vocational education.

Test instructions

The test is given exactly60 minutes... Don't stay too long on one task. Perhaps you are on the wrong track and it is better to move on to the next task. But don't give up too easily; most tasks can be solved if you - show a little perseverance. The answer to the task consists of choosing the correct answer in your opinion. Sometimes there are several options to choose from. Write your answer in the indicated place. If you are not able to solve the problem, you should not write the answer at random. The test does not contain "tricky" tasks, but you always have to consider several solutions. Before proceeding with the solution, make sure that you understand correctly what is required of you. You will be wasting time if you tackle a solution without knowing what the task is.

Registration of works

You need to write down the answers to the test in a notebook for verification work in the form:

1 a

2 a, b

MECHANICAL ASSIGNMENTS

a) moving

b) trajectory

c) the line of motion

a) coordinate system

b) reference body

c) hours

d) moving a point

a) moving

b) travel time

c) the path traveled

b) he has a small stature.

5. The clock system performs:

a) rotary motion

b) translational motion

c) straight traffic

a) 11 m / s

b) 9 m / s

c) 1 m / s

a) displacement.

b) instantaneous speed

c) body coordinates

d) acceleration

a) constant in the direction

b) constant modulo

a) -2 m / s

b) 2 m / s

c) 50 m / s

a) kinematics

b) dynamics

c) statics

a) inertia

b) inertia

c) uniformly accelerated motion

but ) Newton's first law

b) Newton's second law

c) Newton's third law

a) internal structure

b) features of the external environment

a) fly

b) man

c) trolley

a) displacement

b) acceleration

c) application of force

a) 0.5 m / s2

b) 200 m / s2

c) 2 m / s2

a) -20 N

b) 0 N

c) 40 N

19. The gravitational constant G is equal to:

a) 6.67x10

b) 6.67x10

c) 9.8

a) elastic force

b) gravity

c) body weight

a) overload

b) weightlessness

c) free fall

a) gravity

b) body weight

c) elastic force

a) by gravity

b) the force of elasticity

c) body weight

d) equal to gravity

a) 1 m / s

b) 2 m / s

c) 0 m / s

a) with the ground

b) with vacuum

27. The work done by the force F is positive if the angle between the vector F and S:

but)

b)

in)

a) 3 s

b) 40 s

c) 160 s

a) 50 J

b) 200J

c) 2000J

a) 10 J

b) 100 J

c) 1000 J

a) kinetic energy

b) potential energy

c) mechanical work

a) 2000 J

b) 10000 J

c) -2000 J

a) 0.5 m / s

b) 1.5 m / s

c) 2 m / s

a) 0.5 J

b) 2 J

c) 5000 J

a) 0.4 N

b) 2.5 N

c) 10 N

a) 98 kg

b) 100 kg

c) 9800 kg

but ) 0.1 m / s

b) 10 m / s

c) 90 m / s

a) 0 m

b) 2.5 m

c) 5 m

39. The equation for determining the coordinates of a material point has the form Determine the acceleration with its help.

a) -3 m / s2

b) 4 m / s2

c) 8 m / s2

a) uniform

b) uniformly accelerated

c) equally slow

The key to the test

1. The line along which the point of the body moves is called

a) moving

b) trajectory

c) the line of motion

2. What constitutes the reporting system.

a) coordinate system

b) reference body

c) hours

d) moving a point

3.What a taxi passenger pays for:

a) moving

b) travel time

c) the path traveled

4. The cyclist rides on the road. In which case it can be considered as a material point:

a) it moves 60 meters without stopping.

b) he has a small stature.

c) he travels a distance of 60 km.

5. The clock system performs:

a) rotary motion

b) translational motion

c) straight motion

6. The train travels with speed. The passenger goes against the movement of the train at a speed of 1 m / s, relative to the carriage. Determine the passenger's ground speed.

a) 11 m / s

b) 9 m / s

c) 1 m / s

7. The process of changing the body speed is characterized by:

a) displacement.

b) instantaneous speed

c) body coordinates

d) acceleration

8. Equally accelerated is the movement with acceleration:

a) constant in the direction

b) constant modulo

c) constant in direction and modulus

9. Vehicle speed in 5 seconds changes from 20m / s to 10m / s. Determine the acceleration of the vehicle.

a) -2 m / s

b) 2 m / s

c) 50 m / s

10.Using the equation x = x, you can determine:

a) movement with uniformly accelerated movement

b) coordinates of the body with uniform motion

c) body coordinates for uniformly accelerated motion

11. The section of mechanics that studies the laws of interaction of bodies is called:

a) kinematics

b) dynamics

c) statics

12. The phenomenon of maintaining the speed of body movement in the absence of external influences is called:

a) inertia

b) inertia

c) uniformly accelerated motion

13. Which of Newton's laws has the following formulation: there are such reporting systems in relation to which a moving body keeps its speed constant, if other bodies do not act on them, or their actions are compensated.

a) Newton's first law

b) Newton's second law

c) Newton's third law

14. The reason for the change in the speed of body movement is:

a) internal structure

b) features of the external environment

c) interaction with other bodies

15. Which body is more inert:

a) fly

b) man

c) trolley

a) displacement

b) acceleration

c) application of force

17. On a body weighing 10 kg. a force of 20N acts. Determine with what acceleration the body is moving.

a) 0.5 m / s2

b) 200 m / s2

c) 2 m / s2

18. The weight acts on the balance with a force of 20 N. With what force the balance acts on the weight.

a) -20H

b) 0 N

c) 40 N

19. Gravitational constantGis equal to:

a) 6.67x10

b) 6.67x10

c) 9.8

20. The force with which the body acts on a horizontal support or vertical suspension is called:

a) elastic force

b) gravity

c) body weight

21. The disappearance of weight when the support moves with the acceleration of gravity is called:

a) overload

b) weightlessness

c) free fall

22. Using this formula, you can determine:

a) gravity

b) body weight

c) elastic force

23. The force resulting from deformation and directed in the direction opposite to the movement of body particles during deformation is called:

a) by gravity

b) the force of elasticity

c) body weight

24. Choose all the correct answer options. Friction force:

a) is equal in magnitude to the external force

b) directed towards the movement of the body.

c) directed in the opposite direction of movement

d) equal to gravity

25. Two trolleys weighing 200 kg each. move towards each other at a speed of 1m / s. How fast they will move after an inelastic impact.

a) 1 m / s

b) 2 m / s

c) 0m / s

26.What does a rocket missile interact with when moving:

a) with the ground

b) with vacuum

c) with gases generated during combustion.

27. Work done by forceF, is positive if the angle between the vectorFandS:

but)

b)

in)

28. Hoisting crane with a capacity of 2 kW., Performed work 0.08 MJ. How long did the work take?

a) 3 s

b) 40from

c) 160 s

29. Determine the potential energy of a person weighing 100 kg, at a height of 2 meters

a) 50 J

b) 200J

c) 2000J

30. Determine the kinetic energy of a 2 gram bullet traveling at a speed of 100 m / s.

a) 10 J

b) 100 J

c) 1000 J

31. The formula allows you to determine:

a) kinetic energy

b) potential energy

c) mechanical work

32. The kinetic energy of the body has changed from 4000J to 6000J. Determine the work of the body:

a) 2000 J

b) 10000 J

c) -2000 J

33. A 15-ton railroad car is moving at a speed of 2 m / s, catching up with a stationary car weighing 5 tons. What will be the speed of the cars after they collide?

a) 0.5 m / s

b) 1.5m / s

c) 2 m / s

34. The sled, moving evenly under the force of 50 N, moved 100 meters. What kind of work do they do in doing so?

a) 0.5 J

b) 2 J

c) 5000 J

35. Determine the force under which a body weighing 5 kg. Acquires an acceleration of 2m / s?

a) 0.4 N

b) 2.5 N

c) 10 N

36. Determine the body weight if the force of gravity is 980 N.

a) 98 kg

b) 100Kg

c) 9800 kg

37. The car, moving evenly in 3 seconds, drove 30 meters. Determine its speed.

a) 0.1 m / s

b) 10m / s

c) 90 m / s

38. The boy threw the ball to a height of 2.5m and caught it again. Determine the movement of the ball.

a) 0 m

b) 2.5 m

c) 5 m

39. The equation for determining the coordinates of a material point has the form. Determine with its help the acceleration.

a) -3 m / s2

b) 4 m / s2

c) 8 m / s2

40. The projection of the speed of a moving body changes according to the law. Describe the nature of the movement:

a) uniform

b) uniformly accelerated

c) equally slow

Work No. 9

Development of a hypertext document

Option 1

Using the snippets below, develop a hypertext document on Newton's Second Law by defining keywords and making connections between the snippets.

Fragment 1. The property of a body, on which its acceleration depends when interacting with other bodies, is called inertia.

Fragment 2. The quantitative measure of body inertia is body weight. Body mass is a physical quantity that characterizes inertia.

Fragment 3. With an uneven translational movement, the speed of the body changes over time. The process of changing the speed of a body is characterized by acceleration.

Fragment 4. For a quantitative expression of the action of one body on another, the concept of "force" is introduced. Force is a vector quantity, that is, it is characterized by a direction. A unit of force is a force that imparts an acceleration of 1 m / s to a body weighing 1 kg.

Fragment 5. To quantitatively characterize the process of body movement, the concept of movement speed is introduced. The speed is expressed in meters per second.

Fragment 6. The connection between the force and the acceleration of a body is established by Newton's second law. The force acting on a body is equal to the product of the body's mass by the acceleration imparted by this force.

Option 2

Using the fragments below, develop a hypertext document on the topic "Musical Scale", ordering fragments from simpler concepts to more complex ones, defining keywords and establishing links between fragments:

Fragment 1. Musical sound has the following properties: pitch, strength, duration and timbre. The pitch of the sound depends on the vibration frequency of the elastic body; strength (loudness) - from the breadth of the swing; duration - on how long the elastic body is excited; timbre is a kind of coloring of sounds.

Fragment 2. All musical sounds, if arranged in height from lowest to highest, form a musical scale. Each sound of a musical scale corresponds to sounds similar in sound, but different in pitch. They are called octaves, and the group of sounds between them is called an octave.

Fragment 3. Sound is a phenomenon that occurs due to the rapid vibration of an elastic body and is perceived by the organ of hearing - the ear.

Fragment 4. The entire scale is divided into nine octaves: seven full and two incomplete. The names of the octaves in the order of their arrangement: subcontroctave, controctave, major octave, minor octave, first octave, second octave, third octave, fourth octave, fifth octave.

Fragment 5. A full octave contains twelve different pitch sounds. Of these, only seven main ones have independent names: do, re, mi, fa, sol, la, si.

Fragment 6. The shortest distance between two adjacent sounds is called a semitone. Two semitones make up a whole tone. The distance between the sounds do-re, re-mi, fa-sol, la-si is equal to a whole tone, and between the sounds mi-fa and si-do - a semitone.

Option 3

Develop a testing hypertext document on the "Battle of Poltava" topic. The screen should display questions and offer options for answers. If the answer is correct, display the corresponding fragment of the text with the message, and if it is incorrect, display the correct answer, and then return to the current question. Organize the connection between the fragments by highlighting the keywords by which the transition from fragment to fragment will be made.

Fragment 1. The armies of which countries participated in the Battle of Poltava?

1. Russia and France 2. Russia and Poland 3. Sweden and Russia

Fragment 2. In what year did the Battle of Poltava take place?

Fragment 3. Who was at the head of the Swedish army?

Fragment 4. What was the size of the Russian army?

1. 20 000 2. 32 000 3. 56 000

Fragment 5. The answer is correct.

Back to question: 1 2 3 4

Fragment 6. The armies of Russia and Sweden took part in the Battle of Poltava.

Fragment 7. The Battle of Poltava took place in 1709.

Fragment 8. King Charles XII was at the head of the Swedish army.

Fragment 9. The Russian army numbered 32,000 people.

Physics

Equally accelerated movement

The movement of any body in real conditions is never strictly uniform and straightforward. The movement in which the body makes unequal displacements at equal intervals of time is called uneven movement.

Acceleration. With an uneven translational movement, the speed of the body changes over time. The process of changing the speed of a body is characterized by acceleration. Acceleration is called a vector quantity equal to the ratio of a very small change in the velocity vector D v to a small time interval D t for which this change occurred: (2.1) If during the time interval D t the body from point A of the trajectory moved to point B and its speed changed from v 1 before v 2, then the change in speed D v during this time interval is equal to the difference of vectors v 1 and v 2:

v = v 2 -v 1 Direction of the acceleration vector but with the direction of the velocity vector D v at very small values ​​of the interval D t, for which the speed change occurs.

If the body moves rectilinearly and its velocity increases in absolute value, then the direction of the acceleration vector coincides with the direction of the velocity vector v 2; when the speed decreases in absolute value, the direction of the acceleration vector is opposite to the direction of the speed vector v 2.

When the body moves along a curved trajectory, the direction of the velocity vector changes during the movement, the acceleration vector but in this case, it can be directed at any angle to the velocity vector v 2.

The simplest type of uneven motion is uniformly accelerated motion. Equally accelerated is a movement with acceleration constant in magnitude and direction:

a = D v / D t = const.

(2.2) From formula (2.1) it follows that when expressing the speed in meters per second, and the time in seconds, the acceleration is expressed in meters per second squared.

The speed of uniformly accelerated movement. With uniformly accelerated movement with an initial speed v 0 acceleration but equally

, (2.3) where v- speed at time t... Hence, the speed of uniformly accelerated motion is

(2.4) Speed ​​and acceleration projections. To perform calculations of speeds and accelerations, it is necessary to go from writing equations in vector form to writing equations in algebraic form. To find the projection vx of the velocity vector v on an arbitrary axis OH you need to find the algebraic sum of the vector projections v 0 and a * t on the same axis:

(2.5) Speed ​​graph.

From equation (2.5) it follows that the graph of the dependence of the projection of the speed of uniformly accelerated motion on time is a straight line. If the projection of the initial speed on the OX axis is zero ( v 0x = 0), then this straight line passes through the origin (figure on the right).

Velocity projection plots v x from time t for uniformly accelerated movements occurring with the same initial speed v 0 and various acceleration but.

Moving the body with uniform movement. Projection s x body movements over time t with uniform movement at speed v defined by the expression s x = v x t. (2.6)

Moving the body with uniformly accelerated rectilinear motion.

Projection s x body movements over time t with uniformly accelerated rectilinear motion with an initial speed v 0 and acceleration but defined by the expression

. (2.7) Equation for the coordinate of a point at uniformly accelerated motion. To find the x coordinate of a point at any time t, add the projection of the displacement vector onto the OX axis to the initial x0 coordinate of the point:

(2.8) From expressions (2.8) and (2.7) it follows:

x = x 0 + v 0x t + (a x t 2) / 2 (2.9)