The ball rolls along the chute and the coordinates of the ball change. Solution: Let us write down the change in the coordinates of the ball along the plane over time - Solution

A boy weighing 50 kg makes a jump at an angle of 45° to the horizontal. The force of gravity acting on it at the top point of the trajectory is approximately equal to 500 N A body with a mass of 3 kg moves rectilinearly under the influence of a constant force equal in magnitude to 5 N. Determine the modulus of change in the momentum of the body in 6 s. A car is moving with the engine turned off along a horizontal section of the road at a speed of 20 m/s. How far will it travel before coming to a complete stop up the mountain slope at an angle of 30° to the horizon? Ignore friction. The ball rolls down the chute. Changing coordinates x ball over time t in the inertial reference frame is shown in the graph. Based on this graph, we can confidently say that the speed of the ball constantly increased the first 2 s the speed of the ball increased and then remained constant the first 2 s the ball moved with decreasing speed, and then was at rest an ever-increasing force acted on the ball in the interval from 0 to 4 s A constant force of 12 N acts on a body weighing 3 kg. With what acceleration does the body move? Two small balls of mass m everyone is at a distance r from each other and attract with force F. What is the force of gravitational attraction of the other two balls if the mass of one is 2 m, the mass of the other, and the distance between their centers? The balls move at the speeds shown in the figure and stick together when they collide. How will the momentum of the balls be directed after the collision? A stone of mass 1 kg is thrown vertically upward. At the initial moment, its kinetic energy is 200 J. To what maximum height will the stone rise? Neglect air resistance. A ball was dropped into water from a certain height. The figure shows a graph of changes in the coordinates of the ball over time. According to the schedule, the ball was moving with constant acceleration all the time the acceleration of the ball increased throughout the entire period of movement the first 3 s the ball moved at a constant speed after 3 s the ball moved at a constant speed The Earth attracts an icicle hanging on the roof with a force of 10 N. With what force does this icicle attract the Earth towards itself? The mass of Jupiter is 318 times the mass of the Earth, the radius of Jupiter's orbit is 5.2 times the radius of the Earth's orbit. How many times is the force of Jupiter's attraction to the Sun greater than the force of Earth's attraction to the Sun? (Consider the orbits of Jupiter and Earth as circles.) 1653 times The body moves in a straight line in one direction under the action of a constant force equal in modulus to 8 N. The momentum of the body has changed by 40 kg×m/s. How long did it take? DIV_ADBLOCK63"> A25 612 " style="width:458.95pt;border-collapse:collapse">
	The experimental conditions do not correspond to the hypothesis put forward.
	Taking into account the measurement error, the experiment confirmed the correctness of the hypothesis.
	The measurement errors are so large that they did not allow us to test the hypothesis.
	The experiment did not confirm the hypothesis.

A stone was dropped from the roof. How do the modulus of its acceleration, the potential energy in the gravitational field, and the modulus of momentum change as the stone falls? Ignore air resistance.

For each quantity, determine the corresponding nature of the change:

Write down the selected numbers for each physical quantity in the table. The numbers in the answer may be repeated.

Stone Acceleration Module	Potential energy of a stone	Pulse module

Passengers on the bus involuntarily leaned forward in the direction of travel. This is most likely due to the fact that the bus

1) turned left

2) turned right

3) started to slow down

4) began to pick up speed Answer: 3

Steel bar weighing m slides evenly and straightly along the horizontal surface of the table under the influence of a constant force F. The areas of the faces of the block are related by the relation S1:S2:S3= 1: 2: 3, and it touches the table with a face of area S 3. What is the coefficient of friction between the block and the table surface?

On the scale of a spring laboratory dynamometer, the distance between the divisions 1 N and 2 N is equal to 2.5 cm. What must be the mass of the load suspended from the spring of the dynamometer so that it stretches 5 cm?

A24

The body on which the force acts moves with acceleration. What value can be determined from these data?

A satellite moves around the Earth in a circular orbit with a radius R. Establish a correspondence between physical quantities and formulas by which they can be calculated. ( M– mass of the Earth, R – orbital radius, G– gravitational constant) .

For each position in the first column, select the corresponding position in the second and write down to the table

PHYSICAL QUANTITIES
	Satellite speed Orbital period of a satellite around the Earth

A pebble is thrown vertically upward from the surface of the earth and after some time t0 falls to the ground. Establish a correspondence between the graphs and physical quantities, the dependence of which on time these graphs can represent. For each position in the first column, select the corresponding position in the second and write down to the table selected numbers under the corresponding letters.

	PHYSICAL QUANTITIES
				Pebble velocity projection
			Pebble acceleration projection
				Kinetic energy of a pebble
		Potential energy of a pebble relative to the surface of the earth

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A boy is sledding. Compare the force of the sled on the Earth F 1 with the force of the Earth on the sled F 2.Answer:4

	F 1 < F 2
	F 1 > F 2
	F 1 >> F 2
	F 1 = F 2

The figure shows a graph of the dependence of the elastic force of a spring on the magnitude of its deformation. The stiffness of this spring is

What power does the motor of a crane lifting mechanism develop if it uniformly lifts a slab weighing 600 kg to a height of 4 m in 3 s?

Speed ​​of a body of mass m = 0.1 kg varies according to the equation υx = 0.05sin10pt, where all quantities are in SI units. Its impulse at time 0.2 s is approximately equal to Answer: 1

0.005 kg×m/s

0.16 kg×m/s

After hitting the stick, the puck began to slide up the ice slide and at its top had a speed of 5 m/s. The height of the slide is 10 m. If the friction of the puck on the ice is negligible, then after the impact the speed of the puck is equal to

A complete correct solution to each of problems C2 - C5 must include laws and formulas, the use of which is necessary and sufficient to solve the problem, as well as mathematical transformations, calculations with a numerical answer and, if necessary, a drawing explaining the solution.

The initial speed of a projectile fired vertically upward from a cannon is 200 m/s. At the point of maximum lift, the projectile exploded into two identical fragments. The fragment that flew down fell to the ground near the point of the shot at a speed 2 times greater than the initial speed of the projectile. To what maximum height did the second fragment rise? Neglect air resistance.

Answer8000m

The left figure shows the velocity vector and the resultant vector of all forces acting on the body in the inertial reference frame. Which of the four vectors in the right figure indicates the direction of the acceleration vector of this body in this frame of reference? Answer:3

A load weighing 0.1 kg is suspended from the spring of a school dynamometer. At the same time, the spring lengthened by 2.5 cm. What will be the lengthening of the spring when adding two more weights of 0.1 kg each? Answer:1

A car makes a turn on a horizontal road in a circular arc. What is the minimum radius of a car's trajectory when its speed is 18 m/s and the coefficient of friction between the tires and the road is 0.4? Answer:1

A25

The figure shows a graph of the coordinates of a bead moving along a horizontal spoke versus time. Based on the graph it can be stated that

	in section 1 the bead is at rest, and in section 2 it moves uniformly
	in section 1 the movement is uniform, and in section 2 it is uniformly accelerated
	the acceleration projection of the bead increases everywhere
	in section 2 the acceleration projection of the bead is positive

A complete correct solution to each of problems C2 - C6 must include laws and formulas, the use of which is necessary and sufficient to solve the problem, as well as mathematical transformations, calculations with a numerical answer and, if necessary, a drawing explaining the solution.

An inclined plane intersects a horizontal plane along straight line AB. The angle between the planes is a = 30°. A small washer begins to move up an inclined plane from point A with an initial speed v0 = 2 m/s at an angle b = 60° to straight line AB. During its motion, the puck slides onto line AB at point B. Neglecting friction between the puck and the inclined plane, find the distance AB.

Answer:0.4√3

A№1. A motorcyclist rides in a circle in a circus arena with a constant absolute speed. Resultant of all forces acting on the motorcyclist

1) equal to zero;

Answer:2

А№2 Strip magnet with mass m brought to a massive steel plate weighing M. Compare the force of a magnet on a plate F 1 with the force of the plate on the magnet F 2.

	F 1 = F 2
	F 1 >F 2
	F 1 < F 2

Answer:1

А№3 The figure shows conventional images of the Earth and the Moon, as well as the vector FL of the force of attraction of the Moon by the Earth. It is known that the mass of the Earth is approximately 81 times the mass of the Moon. Along which arrow (1 or 2) is the force acting on the Earth from the Moon directed and what is its magnitude?

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A№7. The figure shows a graph of changes in the modulus of the speed of rectilinear motion of a car over time in an inertial reference frame. At what time intervals is the total force acting on the car from other bodies NOT equal to zero?

1) 0 – t1; t3 – t4 2) At all times 3) t1 – t2; t2 – t3 4) In none of the specified time periods.

А№8. According to Hooke's law, the tension force of a spring when stretched is directly proportional to

1) its length in a free state;

2) its length in a tense state;

3) the difference between the length in tension and free states;

4) the sum of the lengths in tension and free states.

A№9. The law of universal gravitation allows us to calculate the force of interaction between two bodies if

1) the bodies are bodies of the Solar System;

2) the masses of the bodies are the same;

3) the masses of the bodies and the distance between their centers are known;

4) the masses of the bodies and the distance between them are known, which is much larger than the sizes of the bodies.

A№10. The reference frame is connected to the car. It can be considered inertial if the car

1) moves uniformly along a straight section of the highway;

2) accelerates along a straight section of the highway;

3) moves uniformly along a winding road;

4) rolls up the mountain by inertia.

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A№14. Which figure correctly shows the forces acting between a table and a book resting on the table?

https://pandia.ru/text/78/213/images/image047_13.gif" width="12" height="41">.jpg" width="236" height="154">

A№16. Two cubes made of the same material differ in size by 2 times. Masses of cubes

1) match;

2) differ from each other by 2 times;

3) differ from each other by 4 times;

4) differ from each other by 8 times.

A№17. A block of mass M = 300 G connected to a mass m = 200 G a weightless inextensible thread thrown over a weightless block. What is the acceleration of a block weighing 300 g? Neglect friction.

1) 2 m/s2 2) 3 m/s2 3) 4m/s2 4) 6m/s2

https://pandia.ru/text/78/213/images/image053_1.jpg" width="366" height="112 src="> А№19. Figure 5, b shows the results of experiments with a dropper installed on a moving cart (Figure 5, a). drops fall at regular intervals. In which experiment was the sum of all forces acting on the cart equal to zero?

1) In experiment 1.

2) In experiment 2.

3) In experiment 3.

4) In experiment 4.

A№20. A cart with a mass of 3 kg is pushed with a force of 6 N. The acceleration of the cart in the inertial frame is

1)18 m/s2 2) 2 m/s2 3)1.67 m/s2 4) 0.5 m/s2

A№21. A car weighing 1000 kg is traveling on a convex bridge with a radius of curvature of 40 m. What speed must the car have at the top point of the bridge for passengers at this point to feel a state of weightlessness?

1)0.05 m/cm/cm/cm/s

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А№ 23. The figure shows graphs 1 and 2 of the dependences of friction force on pressure force. The ratio μ1/ μ2 of sliding friction coefficients is equal to:

A№24. In free fall, the acceleration of all bodies is the same. This fact is explained by the fact that

1) gravity is proportional to body mass,

2) The earth has a very large mass

3) gravity is proportional to the mass of the Earth,

4) all earthly objects are very small compared to the Earth.

А№ 25 . A block of mass m moves up an inclined plane, sliding friction coefficient μ. What is the modulus of friction force?

1) μ mg; 2) μmgsinα; 3) μmg cosα; 4) mg.

A№26. A block of mass 0.1 kg rests on an inclined surface (see figure). The modulus of the friction force is equal.

SOLUTIONS to the problems of the municipal stage of the All-Russian Olympiad for schoolchildren in physics in the 2009/2010 academic year

9th grade

Up and down

A ball was allowed to roll from bottom to top on an inclined board. The ball was at a distance of 30 cm from the beginning of its path twice: 1 s and 2 s after the start of movement. Determine the initial speed and acceleration of the ball. Acceleration is considered constant.

Solution:

Let us write down the change in the coordinates of the ball along the plane over time:

Where – initial speed of the ball, – its acceleration.

It is known that at times And the ball was at a point with coordinate . Then from equation (1) we obtain the system:

(2)

The first equation of the system should be multiplied by, and the second by, and then subtract one equation from the other. As a result, we find the acceleration of the body:

(3)

Substituting the result obtained into the first equation of system (2), we find the initial velocity of the body:

(4)

Answer: ,
.

Triple balancing

Three communicating vessels, the area ratio of which is 1:2:3, contain mercury (see figure). Water is poured into the first vessel, the height of the water layer is 100 cm. Water is also added to the second vessel, but the height of the water layer is 50 cm. How much does the mercury level in the third vessel change? What layer of water should be added to the third vessel so that the level of mercury in it does not change?

Solution:

1) Equilibrium condition after pouring water into vessels 1 and 2 (see figure):

We express from here and through :

(2)

(3)

The law of conservation of the amount of mercury substance is written as:

, (4)

Where – initial mercury level.

Substituting relations (2) and (3) into equation (4), we find:

(5)

Consequently, the mercury level in the third vessel rose by

(6)

2) Let a column of water high . The equilibrium condition for liquid columns in this case will be written as:

where it is taken into account that the mercury level in the third vessel does not change
.

We express from here and through:

(8)

(9)

The law of conservation of the amount of mercury substance (4) is transformed to the form:

, (10)

Substituting relations (8) and (9) into equation (10), we find:

Answer: , .

Mysterious transfusions

There are two thermally insulated vessels. The first contains 5 liters of water, the temperature of which is t 1 = 60 0 C, the second contains 1 liter of water, the temperature of which is t 2 = 20 0 C. First, part of the water was poured from the first vessel into the second, then, when thermal equilibrium, so much water was poured from it into the first vessel so that its volumes in the vessels became equal to the original ones. After these operations, the temperature of the water in the first vessel became equal to t = 59 0 C. How much water was poured from the first vessel into the second and back?

Solution:

As a result of two transfusions, the mass of water in the first vessel remained the same, but its temperature decreased by
. Consequently, the energy of water in the first vessel decreased by the amount

,

Where – heat capacity of water, – mass of water in the first vessel.

The energy of water in the second vessel increased by . That's why

,

(– initial mass of water in the second vessel).

Hence,

The temperature of the water in the second vessel is

This is how it became after pouring some mass of water from the first vessel into the second one.
, having a temperature . Let's write the heat balance equation:

From here we find:

.

Answer:
.

Combining resistors

Two resistances are connected to a 120 V network. When they are connected in series, the current is 3A, and when connected in parallel, the total current is 16A. What is the resistance?

Solution:

Let's draw electrical circuit diagrams in two cases and write dependencies for two types of connections:

,

,

,

,

,

.

,

,

,

, (1)

,

.

(2)

Let's create a system of two equations (1) and (2):

.

Let us solve the resulting reduced quadratic equation:

,

,

,

.

.

So, resistance And can take two pairs of values: decision ... changes phases with time, and the relations themselves reveal a deep analogy with the Lorentz transformations for coordinates And time ...

T. S. Korenkova Minutes of the Central Committee meeting (2)

Methodological development

which affected ball with sides of the wall? 1) ... Solution: Let's write it down... the x and x" axes are directed along their relative speed v, and the axis... coordinates, as well as the theory of natural changes coordinates luminaries with time ... plane ecliptic and plane ...

Instructions for completing the work To complete the examination work in physics, 4 hours (240 minutes) are allotted. The work consists of 3 parts, including 36 tasks

Instructions

G A25 Ball rolls down the chute. Change coordinates ball with the flow time in inertial... solution solutions in answer form No. 2 write down ... ball With plane x = S, y = 0,  Joint solution ... with ... along inclined plane ...

Instructions for completing the work To complete the examination work in physics, 4 hours (240 minutes) are allotted. The work consists of 3 parts, including 35 tasks (11)

Instructions

In a vacuum with speed c. ... changes coordinates ball with the flow time. According to the schedule, 1) ball ... solution on the draft. Upon registration solutions in answer form No. 2 write down ... solutions The block can only move along inclined plane ...

In a straight line

\3\

\4\

\4\

\4\

\4\

\212\

\2\

\3\

\4\

When moving from left to right, movement with increasing speed corresponds to Fig. ...?

A1. Four bodies moved along an axis Oh. The table shows the dependence of their coordinates on time.

How did the other bodies move? \Where is the speed constant? =0? Changes direction?\

A1. Two material points simultaneously begin to move along the OX axis. The figure shows a graph of the velocity projection onto the OX axis as a function of time for each point. At the moment of time t = 2 s, these material points have the same

1) coordinates 2) velocity projection onto the OX axis

3) projections of acceleration onto the OX axis 4) distances traveled

\2\

\2\

\2\

A1. A material point moves in a straight line. The figure shows graphs of the dependence of the acceleration modulus of a material point on time. Which of the following graphs corresponds to uniformly accelerated motion?

1) 1 2) 2 3) 3 4) 4

A1. Bodies 1, 2 and 3 move in a straight line. What graphs of speed versus time correspond to motion with constant absolute non-zero acceleration?

1) 1 and 2 2) 2 and 3 3) 1 and 3 4) 1, 2 and 3

(+Which graphs correspond to uniform rectilinear motion with non-zero speed?)

\2\ + with initial speed, not =0?

\4\

A25. The figure shows a graph of the coordinates of a bead sliding freely along a horizontal needle versus time. Based on the graph it can be stated that

1) in section 1 the movement is uniform, and in section 2 it is equally slow

2) the projection of the acceleration of the bead in both sections is positive

3) the projection of the acceleration of the bead in section 2 is negative

4) in section 1 the bead is at rest, and in section 2 it moves uniformly

\1\
\3\

Expedited

\+ write down the equation of motion and the law of change of speed\

- 2\

3.v1.5. A skier slides along an inclined plane with uniform acceleration from a state of rest. In the second second of movement, he covered a distance of 3 m. How far did he travel in the first second of movement? \1m\

The dependence of the x coordinate of a material point on time t has the form x(t) = 25 − 10t + 5t², where all quantities are expressed in SI. The projection of the initial velocity vector of this point onto the OX axis is equal to

1) 25 m/s 2) −20 m/s 3) −10 m/s 4) 10 m/s

The dependence of the x coordinate of a material point on time t has the form x(t) = 25 − 10t + 5t², where all quantities are expressed in SI. The projection of the acceleration vector of this point onto the OX axis is equal to

1) 25 m/s² 2) −10 m/s² 3) 10 m/s² 4) 5 m/s²

A7. The figure shows a photograph of a setup for studying uniformly accelerated sliding of a carriage (1) weighing 0.1 kg along an inclined plane installed at an angle of 30° to the horizontal.

At the moment the movement begins, the upper sensor (A) turns on the stopwatch (2), and when the carriage passes the lower sensor (B), the stopwatch turns off. The numbers on the ruler indicate the length in centimeters. At what point in time does the projection of the carriage pass the number 45 on the ruler?

1) 0.80 s 2) 0.56 s 3) 0.20 s 4) 0.28 s

+ (see above) The acceleration of the carriage is equal to

1) 2.50 m/s² 2) 1.87 m/s² 3)1.25 m/s² 4) 0.50 m/s²

The figure shows a graph of speed dependence υ car from time to time t. Find the distance covered by the car in 5 s.

1) 0 m 2) 20 m 3) 30 m 4) 35 m

\1\

* The car is moving along a straight street. The graph shows the dependence of the car's speed on time.

The acceleration module is maximum in the time interval

1) from 0 s to 10 s 2) from 10 s to 20 s 3) from 20 s to 30 s 4) from 30 s to 40 s

A1. The figure shows a graph of the projection of the body's velocity versus time. The graph of the projection of body acceleration a x versus time in the time interval from 12 to 16 s coincides with the graph \4\

(+ from 5 to 10 s - ?)

The motorcyclist and cyclist simultaneously begin uniformly accelerated motion. The acceleration of a motorcyclist is 3 times greater than that of a cyclist. At the same moment in time, the speed of the motorcyclist is greater than the speed of the cyclist \3\

1) 1.5 times 2) times 3) 3 times 4) 9 times

During a running competition, during the first two seconds after the start, an athlete moved uniformly accelerated along a straight track and accelerated from a state of rest to a speed of 10 m/s. How far has the athlete traveled during this time?

1) 5 m 2) 10 m 3) 20 m 4) 40 m

The material point began to move in a straight line with zero initial speed and with constant acceleration a = 2 m/s². 3 s after the start of movement, the acceleration of this material point became zero. How far will it travel in five seconds after it starts moving?

1) 19 m 2) 20 m 3) 21 m 4) 22 m

1-59.Minsk. The speed of a body moving with constant acceleration a decreased by 2 times. Find the time during which this change in speed occurred if the initial speed of the body is .

1) /a 2) 2 /a 3) /(4a) 4) /(2a) 5) 4 /a \4\

1-33.Minsk. The dependence of the body coordinates on time has the form: x = 10 + 2t² + 5t. The average speed of the body during the first 5 s of movement is

1) 10 m 2) 15 m 3) 20 m 4) 25 m 5) 30 m \2\

1-42.Minsk. A body that begins to move uniformly accelerated from a state of rest covers the path S in the first second. How far will it travel in the first two seconds?

1) 2S 2) 3S 3) 4S 4) 6S 5) 8S \3\

1-43.Minsk. In the first three seconds?

1) 3S 2) 4S 3) 5S 4) 9S 5) 8S \4\

1-52.Minsk. With what acceleration does the body move if in the 6th second of its movement it covers a distance of 11 m? The initial speed is zero.

1) 1 m/s² 2) 3 m/s² 3) 2.5 m/s² 4) 2 m/s² 5) 4 m/s² \4\

1-51.Minsk. A body, moving uniformly accelerated from a state of rest, covered a distance of 450 m in 6 s. How long did it take the body to travel the last 150 m of the path?

1) 2.2 s 2) 3.3 s 3) 1.1 s 4) 1.4 s 5) 2.0 s \3\

Olympics-09. A body falls freely from a height of 100 m. How long will it take it to cover the last meter of the path?

8. A body, moving uniformly accelerated, covered a distance of 45 m within the fifth second from the start of movement. How far will it travel in 8 seconds from the start of movement? \\320m

\4\

Vertical

\133\

\2\

\3\

Stone thrown vertically up and reaches the highest point of the trajectory at time tA. Which of the following graphs correctly shows the dependence of the projection of the speed of the stone on the OY axis, directed vertically upward, from the moment of the throw to the time tA?

2.33.P. A body is thrown vertically upward from the Earth's surface at a speed of 10 m/s. Which of the graphs corresponds to the dependence of the projection of the body velocity on the OY axis, directed vertically upward? \3\

\2\

A body is thrown vertically upward with an initial speed V0. At the top point of the trajectory, the acceleration of this body

4) can be directed both up and down - depending on the module V0

The body falls freely vertically downwards. During the fall time, the acceleration of this body

1) increases in absolute value all the time

2) decreases in absolute value all the time

3) constant in modulus and directed downwards

4) constant in modulus and directed upwards

A body is thrown vertically upward with an initial speed of 20 m/s. What is the body's flight time to the point of maximum elevation? Neglect air resistance. 2 s 0.2 s 1.4 s 5 s

The body fell from a certain height with zero initial speed and when it hit the ground it had a speed of 40 m/s. What is the time it takes for the body to fall? Neglect air resistance. 1)0.25 s 2) 4 s 3) 40 s 4)400s

\4\

\4\

\3\

\212\

\25\

\Minsk 1-30\ What is the average speed of a body freely falling from a height H to the Earth?

1) 2) 3) 4) gH 5) g²H \4\

1-71.Minsk. A body is thrown vertically upward at a speed of 50 m/s. The displacement of the body in 8 s is equal to: 1) 60 m 2) 65 m 3) 70 m 4) 75 m 5) 80 m \5\

1-74.Minsk. A ball is thrown vertically upward from a balcony with an initial speed of 5 m/s. After 2 s the ball fell to the ground. The height of the balcony is: 1) 5 m 2) 15 m 3) 2 m 4) 8 m 5) 10 m \5\

Horizontally

A4\5\. A coin lying on the table was clicked so that it, having acquired speed, flew off the table. After time t, the modulus of the coin's velocity will be equal to

1) gt 2) 3) gt + 4) \4\

1-79.Minsk. A body is thrown horizontally at a speed of 39.2 m/s from a certain height. After 3 s, its speed will be equal to: 1) 49 m/s 2) 59 m/s 3) 45 m/s 4) 53 m/s 5) 40 m/s \1\

1-80.Minsk. A stone is thrown in a horizontal direction. After 3 s, its speed turned out to be directed at an angle of 45º to the horizon. The initial speed of the stone is:

1) 20 m/s 2) 30 m/s 3) 35 m/s 4) 25 m/s 5) 40 m/s \2\

1-87.Minsk. A stone is thrown horizontally with an initial speed of 8 m/s. How long after the throw will the velocity module become equal to 10 m/s?

1) 2 s 2) 0.6 s 3) 1 s 4) 0.4 s 5) 1.2 s \2\

1-83.Minsk. A body is thrown horizontally with speed from a height h. The body's flight range is equal.

Part 1

When completing tasks in Part 1, in answer form No. 1, under the number of the task you are performing ( A1–A25) place the “×” sign in the box whose number corresponds to the number of the answer you chose.

A1. A material point moves uniformly with speed υ circumferential radius r. If the speed of a point is twice as large, then the modulus of its centripetal acceleration is:

1) will not change; 2) will decrease by 2 times;

3) will increase by 2 times; 4) will increase 4 times.

A2. In Fig. A the directions of the velocity vectors are presented υ and acceleration a ball in an inertial frame of reference. Which of the ones shown in Fig. b directions has the vector of the resultant of all forces F , attached to the ball?

1) 1; 2) 1; 3) 3; 4) 4.

A3. The graph shows the dependence of gravity on body mass for a certain planet. The acceleration of free fall on this planet is equal to:

1) 0.07 m/s 2 ;

2) 1.25 m/s 2 ;

3) 9.8 m/s 2 ;

A4. Ratio of truck weight to passenger car weight m 1 /m 2 = 3, the ratio of the magnitudes of their impulses p 1 /p 2 = 3. What is the ratio of their speeds υ 1 /υ 2 ?

1) 1; 2) 2; 3) 3; 4) 5.

A5. The cart moves at a speed of 3 m/s. Its kinetic energy is 27 J. What is the mass of the cart?

1) 6 kg; 2) 9 kg; 3) 18 kg; 4) 81 kg.

A6. The balance beam, to which two bodies are suspended on threads (see figure), is in equilibrium. How to change the mass of the first body so that after increasing the shoulder d 1 in 3 times the equilibrium was maintained? (The rocker and threads are considered weightless.)

1) Increase 3 times; 2) increase 6 times;

3) reduce by 3 times; 4) reduce by 6 times.

A7. A constant horizontal force is applied to a system of a 1 kg cube and two springs F (see picture). There is no friction between the cube and the support. The system is at rest. First spring stiffness k 1 = 300 N/m. Second spring stiffness k 2 = 600 N/m. The elongation of the first spring is 2 cm. Force modulus F equal to:

1) 6 N; 2) 9 N; 3) 12 N; 4) 18 N.

A8. Smoke is soot particles suspended in the air. Solid soot particles do not fall down for a long time because

1) soot particles undergo Brownian motion in the air;

2) the temperature of soot particles is always higher than the air temperature;

3) the air pushes them upward according to Archimedes’ law;

4) The earth does not attract such small particles.

A9. The figure shows graphs of the pressure of 1 mole of an ideal gas versus absolute temperature for various processes. The following graph corresponds to an isochoric process:

A10. During which process does the internal energy of 1 mole of an ideal gas remain unchanged?

1) Under isobaric compression;

2) under isochoric compression;

3) with adiabatic expansion;

4) with isothermal expansion.

A11. To heat 96 g of molybdenum by 1 K, you need to transfer to it an amount of heat equal to 24 J. What is the specific heat of this substance?

1) 250 J/(kg ∙ K); 2) 24 J/(kg ∙ K);

3) 4∙10 –3 J/(kg ∙ K); 4) 0.92 kJ/(kg ∙ K).

A12. The heater temperature of an ideal Carnot heat engine is 227 °C, and the refrigerator temperature is 27 °C. The working fluid of the engine performs work equal to 10 kJ per cycle. How much heat does the working fluid receive from the heater in one cycle?

1) 2.5 J; 2) 11.35 J;

3) 11.35 kJ; 4) 25 kJ.

A13. The figure shows the location of two stationary point electric charges - q and + q. The direction of the electric field strength vector of these charges at the point A arrow corresponds to:

1) 1; 2) 2; 3) 3; 4) 4.

A14. The figure shows a section of a DC circuit. What is the resistance of this section if r= 1 Ohm?

1) 7 Ohm; 2) 2.5 Ohm; 3) 2 Ohm; 4) 3 Ohm.

A15. The figure shows a coil of wire through which electric current flows in the direction indicated by the arrow. The coil is located in a vertical plane. Dot A is on a horizontal line passing through the center of the coil. What is the direction of the magnetic field induction vector of the current at a point? A?

1) Vertically up;

2) vertically down ↓;

3) horizontally to the right →;

4) vertically to the left ←.

A16. The set of radio components for the manufacture of a simple oscillating circuit contains two inductance coils L 1 = 1 µH and L 2 = 2 µH, as well as two capacitors C 1 = 3 pF and C 2 = 4 pF. At what choice of two elements from this set is the period of natural oscillations of the circuit T will be the largest?

1) L 1 and C 1 ; 2) L 2 and C 2 ; 3) L 1 and C 2 ; 4) L 2 and C 1 .

A17. The figure shows a diagram of an experiment on the refraction of light in a glass plate. The refractive index of glass is equal to the ratio:

A18. The addition in space of coherent waves, in which a time-constant spatial distribution of the amplitudes of the resulting oscillations is formed, is called:

1) interference; 2) polarization;

3) dispersion; 4) refraction.

A19. In a certain region of space limited by planes A.E. And CD, a uniform magnetic field is created. A metal square frame moves at a constant speed directed along the frame plane and perpendicular to the field induction lines. Which of the graphs correctly shows the time dependence of the induced emf in the frame if at the initial moment of time the frame begins to intersect the plane MN(see figure), and at the moment of time t 0 touches the front side of the line CD?

A20. Which statements correspond to the planetary model of the atom?

1) Nucleus - in the center of the atom, the charge of the nucleus is positive, electrons are in orbits around the nucleus;

2) nucleus - in the center of the atom, the charge of the nucleus is negative, electrons are in orbits around the nucleus;

3) electrons - in the center of the atom, the nucleus revolves around electrons, the charge of the nucleus is positive;

4) electrons - in the center of the atom, the nucleus revolves around electrons, the charge of the nucleus is negative.

A21. The half-life of francium nuclei is 4.8 minutes. It means that:

1) in 4.8 minutes the atomic number of each francium atom will decrease by half;

2) every 4.8 minutes one francium nucleus decays;

3) all initially existing francium nuclei will decay in 9.6 minutes;

4) half of the initially available francium nuclei decays in 4.8 minutes.

A22. The thorium isotope nucleus undergoes three successive α decays. The result will be a kernel:

A23. The table shows the values ​​of the maximum kinetic energy Emax photoelectrons when the photocathode is irradiated with monochromatic light of wavelength λ:

What is the work function A of photoelectrons from the surface of the photocathode?

1) 0,5E 0 ; 2) E 0 ; 3) 2E 0 ; 4) 3E 0 .

A24. The ball rolls down the chute. The change in the coordinate of the ball over time in the inertial reference system is shown in the graph. Based on this graph, we can confidently say that:

1) the speed of the ball constantly increased;

2) for the first 2 s the speed of the ball increased and then remained constant;

3) for the first 2 s the ball moved with decreasing speed and then was at rest;

4) an ever-increasing force acted on the ball.

A25. In which of the following cases can the results of measurements of two physical quantities be compared?

1) 1 C and 1 A∙B; 2) 3 Kl and 1 F∙V;

3) 2 A and 3 C ∙ s; 4) 3 A and 2 V ∙ s.

Part 2

In tasks B1–B2 you need to indicate the sequence of numbers corresponding to the correct answer. For each position in the first column, select the desired position in the second and write down the selected numbers in the table under the corresponding letters. The resulting sequence should first be written down in the text of the examination paper, and then transferred to answer form No. 1 without spaces or other characters. (The numbers in the answer may be repeated.)

IN 1. In the school laboratory they study the oscillations of a spring pendulum at different values ​​of the pendulum mass. If we increase the mass of the pendulum, how will three quantities change: the period of its oscillations, their frequency, and the period of change of its potential energy? For each value, determine the corresponding nature of the change: 1) will increase; 2) will decrease; 3) will not change.

Write down the selected numbers for each physical quantity in the table. The numbers in the answer may be repeated.

AT 2. Establish a correspondence between the type of nuclear reaction and the nuclear reaction equation to which it belongs. For each position in the first column, select the desired position in the second and write down the selected numbers in the table under the corresponding letters.

The answer to each task in this part will be a certain number. This number must be written down in answer form No. 1 to the right of the task number ( B3–B5), starting from the first cell. Write each character (number, comma, minus sign) in a separate box in accordance with the samples given in the form. There is no need to write units of physical quantities.

AT 3. A load attached to a spring with a stiffness of 200 N/m performs harmonic vibrations with an amplitude of 1 cm (see figure). What is the maximum kinetic energy of the load?

AT 4. An isobaric process occurs with an ideal gas, in which to increase the volume of the gas by 150 dm 3 its temperature is doubled. The mass of the gas is constant. What was the original volume of gas? Express your answer in cubic decimeters (dm 3).

AT 5. A rectangular circuit formed by two rails and two jumpers is in a uniform magnetic field perpendicular to the plane of the circuit. The right jumper slides along the rails, maintaining reliable contact with them. Known quantities: magnetic field induction IN= 0.1 T, distance between rails l= 10 cm, speed of jumper movement υ = 2 m/s, loop resistance R= 2 Ohm. What is the strength of the induced current in the circuit? Express your answer in milliamperes (mA).

Do not forget to transfer all answers to answer form No. 1

A1		A2		A3		A4		A5
A6		A7		A8		A9		A10
A11		A12		A13		A14		A15
A16		A17		A18		A19		A20
A21		A22		A23		A24		A25

A task with a short answer is considered completed correctly if in the tasks B1, B2 the sequence of numbers is correctly indicated in the tasks B3, B4, B5 - number. For complete correct answers to assignments B1, B2 2 points are given, 1 point – one mistake was made; for an incorrect answer or lack thereof – 0 points. For the correct answer to tasks B3, B4, B5 1 point is given, for an incorrect answer or lack thereof 0 points.

Answers part IN: IN 1 (121); AT 2 (24); AT 3 (0,01); AT 4 (150); AT 5 (10).

*Contributors M.Yu. Demidova, V.A. Gribov etc. The 2009 examination version has been modified in accordance with the requirements of 2010. For instructions on how to complete the work and reference data that may be needed, see No. 3/2009. – Ed.

1. A ball was dropped into water from a certain height. The figure shows a graph of changes in the coordinates of the ball over time. According to the graph 4 8 X, cm t,c) the ball moved with constant acceleration all the time 2) the acceleration of the ball increased during the entire time of movement 3) for the first 3 s the ball moved at a constant speed 4) after 3 s the ball moved with a constant speed 2. The capacitor is connected to a current source in series with a 10 k Ohm resistor (see figure). The results of voltage measurements between the capacitor plates are presented in the table. Voltage measurement accuracy Δ U = 0.1 V. Estimate the current in the circuit at 3 s. Neglect the resistance of the wires and the internal resistance of the current source. 1) 220 µA 2) 80 µA 3) 30 µA 4) 10 µA + – t, s U, V 0 3.8 5.2 5.7 5.9 6.0 ε, r R C

3. The ball rolls down the chute. The change in the coordinate of the ball over time in the inertial reference system is shown in the graph. Based on this graph, we can confidently state that 1) the speed of the ball was constantly increasing 2) for the first 2 s the speed of the ball increased and then remained constant 3) for the first 2 s the ball moved with a decreasing speed and then was at rest 4) an ever-increasing force acted on the ball 2 4 X, m t, s The dependence of the voltage on the capacitor plates on the charge of this capacitor was studied. The measurement results are presented in the table. The measurement errors for the values ​​of q and U were equal to 0.005 m C and 0.01 V, respectively. The capacitance of the capacitor is approximately 1) 200 μF 2) 800 pF 3) 100 nF 4) 3 nF q, m C 0 0.01 0.02 0, 03 0.04 0.05 U, V00,040,120,160,220,24

5. The dependence of the voltage on the capacitor plates on the charge of this capacitor was studied. The measurement results are presented in the table. The measurement errors for the values ​​of q and U were equal to 0.5 μC and 0.5 V, respectively. The capacitance of the capacitor is approximately equal to 1) 200 μF 2) 800 nF 3) 100 pF 4) 3 nF q, μC U, V0 1.1 2 ,3 3.5 5.3 6.4 6. The dependence of the voltage on the capacitor plates on the charge of this capacitor was studied. The measurement results are presented in the table. The measurement errors for the values ​​of q and U were equal to 0.5 μC and 0.2 V, respectively. The capacitance of the capacitor is approximately 1) 200 μF 2) 800 nF 3) 100 pF 4) 3 nF q, μC U, V0 0.4 0 .6 0.8 1.4 1.8

7. The dependence of the voltage on the capacitor plates on the charge of this capacitor was studied. The measurement results are presented in the table. The measurement errors for the values ​​of q and U were equal to 0.5 μC and 1 V, respectively. The capacitance of the capacitor is approximately equal to 1) 200 μF 2) 800 nF 3) 100 pF 4) 3 nF q, μC U, V The dependence of the elongation of the spring on the mass was studied loads suspended from it. The measurement results are presented in the table. The measurement errors for the values ​​m were equal to 0.01 kg and 0.01 m, respectively. The spring stiffness is approximately equal to 1) 20 N/m 2) 30 N/m 3) 50 N/m 4) 100 N/m m, kg 0 0 ,10,20,30,40,5 x, m 0 0.02 0.04 0.07 0.08

9. The period of small vertical oscillations of a load of mass m suspended on a rubber band is equal to T 0. The dependence of the elastic force of the rubber band F on the elongation x is shown on the graph. The period T of small vertical oscillations of a load with a mass of 4m on this harness satisfies the relation 1) T > 2 T 0 2) T = 2 T 0 3) T = T 0 4) T 2 T 0 2) T = 2 T 0 3) T = T 0 4) T

11. The capacitor is connected to a current source in series with a 10 k Ohm resistor (see figure). The results of voltage measurements between the capacitor plates are presented in the table. Voltage measurement accuracy Δ U = 0.1 V. Estimate the current in the circuit at 2 s. Neglect the resistance of the wires and the internal resistance of the current source. 1) 220 µA 2) 80 µA 3) 30 µA 4) 10 µA + – t, c U, V 0 3.8 5.2 5.7 5.9 6.0 ε, r R C 12. The figure shows a graph dependence of the coordinates of a bead freely sliding along a horizontal needle on time. Based on the graph, it can be stated that 1) in section 1 the bead moves uniformly, and in section 2 the bead is at rest 2) in section 1 the bead moves uniformly accelerated, and in section 2 uniformly 3) in section 1 the projection of the acceleration of the bead is negative 4) the projection of the acceleration of the bead in area 2 less than in area 1 X, cm t,s 1 2

13. When studying the dependence of the period of oscillation of a spring pendulum on the mass of the load, the number of oscillations of the pendulum in 60 s was determined. The data obtained is shown in the table below. Based on these data, we can conclude that 1) the period of oscillation is proportional to the mass of the load 2) the period of oscillation is inversely proportional to the mass of the load 3) the period of oscillation is proportional to the square root of the mass of the load 4) the period of oscillation decreases with increasing mass of the load Number of oscillations in 60 s Weight of the load , kg 0.1 0.4 0.9 14. The table shows the results of measurements of the path traveled by the body over certain periods of time. These data are not contradicted by the statement that the movement of the body was uniform and the time intervals were 1) from 2 to 5.6 s 2) only from 2 to 4.4 s 3) only from 2 to 3 s 4) only from 3.6 to 5 .6 s t, s 2 2.4 3 3.6 4.4 5 5.6 S, m 0.5 0.6 0.75 0.9 1.1 1.5

15. In which of the cases below can we compare the results of measurements of two physical quantities? 1) 1 W and 1 N m/s 2) 3 W and 1 J s 3) 2 J and 3 N s 4) 3 J and 2 N/m 16. A plastic ball fell from a certain height into a deep vessel with water. The results of measuring the depth h of immersion of the ball in water at successive moments of time are given in the table. Based on these data, it can be stated that 1) the ball smoothly sinks to the bottom during the entire observation time, 2) the ball’s speed increases for the first three seconds and then decreases, 3) the ball’s speed constantly decreases throughout the entire observation time, 4) the ball sinks no less than by 18 cm, and then t, c h, cm floats up. In which of the cases below can we compare the results of measurements of two physical quantities? 1) 1 C and 1 A. B 2) 3 C and 1 F. B 3) 2 A and 1 C. s 4) 3 A and 2 V. s

18. The figure shows a graph of the coordinates of a bead sliding freely along a horizontal needle versus time. Based on the graph, it can be stated that X, cm t,s 1 2 1) in section 1 the bead moves uniformly, and in section 2 the bead is at rest 2) in section 1 the bead moves uniformly accelerated, and in section 2 the bead is at rest 3) in section 1 the acceleration projection of the bead is negative 4) the acceleration projection of the bead in section 2 is less than in section The dependence of the voltage on a section of the circuit on the resistance of this section was studied. The measurement results are presented in the table. The measurement errors for U and R values ​​were 0.4 V and 0.5 Ohm, respectively. The current strength in the circuit section is approximately equal to 1) 2 A 2) 2.5 A 3) 4 A 4) 5 A R, Ohm U, B0 3.8 8.2 11.6 16.4 19

2 1 X, m t, s 1) in section 1 the velocity module decreases, and in section 2 it increases 2) in section 1 the velocity module increases, and in section 2 it decreases 3) in section 2 the projection of acceleration ah of the bead is positive 4) in section 1 velocity module decreases, and in section 2 remains unchanged 20. The bead slides along a stationary horizontal spoke. The graph shows the dependence of the bead's coordinates on time. The Ox axis is parallel to the spoke. Based on the graph, it can be stated that 21. The dependence of the voltage on a section of the circuit on the resistance of this section was studied. The measurement results are presented in the table. The measurement errors for U and R values ​​were 0.2 V and 0.5 Ohm, respectively. The current strength in the circuit section is approximately equal to 1) 2 A 2) 2.5 A 3) 4 A 4) 5 A R, Ohm U, B

23. The dependence of the voltage on a section of the circuit on the resistance of this section was studied. The measurement results are presented in the table. The measurement errors for U and R values ​​were 0.2 V and 0.5 Ohm, respectively. The current strength in the circuit section is approximately equal to 1) 2 A 2) 2.5 A 3) 4 A 4) 5 A R, Ohm U, B0 1.8 4.2 5.8 8.4 11.6 22. The dependence was studied elongation of the spring due to the mass of the loads suspended from it. The measurement results are presented in the table. The measurement errors for the values ​​m were equal to 0.01 kg and 1 cm, respectively. The spring stiffness is approximately equal to 1) 20 N/m 2) 30 N/m 3) 50 N/m 4) 100 N/m m, kg 0 0.10 ,20,30,40,5 x, cm

24. The dependence of the elongation of a spring on the mass of loads suspended from it was studied. The measurement results are presented in the table. The measurement errors for the values ​​m were equal to 0.01 kg and 1 cm, respectively. The spring stiffness is approximately equal to 1) 20 N/m 2) 30 N/m 3) 50 N/m 4) 100 N/m m, kg 0 0.10 ,20,30,40,5 x, cm The figure shows a graph of the coordinates of a bead sliding freely along a horizontal needle versus time. Based on the graph, it can be stated that X, cm t,s 1 2 1) in section 1 the movement is uniform, and in section 2 it is uniformly accelerated 2) the projection of the acceleration of the bead increases everywhere 3) in section 2 the projection of the acceleration of the bead is positive 4) in section 1 the bead is at rest, and in section 2 it moves uniformly

27. The capacitor is connected to a current source through a resistor with a resistance of 5 k Ohms. The results of voltage measurements between the capacitor plates are presented in the table. The current through the capacitor at t = 6c is approximately equal to 1) 0 A 2) 0.8 mA 3) 1.2 mA 4) 2.4 mA t, s U, V 0 3.8 5.2 5.7 5, 9 6.0 26. The capacitor is connected to a current source through a resistor with a resistance of 5 k Ohms. The results of voltage measurements between the capacitor plates are presented in the table. The data presented in the table are consistent with the statement that 1) in the time interval from 0 to 5 s, the current through the resistor decreases monotonically over time 2) in the time interval from 0 to 5 s, the current through the resistor increases monotonically over time 3) by in the time interval from 0 to 5 s, the current through the resistor is zero 4) the current through the resistor first decreases, then increases U, V 0 3.8 5.2 5.7 5.9 6.0 t, s

28. A force F begins to be applied to a stationary body, causing acceleration a. The table shows the relationship between these quantities. Does friction force act on a body? If so, what is its maximum value? 1) 0 N 2) 1 N 3) 2 N 4) 3 N F, H a, m/s A student experiments with an incandescent lamp for a flashlight - he applies different voltages to it and measures the strength of the direct electric current flowing through the lamp. The results of his measurements are given in the table. What conclusion can a student draw from his observations? 1) the resistance of the light bulb filament increases with increasing voltage; 2) the resistance of the light bulb filament decreases with increasing voltage; 3) the resistance of the light bulb filament does not change with increasing voltage. 4) there is no connection between the resistance of the light bulb filament and the voltage on it Voltage U, V12345 Current I, mA

30. To determine the efficiency of an inclined plane, a student uses a dynamometer to lift a block with two loads evenly along the inclined plane. The student entered the data from the experiment into a table. What is the efficiency of an inclined plane? Express your answer as a percentage. 1) 10% 2) 22% 3) 45% 4) 100% Dynamometer readings when lifting a load, H1.5 Length of the inclined plane, m 1.0 Weight of the block with two loads, kg 0.22 Height of the inclined plane, m 0. l, cm m, g The graph shows the results of measuring the length of the spring for various values ​​of the mass of the loads lying in the pan of the spring scale. Taking into account measurement errors (Δ m = 1 g, Δl = 0.2 cm), the spring stiffness k is approximately equal to 1) 7 N/m 2) 10 N/m 3) 20 N/m 4) 30 N/m + – + –

32. The figure shows the results of measuring the pressure of a constant mass of rarefied gas as its temperature increases. Temperature measurement error ΔТ = 10 K, pressure Δр = Pa. The gas occupies a vessel with a volume of 5 liters. What is the number of moles of gas? 1) 0.2 2) 0.4 3) 1.0 4) 2.0 + – + – 4 ​​2 r, 10 5 Pa T, K l, cm m, g The graph shows the results of measuring the length of the spring at various values masses of loads lying in the pan of spring scales. Taking into account measurement errors (Δ m = 1 g, Δl = 0.2 cm), find the approximate length of the spring with an empty scale pan 1) 1 cm 2) 2 cm 3) 2.5 cm 4) 3 cm + – + –

34. When studying the phenomenon of the photoelectric effect, the dependence of the maximum kinetic energy E fe of photoelectrons escaping from the surface of an illuminated plate on the frequency of the incident light was investigated. The errors in measuring the frequency of light and the energy of photoelectrons were 1 x Hz and 4 x J, respectively. The measurement results, taking into account their errors, are presented in Figure E, J ν, Hz According to these measurements, Planck’s constant is approximately equal to 1) 2 x J x s 2) 5 x J x s 3) 7 x J x s 4) 9 x J x s 35. A schoolboy studied the process of direct current flowing through a wire of constant cross-section 2 mm. Changing the length of the wire L, he measured its resistance R using a milliohmmeter. The results of his measurements are given in the table. Using the table, determine the resistivity of the metal from which the wire was made. 1) 0.02 Ohm. mm 2 /m 2) 0.03 Ohm. mm 2 /m 3) 0.4 Ohm. mm 2 /m 4) 1.1 Ohm. mm 2 /m L, cm R, m Ohm

36. In the circuit shown in the figure, key K is closed at time t = 0 s. The ammeter readings at successive times are given in the table. Determine the source emf if the resistor resistance is R = 100 Ohm. Neglect the resistance of the wires and ammeter, the active resistance of the inductor and the internal resistance of the source. 1) 1.5 B 2) 3 B 3) 6 B 4) 7 B t, ms I, mA ε, r R K A 37. The figure shows the results of measuring the pressure of a constant mass of a rarefied gas as its temperature increases. Temperature measurement error ΔТ = 10 K, pressure Δр = Pa. The number of moles of gas is 0.4 mol. What volume does the gas occupy? 1) 12 l 2) 8.3 m 3 3) 85 m 3 4) 5 l + – + – 4 ​​2 r, 10 5 Pa T, K

38. A rheostat, ammeter and voltmeter are connected to the current source (Figure 1). When changing the position of the rheostat slider, as a result of observing the instruments, the dependencies shown in Figures 2 and 3 were obtained (R is the resistance of the part of the rheostat connected to the circuit). Select the correct statement(s), if any. A. The internal resistance of the current source is 2 ohms. B. The emf of the current source is 15 mV. 1) only A 2) only B 3) both A and B 4) neither A nor B ε, r A V 15 U, mB R, Ohm 30 I, mA R, Ohm fig. 1 pic. 3 fig The student studied the process of direct current flowing through a metal wire. He took pieces of wire of the same length of 50 cm, but with different cross sections. He measured the resistance of the wires using a milliohmmeter. The results of his measurements are given in the table. Using the table, determine the resistivity of the metal from which the wire was made. 1) 0.02 Ohm. mm 2 /m 2) 0.03 Ohm. mm 2 /m 3) 0.4 Ohm. mm 2 /m 4) 1.1 Ohm. mm 2 /m S, mm 2 11,522,533,5 R, m Ohm

40. A rheostat, ammeter and voltmeter are connected to the current source (Figure 1). When changing the position of the rheostat slider, as a result of observing the instruments, the dependencies shown in Figures 2 and 3 were obtained (R is the resistance of the part of the rheostat connected to the circuit). Select the correct statement(s), if any. A. The internal resistance of the current source is 2 ohms. B. The emf of the current source is 30 mV. 1) only A 2) only B 3) both A and B 4) neither A nor B ε, r A V 30 U, mB R, Ohm 15 I, mA R, Ohm fig. 3 Fig Using a heater of known power, the dependence of the temperature of 1 kg of a substance on the amount of heat received from the heater was studied. The measurement results are indicated in the figure by dots. What is the approximate specific heat capacity of this substance? 1) 6.0 kJ/(kg.K) 2) 1.0kJ/(kg.K) 3) 4.5kJ/(kg.K) 4) 2.5kJ/(kg.K) K) 8 2 t, 0 C Q, k J fig. 1

T, 0CT, 0C t, c Silver weighing 100 g with an initial temperature of 0°C is heated in a crucible in an electric furnace with a power of 50 W. The figure shows an experimentally obtained graph of the temperature T of silver versus time t. Assuming that all the heat coming from the electric furnace is used to heat the silver, determine its specific heat capacity. 1) 1000 J/(kg °C) 2) 250 J/(kg °C) 3) 2 J/(kg °C) 4) 0.25 J/(kg °C 43. The graph shows the results of measuring the length of the spring l for different values ​​of mass m of loads suspended from the spring. Error in measuring mass and length (Δ m = 0.01 kg, Δl = 1 cm) The elasticity coefficient of the spring is approximately 1) 20 N/m 2) 30 N/m 3) 50 N/m 4) 100 N/m + – + – k l, cm m, g.2 0.40.6

44. Tin weighing 200 g with an initial temperature of 0°C is heated in a crucible in an electric furnace with a power of 23 W. The figure shows an experimentally obtained graph of the temperature T of silver versus time t. Assuming that all the heat coming from the electric furnace is used to heat the silver, determine its specific heat capacity. 1) 230 J/(kg °C) 2) 57.5 J/(kg °C) 3) 2 J/(kg °C) 4) 0.23 J/(kg °C T, 0CT, 0C t, c A block weighing 500 g is dragged along a horizontal surface, applying a horizontally directed force to it. The graph shows the dependence of the dry friction force acting on the block on the distance traveled. What is the coefficient of friction of the block on the surface? 1) 0.4 2) 4 x ) 4 4) 0.2 8 2 | A tr |, J S, m

S, m t, c During the experiment, the dependence of the path S traveled by the body on time t was studied. The graph of the obtained dependence is shown in the figure. These data do not contradict the statement that A) The speed of the body is 6 m/s. B) The acceleration of the body is 2 m/s 2 1) neither A nor B 2) both A and B 3) only A 4) only B 47. When studying the current-voltage characteristic of an incandescent lamp coil, a deviation from Ohm’s law is observed for the section chains. This is due to the fact that 1) the number of electrons moving in the spiral changes 2) a photoelectric effect is observed 3) the resistance of the spiral changes when heated 4) a magnetic field arises

S, m t, c During the experiment, the dependence of the path S traveled by the body on time t was studied. The graph of the obtained dependence is shown in the figure. These data do not contradict the statement that A) The speed of the body is 6 m/s. B) The acceleration of the body is 2 m/s 2 1) neither A nor B 2) both A and B 3) only A 4) only B The block is dragged along a horizontal surface, applying a horizontally directed force to it. The coefficient of friction between the block and the surface is 0.5. The graph shows the dependence of the dry friction force acting on the block on the distance traveled. What is the mass of the block? 1) 1 kg 2) 2 kg 3) 4 kg 4) 0.4 kg 8 2 | A tr |, J S, m

Literature and Internet resources: 1. The most complete edition of standard versions of Unified State Examination tasks: 2010: Physics / author - A.V. Berkov, V.A. Gribov. – M.: AST: Astrel, The most complete edition of standard versions of Unified State Examination tasks: 2011: Physics / author-comp. A.V. Berkov, V.A. Gribov. - M.: AST: Astrel, The most complete edition of standard versions of Unified State Examination tasks: 2012: Physics / author - A.V. Berkov, V.A. Gribov. - M.: AST: Astrel, The most complete edition of standard versions of Unified State Examination tasks: 2013: Physics / author - A.V. Berkov, V.A. Gribov. – M.: AST: Astrel, Internet – portal “I will solve the Unified State Exam of the Russian Federation” – physics

 

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