VLOOKUP in physics: we analyze assignments with a teacher. VLOOKUP in physics: we analyze tasks with a teacher Reshu exam vpr physics 11

In 2017, the all-Russian verification works of VLF were tested in 11 classes in physics.

VLOOKUP is the usual test work in various subjects, but carried out according to uniform tasks and assessed according to uniform criteria developed for the whole country.

To understand how you need to perform the verification work, you should first of all familiarize yourself with the demo versions of the control measuring materials (CMM) VLOOKUP for the subjects of this year.

Official site of VPR (StatGrad)- vpr.statgrad.org

Demo version of VPR grade 11 in physics 2017

Demonstration options in physics for grade 11 will help you get an idea of ​​the structure of future CMMs, the number of tasks, their form and level of complexity. In addition, the demo contains criteria for evaluating the performance of tasks with a detailed answer, which give an idea of ​​the requirements for completeness and correctness of recording the answer.

This information is useful and can be used to plan the repetition of the material before the physics test.

VLOOKUP 2017 options in physics grade 11

Option 9	answers + criteria
Option 10	answers + criteria
Option 11	answers + evaluation criteria
Option 12	answers + evaluation criteria
Option 13	download
Option 14	download
Option 19	*
Option 20	*

* Options 19, 20 can be used for home preparation, since we have not yet been able to find the answers on the Internet.

Testing work includes 18 tasks. Physics work takes 1 hour 30 minutes (90 minutes) to complete.

Fill out the answers in the text of the work according to the instructions for the tasks. If you write down an incorrect answer, cross it out and write a new one next to it.

When performing work, it is allowed to use a calculator.

When completing assignments, you can use a draft. Draft entries will not be reviewed or graded.

We advise you to complete the tasks in the order in which they are given. To save time, skip a task that cannot be completed immediately and move on to the next. If, after completing all the work, you have time left, you can return to the missed tasks.

The points you received for the completed tasks are summed up. Try to complete as many tasks as possible and score the most points.

VLOOKUP in physics for eleventh graders includes 18 tasks, of which 14 numbers belong to the basic level of complexity, and 4. The work reflects all aspects studied in the school physics course: molecular and quantum physics, mechanics and electrodynamics.

Rating system

Writing VLOOKUP in physics takes 90 minutes, that is, 2 lessons. Students are allowed to use a non-programmable calculator. The maximum score for work is 26, the transfer of points into grades is carried out at the discretion of the management of the educational organization.

Examples of tasks with a breakdown and explanations

Exercise 1

The first task is to group physical terms. The condition gives a list of six concepts - for example:

• dynamometer, protractor, lens focal length, amperage, pressure gauge, acceleration

• farad, airplane flight, newton, ampere, ice melting, electromagnetic wave

You need to divide them into two groups, give them a name and write down the concepts in the group to which they belong, in a table of the form:

Group name	List of concepts

The band name shouldn't be too complicated. Most often these are "physical quantities" or "physical phenomena", or simply an indication of a section of physics in the form of "concepts related to kinematics."

If all the columns of the table are filled in correctly, the student gets 2 points. 1 point is awarded in the following cases:

• concepts are distributed correctly, but one of the groups is named incorrectly
• the groups are named correctly, but 1-2 mistakes were made in the distribution of concepts

In other cases, the student does not receive points for the first task.

Assignment 2

Task number 2 is associated with various motion graphs, displaying, for example, the dependence of speed or acceleration on time. Example of a graph:

1. The car moves evenly from 30 to 40 seconds
2. From 30 to 40 seconds the car is at rest
3. During 50 seconds of observation, the speed of the vehicle increases all the time
4. In 50 seconds, the direction of movement of the car changed
5. At the stage of acceleration, the car moves with an acceleration of 3m / s2

You need to choose two statements that fit the schedule. If both selected statements are correct - 2 points are given, if only one is true - 1 point, if none - 0.

Assignment 3

In the third task, there is a picture that illustrates a physical process. It is necessary to supplement it by depicting the forces acting on a certain object and the possible direction of its acceleration. The drawing can be like this:

If everything that is required in the condition is shown correctly, the student receives 2 points. If the ratio of the magnitudes of the forces is not drawn as needed, or one other mistake is made - 1 point. In other cases, the student does not receive points for the third task.

Assignment 4

In this task, a small text (3-4 sentences) is given, in which three blank words are allowed. Since this assignment is aimed at testing the knowledge of graduates in the field of conservation laws in mechanics, either the words “conserves, decreases, increases” or the names of energies are most often omitted. The text does not necessarily use all of these words, as they may be repeated. The text can be as follows:

When fired from a gun, the bullet and the gun start moving in opposite directions at different speeds. In this case, the bullet impulse model is ___________. The pulse module of the gun when fired ____________. The total impulse of the gun-bullet system is ____________ and is equal to 0.

If all the gaps are filled in correctly, the answer is estimated at 1 point, if there is at least one error - 0 points.

Assignment 5

The fifth VLOOKUP assignment in physics is a small problem that is sometimes illustrated with a picture or graph. It belongs to the branch of molecular physics.

Most often, it is required to either find the change in internal energy, or determine the temperature, or - the amount of heat. Here are examples of tasks:

1. An ideal gas receives 500 J from an external source and performs work of 200 J. How much does the internal energy of the gas change?
2. 4 metal bars, heated to different temperatures, were connected to each other according to the figure. Arrows indicate the direction of heat transfer from bar to bar. At some point in time, the temperature of the bars was 140, 95, 93 and 90 degrees Celsius. Which bar has a temperature of 93 degrees Celsius?

The student gets 1 point for the correct answer, 0 for the wrong one.

Assignment 6

This issue is also built on knowledge of molecular physics. A situation is explained, often illustrated, after which 6 statements are given, from which you need to choose the correct ones. The number of correct statements is not indicated, which complicates the task somewhat. Here is an example of a task:

The silver spider grabs an air bubble on the surface of the pond and drags it to a depth to build a house. The water temperature is the same throughout the pond. Choose those statements that correctly characterize the process that occurs with air in a bubble:

1. The volume of air in the bubble decreases
2. The volume of air in the bubble increases
3. The air mass in the bubble remains unchanged
4. Air mass in the bubble decreases
5. The air pressure in the bubble rises
6. The air pressure in the bubble decreases

If the answer contains all the correct numbers, 1 point is given. If at least one number is written incorrectly (or, along with the correct options, there is also an incorrect one) - 0 points.

Assignment 7

The seventh task belongs to another section of the subject - electrostatics. It is a small task to which a drawing is given. Most often, the problem is about the readings of electrometers or about the charges of any bodies, for example, cubes, for example:

Glass cubes 1 and 2 were put together, after which a positively charged body was brought to the cube 2. Then, without removing this body, the cubes were separated. What charges will each die have?

The correct answer to the task brings the eleventh grader 1 point.

Assignment 8

In this issue, you need to solve the problem using formulas for calculating physical quantities - for example, EMF, resistance, current, electron speed. Examples of tasks:

1. The iron operates on 220V voltage. For 5 minutes of operation, its heater produced an amount of heat of 30 kJ. Calculate the electrical resistance of the heater.
2. How long does it take for a 10 ohm heater to produce 250 kJ of heat if a 10A electric current flows through it?

If the required formula is correctly written in the answer and the correct answer is received, in which the units of measurement are indicated, it is evaluated by 2 points. If the formula is written correctly, but there is an error in the calculations - 1 point; in all other situations - 0 points.

Assignment 9

The ninth issue of VLOOKUP in physics is aimed at testing students' knowledge on topics such as electromagnetic waves and induction. The tasks are not very difficult - most often you need to arrange the types of waves in the order of increasing or decreasing their frequency or wavelength.

The correct answer brings the student 1 point.

Assignment 10

This assignment is related to quantum physics. In the condition, a figure is given - most often it is a diagram of the energy levels of an atom or a fragment of the periodic table. You need to answer the question about this drawing - for example, if the drawing is like this

it will be necessary to indicate in which of the transitions the quantum with the lowest frequency will be absorbed. If a fragment of a table is given, they usually ask to determine which element is formed after the decay of an isotope.

If it is done correctly, 1 point is given.

Assignment 11

The eleventh task begins a block related to the methods of scientific knowledge in physics. It is necessary to determine the readings of various devices - beakers, barometer, ammeter, voltmeter or dynamometer. Any situation shown in the diagram is given; the size of the measurement error is also given. Examples:

It is necessary to record the readings of the depicted device, taking into account the error. The student gets 1 point for the correct answer, 0 for the wrong one.

Assignment 12

This task belongs to the same block as the previous one, however, in contrast to it, it belongs to the increased difficulty level. Its essence lies in planning research on this hypothesis. The hypothesis and the available equipment are given in the condition. It is necessary to describe the algorithm of actions during the research, as well as to draw an experimental setup. Here's an example:

You need to investigate the dependence of the electrical resistance of a conductor on its length. There is such equipment:

• constant current source;
• voltmeter;
• ammeter;
• power supply;
• connecting wires;
• key;
• rheostat.

If the experimental setup is described correctly, and the procedure for conducting the experiment is also correctly described, 2 points are given, if there is an error in the description of the course of the experiment - 1 point, in other cases - 0 points.

Assignment 13

This task begins a block of three numbers, connected with the device and operation of technical objects, as well as with physical phenomena in life. In it, it is necessary to establish a correspondence between examples from life and physical phenomena. Two examples are given - say, heating a pump while inflating a bicycle tire and the attraction of two parallel wires with co-directional electric currents. Phenomena are given 4, which is why it is very difficult to guess the answer. If the phenomena for both examples are selected correctly, the answer is estimated at 2 points, if only to one - 1 point, and if the answer is incorrect, 0 points are given for it.

After that, the paper contains text (size - about a page) about a physical device - for example, an internal combustion engine. The history of the creation of the device, the principle of its operation and the main characteristics are described. The next two tasks are associated with it.

Task 14

In the fourteenth task, it is necessary to answer one question related to the content of the text and the principle of operation of the described device - for example, “ what kind of energy conversion takes place in an internal combustion engine" or " what physical phenomenon underlies the action of the wingsuit". The text does not give a direct answer to the question. If the answer is correct, the student gets 1 point.

Task 15

In the fifteenth issue, you need to choose from the five given statements related to the topic of the text, two correct. If both elements are chosen correctly, the answer is scored 2 points, if only one - 1 point, if none - 0 points.

Further in the text of the work, one more text is given, with which the last three tasks will be associated. The text size is about the same - about a page. The topics of the text can be very different - for example, “ abnormal expansion of water "," radioactive isotopes in medicine " or " hydrosphere of the earth". The text is accompanied by illustrative material - a table or a graph.

Task 16

In this task, the student will have to highlight information that is explicitly presented in the text or in illustrative material, therefore it is one of the easiest in all the work. For example, if the text refers to the troposphere and the average air density in it is indicated, in 16 tasks they may ask the question “ what is the approximate air density in the troposphere”, That is, you just need to rewrite the value from the text. Or, if such a scheme is given -

It may be asked which three gases are most abundant in the atmosphere. The correct answer brings the student 1 point.

Task 17

This task is slightly more difficult than the previous one, but it also belongs to the basic difficulty level. In it, you need to draw conclusions based on the text and interpret the information received. For the given table, the question of this task will sound like this: The mass of which gas - nitrogen or oxygen - is greater in the Earth's atmosphere? How many times? Round your answer to tenths. The correct answer is also evaluated with one point.

Task 18

The last task of the work belongs to the increased level of complexity. For its successful implementation, you need to apply not only the information given in the text, but also your own knowledge of the subject. It asks some not very simple question on the topic of the text, sometimes it is even necessary to put forward some own suggestions - for example, "how can the Earth be protected if asteroids are approaching it." Other examples of questions:

1. Does water freeze to the bottom in the reservoirs of central Russia?
2. Is it necessary to install filters that trap soot particles during fuel combustion in thermal power plants?
3. Are there sharp temperature jumps on the oceans?

If the student gives the correct answer to the question and gives a complete argumentation, in which there are no errors, he gets 2 points. 1 point is given if the answer is correct, but the given argumentation is not enough, or vice versa - the reasoning in the argumentation is correct, but the answer is not formulated as it should be. Otherwise, no points will be awarded for this task.

Authors: Lebedeva Alevtina Sergeevna, Physics teacher, work experience 27 years. Certificate of honor of the Ministry of Education of the Moscow Region (2013), Letter of Gratitude from the Head of the Resurrection Municipal District (2015), Certificate of honor of the President of the Association of Teachers of Mathematics and Physics of the Moscow Region (2015).

Preparation for the exam and exam

Secondary general education

Line UMK N. S. Purysheva. Physics (10-11) (BU)

UMK line G. Ya. Myakisheva, M.A. Petrova. Physics (10-11) (B)

UMK line G. Ya. Myakishev. Physics (10-11) (D)

All-Russian test work includes 18 tasks. Physics work takes 1 hour 30 minutes (90 minutes) to complete. When completing assignments, it is allowed to use a calculator. The work includes groups of tasks that test skills, which are an integral part of the requirements for the level of training of graduates. When developing the content of the verification work, the need to assess the assimilation of content elements from all sections of the basic level physics course is taken into account: mechanics, molecular physics, electrodynamics, quantum physics and elements of astrophysics. The table shows the distribution of assignments by sections of the course. Some of the tasks in the work are complex and include content elements from different sections, tasks 15-18 are based on textual information, which can also relate to several sections of the physics course at once. Table 1 shows the distribution of tasks for the main substantive sections of the physics course.

Table 1. Distribution of tasks for the main substantive sections of the physics course

VPR is developed based on the need to check the requirements for the level of training of graduates. Table 2 shows the distribution of tasks by basic skills and methods of action.

Table 2. Distribution of tasks by type of skills and methods of action

Basic skills and methods of action	Number of tasks
Know / understand the meaning of physical concepts, quantities, laws. Describe and explain physical phenomena and properties of bodies
Explain the structure and principle of operation of technical objects, give examples of the practical use of physical knowledge
Distinguish hypotheses from scientific theories, draw conclusions based on experimental data, conduct experiments to study the studied phenomena and processes
To perceive and, on the basis of the knowledge gained, independently evaluate the information contained in the media, the Internet, popular science articles

Grading system for individual assignments and work as a whole

Tasks 2, 4–7, 9–11, 13–17 are considered completed if the answer written by the student matches the correct answer. The performance of each of tasks 4–7, 9–11, 14, 16 and 17 is estimated at 1 point. The performance of each of tasks 2, 13 and 15 is estimated with 2 points, if both elements of the answer are indicated correctly; 1 point if there is a mistake in indicating one of the given answer options. The performance of each of the tasks with a detailed answer 1, 3, 8, 12 and 18 is assessed taking into account the correctness and completeness of the answer. For each task with a detailed answer, instructions are provided, which indicate what each point is for - from zero to the maximum point.

Exercise 1

Read the list of concepts that you met in the physics course: Convection, Celsius, Ohm, Photoelectric effect, Light dispersion, centimeter

Divide these concepts into two groups according to your chosen criterion. Write down the name of each group and the concepts in that group in the table.

Concept group name	List of concepts

Solution

In the task, it is required to divide the concepts into two groups according to the selected criterion, write down the name of each group and the concepts included in this group in the table.

To be able to choose from the proposed phenomena only physical ones. Remember the list of physical quantities and their units of measurement.

The body moves along the axis OH... The figure shows a graph of the dependence of the projection of the speed of the body on the axis OH from time t.

Using the picture, select from the proposed list two

1. At a moment in time t 1 body was at rest.
2. t 2 < t < t 3 the body moved evenly
3. Over the interval of time t 3 < t < t 5, the body coordinate did not change.
4. At a moment in time t t 2
5. At a moment in time t 4 the body's acceleration modulus is less than at the moment of time t 1

Solution

When performing this task, it is important to correctly read the graph of the dependence of the projection of speed on time. Determine the nature of body movement in individual areas. Establish where the body rested or moved evenly. Select the area where the body's speed has changed. It is reasonable to exclude from the proposed statements those that do not fit. As a result, we dwell on the correct statements. it Statement 1: At a moment in time t 1 the body was at rest, so the projection of the velocity is 0. Statement 4: At a moment in time t 5 the coordinate of the body was greater than at the moment in time t 2 when v x= 0. The projection of the body's velocity was greater in value. Writing down the equation of the dependence of the coordinates of the body on time, we see that x(t) = v x t + x 0 , x 0 is the starting coordinate of the body.

Difficult questions of the exam in physics: Methodology for solving problems in mechanical and electromagnetic vibrations

The body floats from the bottom of a glass of water (see figure). Draw in this figure the forces acting on the body and the direction of its acceleration.

Solution

We carefully read the assignment. Pay attention to what happens to the cork in the glass. The cork pops up from the bottom of a glass of water, and with acceleration. We indicate the forces acting on the plug. This is the force of gravity t, acting from the Earth, the force of Archimedes a, acting from the side of the liquid, and the force of resistance of the liquid c. It is important to understand that the sum of the moduli of the vectors of the force of gravity and the force of resistance of the fluid is less than the modulus of the Archimedean force. This means that the resulting force is directed upward, according to Newton's second law, the acceleration vector has the same direction. The acceleration vector is directed in the direction of the Archimedes force a

Assignment 4

Read the text and insert the missing words: decreases; increases; does not change. Words in the text can be repeated.

The skater, standing on the ice, catches a bouquet that flew up to him horizontally. As a result, the speed of the bouquet is _______________, the speed of the skater is ________________, the impulse of the body system of the skater is the bouquet of ___________.

Solution

In the task, you need to remember the concept of the momentum of the body and the law of conservation of momentum. Before the interaction, the skater's momentum was zero, so he was at rest relative to the Earth. The impulse of the bouquet is maximum. After interaction, the skater and the bouquet begin to move together with the same speed. Therefore, the speed of the bouquet decreases, skater speed increases... In general, the impulse of the skater-bouquet system is does not change.

Methodological assistance to a physics teacher

The four metal bars were laid close to each other, as shown in the figure. Arrows indicate the direction of heat transfer from bar to bar. The temperature of the bars at the moment is 100 ° C, 80 ° C, 60 ° C, 40 ° C. The bar has a temperature of 60 ° C.

Solution

The change in internal energy and its transfer from one body to another occurs in the process of interaction of bodies. In our case, the change in internal energy occurs due to the collision of chaotically moving molecules of contacting bodies. Heat transfer between bars occurs from bodies with higher internal energy, to bars with less internal energy. The process continues until they reach thermal equilibrium.

Bar B has a temperature of 60 ° C.

The figure shows PV-diagram of processes in an ideal gas. The gas mass is constant. Which area corresponds to Isochoric heating.

Solution

In order to correctly select the section of the graph corresponding to isochoric heating, it is necessary to recall isoprocesses. The task is simplified by the fact that the graphs are given in axes PV... Isochoric heating, a process when the volume of an ideal gas does not change, and pressure increases with increasing temperature. Recall - this is Charles's law. Therefore, this is the site OA... We exclude the site OS, where the volume also does not change, but the pressure decreases, which corresponds to the cooling of the gas.

Metal ball 1, fixed on a long insulating handle and charged + q, bring alternately into contact with two of the same balls 2 and 3, located on insulating supports and having, respectively, charges - q and + q.

What charge will remain on the ball # 3.

Solution

After the interaction of the first ball with the second ball of the same size, the charge of these balls will become equal to zero. Since these charges are the same in modulus. After the contact of the ball of the first with the third, a redistribution of the charge will occur. The charge will be divided equally. Will be on q/ 2 on each.

Answer: q/2.

Assignment 8

Determine how much heat will be released in the heating coil in 10 minutes, with an electric current of 2 A. Resistance of the coil is 15 Ohm.

Solution

The first step is to convert the units of measurement to the SI system. Time t= 600 s, Further, we note that when the current passes I = 2 A spiral with resistance R= 15 Ohm, the amount of heat is released during 600 s Q = I 2 Rt(Joule-Lenz law). Let's substitute numerical values ​​into the formula: Q= (2 A) 2 15 Ohm 600 s = 36000 J

Answer: 36000 J.

Assignment 9

Arrange the types of electromagnetic waves emitted by the Sun in decreasing order of their wavelengths. X-ray radiation, infrared radiation, ultraviolet radiation

Solution

Familiarity with the scale of electromagnetic waves suggests that the graduate must clearly understand in what sequence the electromagnetic radiation is located. Know the relationship of wavelength to radiation frequency

where v- radiation frequency, c- the speed of propagation of electromagnetic radiation. Remember that the speed of propagation of electromagnetic waves in a vacuum is the same and equal to 300,000 km / s. The scale begins with long waves of a lower frequency, this is infrared radiation, the next radiation with a higher frequency, respectively, is ultraviolet radiation and the higher frequency of the proposed ones is X-ray radiation. Realizing that the frequency increases and the wavelength decreases, we write in the required sequence.

Answer: Infrared radiation, ultraviolet radiation, X-ray radiation.

Using the fragment of the Periodic Table of Chemical Elements, shown in the figure, determine the isotope of which element is formed as a result of the electronic beta decay of bismuth

Solution

β - decay in an atomic nucleus occurs as a result of the conversion of a neutron into a proton with the emission of an electron. As a result of this decay, the number of protons in the nucleus increases by one, and the electric charge increases by one, while the mass number of the nucleus remains unchanged. Thus, the transformation reaction of the element is as follows:

in general. For our case, we have:

Charge number 84 corresponds to polonium.

Answer: As a result of the electronic beta decay of bismuth, polonium is formed.

Improvement of the methods of teaching physics in Russia: from the 18th to the 21st centuries

Assignment 11

A) The scale division and measurement limit of the device are equal, respectively:

1. 50 A, 2A;
2. 2mA, 50mA;
3. 10 A, 50 A;
4. 50 mA, 10 mA.

B) Record the result of the electrical voltage, taking into account that the measurement error is half the division value.

1. (2.4 ± 0.1) V
2. (2.8 ± 0.1) V
3. (4.4 ± 0.2) V
4. (4.8 ± 0.2) V

Solution

The task tests the ability to record the readings of measuring instruments, taking into account a given measurement error and the ability to correctly use any measuring device (beaker, thermometer, dynamometer, voltmeter, ammeter) in everyday life. In addition, it focuses on recording the result, taking into account significant figures. We determine the name of the device. This is a milliammeter. A device for measuring current strength. The units are mA. The measuring range is the maximum scale value, 50 mA. Graduation 2 mA.

Answer: 2mA, 50mA.

If it is required to record the readings of the measuring device according to the figure, taking into account the error, then the execution algorithm is as follows:

We determine that the measuring device is a voltmeter. The voltmeter has two measuring scales. We pay attention to which pair of terminals is used by the device, and therefore we work on the upper scale. Measurement limit - 6 V; Value of division with = 0.2 V; the measurement error according to the condition of the problem is equal to half the division value. ∆ U= 0.1 V.

Readings of the measuring device, taking into account the error: (4.8 ± 0.1) V.

• Paper;
• Laser pointer;
• Protractor;

In response:

1. Describe the procedure for conducting the study.

Solution

You need to investigate how the angle of refraction of light changes depending on the substance in which the phenomenon of refraction of light is observed. The following equipment is available (see picture):

• Paper;
• Laser pointer;
• Semicircular plates made of glass, polystyrene and rock crystal;
• Protractor;

In response:

1. Describe the experimental setup.
2. Describe the procedure

The experiment uses the installation shown in the figure. The angle of incidence and angle of refraction are measured with a protractor. It is necessary to carry out two or three experiments in which the beam of a laser pointer is directed at plates made of different materials: glass, polystyrene, rock crystal. The angle of incidence of the beam on the flat face of the plate is left unchanged, and the angle of refraction is measured. The obtained values ​​of the angles of refraction are compared.

VLOOKUP in questions and answers

Assignment 13

Establish a correspondence between examples of the manifestation of physical phenomena and physical phenomena. For each example from the first column, pick the appropriate name for the physical phenomenon from the second column.

Write down the selected numbers in the table under the corresponding letters.

Answer:

Solution

Let's establish a correspondence between examples of manifestation of physical phenomena and physical phenomena. For each example from the first column, we select the corresponding names of the physical phenomenon from the second column.

Under the action of the electric field of a charged ebony stick, the needle of an uncharged electrometer deflects when the stick is brought to it. Due to the electrification of the conductor through the influence. The magnetization of a substance in a magnetic field occurs when iron filings are attracted to a piece of magnetic ore.

Answer:

Read the text and complete tasks 14 and 15

Electrostatic precipitators

At industrial enterprises, electric gas cleaning from solid impurities is widely used. The action of the electrostatic precipitator is based on the use of a corona discharge. You can do the following experiment: a vessel filled with smoke suddenly becomes transparent if sharp metal electrodes, oppositely charged from an electric machine, are introduced into it.

The figure shows a diagram of a simplest electrostatic precipitator: inside a glass tube there are two electrodes (a metal cylinder and a thin metal wire stretched along its axis). The electrodes are connected to an electrical machine. If you blow a stream of smoke or dust through the tube and start the machine, then at a certain voltage sufficient to ignite a corona discharge, the outgoing air stream becomes clean and transparent.

This is explained by the fact that when a corona discharge is ignited, the air inside the tube is highly ionized. Gas ions adhere to dust particles and thus charge them. Charged particles under the action of an electric field move to the electrodes and settle on them

Task 14

What process is observed in a gas in a strong electric field?

Solution

We carefully read the proposed text. Select the processes that are described in the condition. This is a corona discharge inside a glass tube. The air is ionizing. Gas ions adhere to dust particles and thus charge them. Charged particles under the action of an electric field move to the electrodes and settle on them.

Answer: Corona discharge, ionization.

Task 15

Choose from the list provided two correct statements. Indicate their numbers.

1. A spark discharge occurs between the two electrodes of the filter.
2. Silk thread can be used as a fine wire in the filter.
3. According to the connection of the electrodes shown in the figure, negatively charged particles will settle on the walls of the cylinder.
4. At low voltages, air cleaning in the electrostatic precipitator will be slow.
5. A corona discharge can be observed at the tip of a conductor placed in a strong electric field.

Solution

For the answer, we will use the text about electrostatic precipitators. We exclude incorrect statements from the proposed list using the description of electrical air purification. We look at the figure and pay attention to the connection of the electrodes. The filament is connected to the negative pole, the cylinder wall to the positive pole of the source. The charged particles will settle on the cylinder walls. True statement 3. Corona discharge can be observed at the tip of a conductor placed in a strong electric field.

Read the text and complete Assignments 16-18

When exploring great depths, such underwater vehicles as bathyscaphes and bathyspheres are used. The Bathysphere is a deep-sea apparatus in the shape of a ball, which is lowered into the water from the side of the ship on a steel cable.

Several prototypes of modern bathyspheres appeared in Europe in the 16th – 19th centuries. One of them is a diving bell, the design of which was proposed in 1716 by the English astronomer Edmond Halley (see figure). A wooden bell, open at the base, housed up to five people, partially submerged in water. They received air from two barrels alternately lowered from the surface, from where air entered the bell through a leather sleeve. Wearing a leather helmet, the diver could conduct observations outside the bell, receiving air from it through an additional hose. The exhaust air was discharged through a tap located at the top of the bell.

The main disadvantage of the Halley bell is that it cannot be used at great depths. As the bell sinks, the density of the air in it increases so much that it becomes impossible for them to breathe. Moreover, during a long stay of a diver in a zone of increased pressure, the blood and tissues of the body are saturated with air gases, mainly nitrogen, which can lead to the so-called decompression sickness when a diver ascends from a depth to the surface of the water.

Prevention of decompression sickness requires adherence to working hours and proper organization of decompression (exit from the high pressure zone).

The divers' stay at depth is regulated by special safety rules for diving operations (see table).

Task 16

How does the air pressure change as the bell sinks?

Task 17

How does the diver's allowable operating time change with increasing diving depth?

Task 16-17. Solution

We read the text carefully and examined the drawing of a diving bell, the design of which was proposed by the English astronomer E. Galley. We got acquainted with the table in which the time of divers' stay at depth is regulated by special safety rules for diving operations.

Pressure (in addition to atmospheric), atm.	Permissible time spent in the work area

The table shows that the greater the pressure (the greater the immersion depth), the shorter the time a diver can be on it.

Task 16. Answer: Air pressure increases

Task 17. Answer: Allowable running time decreases

Task 18

Is it permissible for a diver to work at a depth of 30 m for 2.5 hours? Explain the answer.

Solution

A diver's work at a depth of 30 meters for 2.5 hours is permissible. Since at a depth of 30 meters, the hydrostatic pressure is approximately 3 · 10 5 Pa or 3 atm of atmosphere) in addition to the atmospheric pressure. The allowable time for a diver to stay at this pressure is 2 hours 48 minutes, which is more than the required 2.5 hours.

1. Task 17 No.

solar system

2. Task 1 No.

Concept group name

List of concepts

3. Task 18 No.

4. Task 2 No.

Please selecttwo

5. Task 4 No.

1) decreases

2) increases

3) does not change

m

6. Task 5 No.

7. Task 5 No.

1) gas temperature;

3) the mass of a gas particle;

4) gas pressure;

5) momentum of a gas particle;

6) gas temperature.

8. Task 7 No.

Electrometer readings A

Electrometer B readings

9. Task 9 No.

1) B

2) C

3) D

10. Task 6 No.

11. Task 10 No.

12. Task 12 No.

- multimeter;

- ruler;

In response:

13. Task 13 No.

EXAMPLES

PHYSICAL PHENOMENA

A) lightning

A

14. Task 14 No.

15. Task 15 No.

16. Task 16 No.

Read the text and complete assignments 16-18.

Answers

1. Task 17 No.

Determine the length of a year on Mars. Express the answer in days and round up to a whole number, for a year on Earth it is not a leap year.

Read the text and complete assignments 16-18.

solar system

The central object of the solar system is the star Sun. The overwhelming part of the entire mass of the system is concentrated in the Sun (about 99.866%); it holds by its gravity the planets and other bodies belonging to the solar system and revolving around the sun. The table shows the main characteristics of the planets of the solar system.

Between the orbits of Mars and Jupiter is the main belt of asteroids - minor planets. There are many asteroids; they collide, disintegrate, change the orbits of each other, so that some of the fragments, as they move, cross the Earth's orbit.

The passage of debris (meteoric bodies) through the earth's atmosphere looks like "shooting stars" from the surface of the earth. On rare occasions when larger fragments pass, a fireball can be seen flying across the sky. This phenomenon is called a fireball.

Moving in the atmosphere, a solid body heats up due to deceleration, and an extensive luminous shell, consisting of hot gases, forms around it. From strong air resistance, a meteoric body often splits, and its fragments - meteorites with a roar fall to the Earth.

Explanation.

From the table we find that the length of a year on Mars is 1.88 of the length of a year on Earth: 1.88 · 365 days ≈ 686 days.

Answer:686 days.

2. Task 1 No.

Read the list of concepts that you encountered in your physics course:

charge, support reaction force, friction, electrometer, acceleration, electrical capacity.

Divide these concepts into two groups according to your chosen criterion. Write down the name of each group and the concepts in that group in the table.

Concept group name

List of concepts

Explanation.

Possible answer:

Concepts from dynamics - support reaction force, friction, acceleration.

Concepts from electrostatics - charge, electrometer, electrical capacity.

3. Task 18 No.

Is it possible to observe such a phenomenon as a fireball while on the moon? Explain the answer.

Explanation.

Possible answer:

1. You can't.

2. The moon has no atmosphere of its own. Cosmic bodies falling on the surface of the Moon will not heat up (and glow) during the fall due to the lack of resistance forces.

4. Task 2 No.

The car is driving in a straight street. The graph shows the dependence of its speed on time.

Please selecttwo statements that correctly describe the movement of the vehicle, and write down the numbers under which they appear.

1) For the first 3 seconds, the car stands still, and then moves at uniform acceleration.

2) The first 3 s the car moves uniformly, and then - uniformly accelerated.

3) The maximum vehicle speed for the entire observation period is 54 km / h.

4) After 10 seconds, the car stopped.

5) After 5 seconds, the car drove in the other direction.

Explanation.

1) For the first 3 seconds, the car moves uniformly, and then moves uniformly. The statement is not true.

2) The first 3 s the car moves uniformly, and then - uniformly accelerated. The statement is correct.

3) The maximum vehicle speed is observed at the moment s and is: km / h. The statement is correct.

4) After 10 seconds, the vehicle moves evenly. The statement is not true.

5) After 5 s, the car moves equally slowly, its speed module decreases linearly, and the direction of the speed vector was opposite to the direction of the acceleration vector. The statement is not true.

Answer: 23.

5. Task 4 No.

Read the text and insert the missing words. The words in the answer may be repeated.

1) decreases

2) increases

3) does not change

From the top of the inclined plane from a state of rest, a load with a mass slips without frictionm ... When descending, the kinetic energy of the load __________, the potential energy of the load __________, the total mechanical energy of the load __________.

Explanation.

With a decrease in the height of a body above the level of the Earth, its potential energy decreases. In this case, according to the law of conservation of energy, the total energy of the system remains unchanged, and the kinetic energy must increase.

Answer: 213.

6. Task 5 No.

The four metal bars (A, B, C and D) were placed side by side as shown in the figure. Arrows indicate the direction of heat transfer from bar to bar. The temperatures of the bars are currently 90 ° C, 80 ° C, 50 ° C, 30 ° C. Which of the bars has a temperature of 80 ° C?

Explanation.

Heat transfer goes from a more heated body to a less heated one. The direction of the arrows shows thatt a > t c , t a > t b , t b > t c , t b > t d , t c> t dor, combining,t a > t b > t c > t d .

This means that body B has a temperature of 80 ° C.

Answer:B.

7. Task 5 No.

An ideal gas in molecular physics is a theoretical model of a gas in which the size of gas particles can be neglected, the average kinetic energy of gas particles is many times greater than the potential energy of their interaction, collisions of gas particles with each other and with the walls of the vessel are absolutely elastic. An ideal gas can be described using macro and micro parameters. Choose from the proposed list three physical quantities that can be attributed to microparameters:

1) gas temperature;

2) the average kinetic energy of gas particles;

3) the mass of a gas particle;

4) gas pressure;

5) momentum of a gas particle;

6) gas temperature.

Write the numbers in the answer in ascending order.

Explanation.

The micro-parameters of an ideal gas include characteristics related to individual molecules. From the proposed list, the microparameters are the average kinetic energy of gas particles, the mass of gas particles and the momentum of gas particles.

Answer: 235.

8. Task 7 No.

The figure shows two identical electrometers. The ball of the electrometer A is positively charged and shows 1 unit of charge, and the ball of the electrometer B is not charged. What will be the readings of electrometers if their balls are connected with a thin ebonite stick?

Electrometer readings A

Electrometer B readings

Explanation.

When the balls are connected with a thin ebonite stick, the redistribution of charges between the balls will not occur, since ebonite is not a conductor. This means that the readings of the electrometers will remain unchanged: the electrometer A will show 1 unit, the electrometer B - 0 units.

Answer: 1;0.

9. Task 9 No.

In the transformer shown in the figure, an alternating voltage is applied to input A. Induction EMF occurs on windings B, C and D. The number of turns is equal to that shown in the figure. Arrange windings B, C and D in order of increasing induction EMF. Write down the corresponding sequence of numbers in the answer.

1) B

2) C

3) D

Explanation.

For the transformer windings, the following relationship for voltage (EMF) is true:

This can be rewritten as:

Where 1 and 2 - corresponds to the first and second winding,U - winding voltage,n - the number of turns of the corresponding winding. Let's write down the ratio of turns on different contours to contour A (according to the formula, A will always be the first contour, and all the others - the second):

The greater the ratio of turns, the greater the induction EMF arising in the circuit.

Then, according to the increase in the EMF, the contours will be located in this way: C, D, B.

Answer: 231.

10. Task 6 No.

What happens to the nucleus during α decay?

1) The charge of the nucleus is increased by one

2) The charge of the nucleus is reduced by 2 units

3) The mass number is reduced by 2 units

4) The mass number increases by 2 units

Explanation.

During α-decay, the nuclear charge decreases by 2 units. The second statement is true.

Answer: 2.

11. Task 10 No.

The speed is measured using a speedometer. The error in measuring the speed using this speedometer is equal to its division value.

Record in response the speedometer reading in miles / h (mph), taking into account the measurement error, separated by a semicolon. For example, if the speedometer reading is (51 ± 3) mph, then the answer should be "51; 3".

Explanation.

It can be seen from the figure that 2 divisions fit between the marks "40" and "60", which means that the division value is 10 mph. By condition, the measurement error is equal to the division value. The needle is at 50 mph. So the speedometer reading is (50 ± 10) mph.

Answer: 50;10.

12. Task 12 No.

You need to investigate how the capacitance of the capacitor depends on the area of ​​the plates. The following equipment is available:

- multimeter;

- a set of four capacitors with different plates, but the same distance between them;

- ruler;

- constant voltage source.

Describe the procedure for conducting the research.

In response:

1. Sketch or describe the experimental setup.

2. Describe the procedure for conducting research.

Explanation.

Possible answer:

1. We measure the source voltage with a multimeter.

2. We take the first capacitor, measure the area of ​​its plates with a ruler.

3. We connect the capacitor to the source.

4. We measure the capacitance of the capacitor using a multimeter.

5. We take the next capacitor, carry out the same measurements of area and capacitance.

6. The obtained values ​​of the capacities are compared.

13. Task 13 No.

Establish a correspondence between examples and physical phenomena that these examples illustrate. For each example of the manifestation of physical phenomena from the first column, select the corresponding name of the physical phenomenon from the second column.

EXAMPLES

PHYSICAL PHENOMENA

A) lightning

B) light from a light bulb illuminates the room

1) magnetic properties of metals

2) the spread of light in the atmosphere

3) accumulation of electric charge in the atmosphere

4) transition from liquid to gaseous state

Write down the selected numbers in the table under the corresponding letters.

A

Explanation.

Lightning is a giant electrical discharge in the atmosphere. (A - 3)

Light from a bulb illuminates a room due to the properties of light to spread through the atmosphere. (B - 2)

Answer: 32.

14. Task 14 No.

What physical phenomenon is caused by the operation of an internal combustion engine?

Read the text and complete tasks 14 and 15.

Internal combustion engine

The main feature of any internal combustion engine is that the fuel is ignited directly inside its working chamber, and not in additional external carriers. During operation, chemical and thermal energy from fuel combustion is converted into mechanical work. The principle of operation of the internal combustion engine is based on the physical effect of thermal expansion of gases, which is formed during the combustion of the fuel-air mixture under pressure inside the engine cylinders.

When the engine is started, an air-fuel mixture is injected into its cylinders through the intake valves and ignited there by a spark plug. During combustion and thermal expansion of gases from overpressure, the piston sets in motion, transferring mechanical work to the rotation of the crankshaft. The operation of a piston internal combustion engine is carried out cyclically. These cycles are repeated several hundred times per minute. This ensures continuous forward rotation of the crankshaft exiting the engine.

A stroke is a working process that occurs in an engine in one stroke of the piston, more precisely, in one movement of the piston in one direction, up or down. A cycle is a collection of measures that repeat in a specific sequence. According to the number of strokes within one working cycle, the internal combustion engines are divided into two-stroke (the cycle is carried out in one crankshaft revolution and two piston strokes) and four-stroke (in two crankshaft revolutions and four piston strokes). At the same time, both in those and in other engines, the working process goes according to the following plan: intake; compression; combustion; expansion and release.

In two-stroke internal combustion engines, the work of the piston is limited to two strokes; it performs much less than in a four-stroke engine, the number of movements per certain unit of time. Friction losses are minimized. However, a lot of thermal energy is released, and two-stroke engines heat up faster and more strongly. In two-stroke engines, the piston replaces the valve timing mechanism, during its movement, at certain times, opening and closing the working intake and exhaust openings in the cylinder. The worst gas exchange in comparison with a four-stroke engine is the main disadvantage of a two-stroke ICE system. At the moment of removing the exhaust gases, a certain percentage of not only the working substance is lost, but also the power. The spheres of practical application of two-stroke internal combustion engines are mopeds and motor scooters; boat motors, lawn mowers, chainsaws, etc., low-power equipment.

Explanation.

Possible answer: expansion of gases when heated.

15. Task 15 No.

Choose two correct statements from the list provided and write down the numbers under which they are indicated.

1) The main feature of any internal combustion engine is that the fuel is ignited in additional external media.

2) The engine consists of cylinders.

3) In two-stroke internal combustion engines, the piston is limited to two strokes.

4) A measure is a collection of measures that are repeated in a certain sequence.

Explanation.

The main feature of any internal combustion engine is that the fuel is ignited directly inside its working chamber, and not in additional external carriers. The first statement is not true.

The engine consists of cylinders. The second statement is true.

In two-stroke internal combustion engines, the piston is limited to two strokes. The third statement is true.

A cycle is a collection of measures that repeat in a specific sequence. The fourth statement is not true.

Answer: 23.

16. Task 16 No.

What do the two graphs display, which confirms Andrey's conclusion?

Read the text and complete assignments 16-18.

GREENHOUSE EFFECT: REAL OR Fiction?

Living organisms need energy to live. The energy that sustains life on Earth comes from the Sun, which radiates energy into space. A tiny fraction of this energy reaches the Earth.

The Earth's atmosphere acts as a protective blanket that covers the planet's surface and protects it from the temperature extremes that would exist in an airless space.

Most of the energy emitted by the sun passes through the earth's atmosphere. The earth absorbs some of this energy and some is reflected back from the earth's surface. Some of this reflected energy is absorbed by the atmosphere.

As a result, the average temperature above the earth's surface is higher than it would be if the atmosphere did not exist. The Earth's atmosphere acts as a greenhouse, hence the term "greenhouse effect" originated.

The greenhouse effect is believed to have become more prominent during the twentieth century.

It is a fact that the average temperature of the Earth's atmosphere has increased. In newspapers and other periodicals, the increase in carbon dioxide emissions into the atmosphere is often cited as the main reason for the rise in temperatures in the twentieth century.

A schoolboy named Andrei became interested in a possible connection between the average temperature of the Earth's atmosphere and carbon dioxide emissions into the Earth's atmosphere.

In the library, he found the following two graphs.

Based on these two graphs, Andrei concluded that the increase in the average temperature of the Earth's atmosphere is indeed due to an increase in carbon dioxide emissions.