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Lesson Objectives:
educational goals:
- organize the activities of students in the perception and comprehension of new material;
- improve the skills of experimental and independent activities;
development goals:
- create conditions for the development of logical thinking of students, communication skills, the ability to observe, express hypotheses, formulate conclusions;
- development of speech skills;
- development cognitive interest students to the subject.
educational goals:
- create conditions to ensure a positive emotional nature of the learning process;
- create an atmosphere of collective cooperation, mutual assistance;
- ensure the active work of everyone, achieving a sense of joint search, sharing the success of a common achievement.
Type of lesson: learning new material.
Methods: research, problem-search.
Activities:
- conversation;
- practical work;
- report on the results obtained.
Means of education.
Equipment for conducting frontal experiments:
- bars;
- dynamometers;
- cargo sets;
- tribometers;
- magnifiers;
- pieces of sandpaper;
- glasses
Handout.
Equipment for practical work in groups:
Group 1: dynamometer, wooden block, board with different surface treatment.
Group 2: dynamometer, wooden block, three different surfaces (tribometer, sandpaper sheet, smooth paper sheet).
Group 3: dynamometer, wooden block, tribometer, set of weights.
Group 4: dynamometer, wooden block, tribometer, set of weights.
Group 5: dynamometer, wooden block, tribometer, wooden roller of the same mass.
During the classes
1. Motivation
Let's start our lesson with Russian proverbs. Think about what kind of power we will talk about today?
Proverbs: “A dry spoon tears your mouth”, “Mow the scythe while dew; dew down and we are home”, “Everything goes like clockwork”, “Squeaks like an unlubricated cart”, etc..
(After discussing proverbs, students come to the conclusion that the topic of the lesson is the force of friction).
Today we will get acquainted with another force - the force of friction.
Let's write the topic of the lesson: "Friction force".
At the lesson we will play the role of scientists, experimental physicists. The science that studies friction is called tribology. But, no scientist can conduct an experiment without a good knowledge of the theory. Therefore, let's first find out the basic information about the force of friction.
2. Explanation of new material
(Students complete reference abstract in a notebook during the study of a new topic)
What force is called friction force? How is the force of friction directed?
Experience number 1: push the bar on the table. Why did he stop?
Friction is the interaction between rubbing surfaces that prevents their relative motion.
Friction force is a quantitative characteristic of friction.
How is the force of friction directed?
Against the movement of the bar, as the speed of the body decreases.
What are the causes of friction force?
1) Take two pieces of sandpaper and try to move them relative to each other. Why is it difficult to do this? Examine the surfaces of the pieces through a magnifying glass.
Conclusion: the cause of friction is the roughness of the surfaces.
2) Press two glasses together and try to move one relative to the other. This is difficult to do. Drop 2-3 drops of water on the surface of the glass and try to repeat the experiment. Moving the glass became even more difficult.
Conclusion: the cause of friction is the attraction of molecules of interacting bodies.
Types of friction force.
1) a rolling bar from an inclined plane;
2) a block at rest on an inclined plane;
3) a children's car rolling down an inclined plane.
Conclusion: there are three types of friction force: static friction, sliding friction and rolling friction.
How to measure friction force?
To measure the friction force, it is necessary to move the bar evenly. Then the dynamometer will show the force, equal to strength friction.
3. Research activities students in groups
Now you guys are ready to explore. What does the force of friction depend on?
The class is divided into 5 groups, each group receives a task. The children formulate a hypothesis, which they test during the research process.
Group #1
Purpose: to investigate the dependence of the friction force on the quality of surface treatment.
Hypothesis:
Devices and materials: dynamometer, wooden block, board with different surface treatment.
Working process:
2) With a dynamometer, pull the bar evenly over the smooth surface of the board, measuring the friction force.
3) With a dynamometer, pull the bar evenly over the rough surface of the board, measuring the friction force.
Conclusion:
Group #2.
Purpose: to investigate the dependence of the friction force on the type of rubbing surfaces.
Hypothesis:
Instruments and materials: dynamometer, wooden block, three different surfaces (tribometer, sandpaper sheet, smooth paper sheet).
Working process:
1) Calculate the scale division value of the dynamometer.
2) Using a dynamometer, pull the bar evenly over the surface of the board (tribometer), measuring the friction force.
3) With a dynamometer, pull the bar evenly on smooth paper, measuring the friction force.
4) With a dynamometer, pull the bar evenly over the sandpaper, measuring the friction force.
5) Enter the measurement results in the table.
Group #3.
Purpose: to investigate the dependence of the friction force on the pressure force.
Hypothesis:
Working process:
1) Calculate the scale division value of the dynamometer.
2) Using a dynamometer, measure the weight of the bar.
3) Put a bar on the tribometer ruler, and a weight on it and measure the sliding friction force of the bar along the ruler.
4) Put a second weight on the bar and again measure the sliding friction force of the bar along the ruler.
5) Record the measurement results in the table.
Group #4
Purpose: to investigate the dependence of the friction force on the area of rubbing surfaces.
Hypothesis:
Devices and materials: dynamometer, wooden block, tribometer, set of weights.
Working process:
1) Calculate the scale division value of the dynamometer.
3) Place the block on the other face and repeat the measurement of the friction force.
4) Enter the measurement results in the table.
Group #5
Purpose: to compare the force of sliding friction and the force of rolling friction.
Hypothesis:
Instruments and materials: dynamometer, wooden block, tribometer, wooden roller of the same mass.
Working process:
1) Calculate the scale division value of the dynamometer.
2) With a dynamometer, pull the bar evenly along the ruler of the tribometer, measuring the friction force.
3) Replace the block with a roller of the same mass and repeat the experiment.
4) Enter the measurement results in the table.
Students complete tasks on their own. They need to put forward a hypothesis, conduct an experiment, fill out forms in a notebook, analyze the results and draw a conclusion. During the experiment, the students distribute the duties themselves, with the protection of the representative of the group.
4. Discussion of the results of research activities of students
A representative from each group speaks about the topic of the study, the hypothesis put forward, the purpose of the experiment and the conclusions drawn. After each presentation, either an animation or a video clip on the research topic is viewed. The rest of the guys listen to the speeches of their comrades and fill out the table:
After filling in the table, it is self-checked. The table summarizes the work done in the lesson.
Based on this table, we can suggest ways to increase and decrease friction.
5. Organization homework: §30-31, prepare a report on friction in nature and technology.
6. Teacher: Take the knowledge control sheets and complete the tasks proposed in the test.
1. What is the force holding a nail driven into a board?
C. rolling friction force
T. sliding friction force
O. static friction force
2. During icy conditions, roads are sometimes sprinkled with sand. At the same time, the force of friction of the soles of the shoes on the ice ....
T. increases
B. does not change
E. decreases
3. A car with a trailer must move a heavy machine. Where is it more profitable to load it: in a body or a trailer?
L. in the body, in order to increase the pressure on the rear drive wheels
B. into the trailer, in order to increase the pressure on the trailer wheels
E. or in the body or in the trailer, it does not matter where.
4. How is the friction force directed when the body moves?
K. on the move
I. against the movement
D. has no direction
5. When lubricating rubbing surfaces, the friction force ...
U. does not change
H. decreases
G. increases
6. If the bus moves uniformly along a horizontal section of the track, is the traction force equal to the static friction force in this case?
K. the traction force is less than the static friction force
L. traction force is greater than the static friction force
N. the traction force is equal to the static friction force
7. When is the best time for skates to glide: on an ordinary winter day or in a big frost?
A. on a normal day, as the ice under the blades of the skates melts faster
L. in a big frost, as the ice under the blades of the skates melts faster
N. Skate glide is the same in cold weather and on a normal day
Answer table
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| ABOUT | T | L | And | H | H | ABOUT |
Let's check the answers. Who got the code word "excellent"?
Teacher: Summing up ( grading).
Reflection: Guys, using signal cards (red, green and yellow), express your opinion about the lesson: did you like the lesson or not.
Literature
- Burov V.A., Kabanov S.F., Sviridov V.I. Frontal experimental tasks in physics. M.: Education, 1981.
- Peryshkin A.V. Physics grade 7: textbook for educational institutions, M.: Bustard, 2007.
- Braverman E.M. Evenings in physics in high school. Moscow: Education, 1969.
OPTION 1
| PHYSICAL CONCEPTS | |
| A) physical quantity | 1) gas expansion 2) internal energy 3) crystal cell 4) millimeter of mercury 5) barometer |
1) force of normal pressure N 2 = 2N 1; 2) force of normal pressure N 1 = N 2; 3) coefficient of friction µ 1 =µ 2;
4) coefficient of friction µ 1 =2µ 2 . Answer:__
3. The stone is thrown vertically upwards. At the time of the throw, its kinetic energy was 40 J. What kinetic energy will the stone have at the top of its flight path? Ignore air resistance.
1) 0 2) 20 J 3) 40 J 4) 80 J Answer: ___
4. The radius of motion of the body along the circumference was reduced by 2 times without changing its linear velocity. How has it changed centripetal acceleration body? 1) increased by 4 times; 2) decreased by 4 times; 3) decreased by 2 times; 4) has doubled. Answer:____ 
5. The force F 1 acting from the side of the liquid on one piston of the hydraulic machine is 16 times less than the force F 2 acting on the other piston. Compare the modules of work (A 1) and (A 2) of these forces performed when the pistons move? Neglect friction. 1) A 1 \u003d A 2; 2) A 1 \u003d 16A 2; 3) A 2 \u003d 16A 1; 4) A 1 \u003d 4A 2. Answer:_______. 
6. The figure shows graphs of the dependence of the projection of the speed of movement on time for two bodies moving along the Ox axis. From the statements below, choose two correct ones and write down their numbers. 1) The projections of the velocity and acceleration of the body 2 on the axis Ox are negative only at times greater than t 2 . 2) At time t 1, the acceleration modulus of bodies is the same. 3) The speed modulus of body 1 at any time is greater than body 2. 4) At time t 2 body 2 has stopped 5) The initial speed of both bodies is zero. Answer:|__|__|
7. At what distance did a wagon weighing 10 tons move from a state of rest if, at the same time, work of 2000 kJ was performed by the resultant force? The car was moving with an acceleration of 1 m/s 2 . Answer: ____m.
8. The internal energy of a body depends on A. The mass of the body. B. The position of the body relative to the surface of the Earth. B. Velocity of the body (in the absence of friction) The correct answer is 1) only A; 2) only B; 3) only B; 4) only B and C Answer: _
9. The figure shows a graph of the dependence of the temperature of a certain substance on the amount of heat received. Initially, the substance was in a solid state. Using the graph data, select two true statements from the proposed list. List their numbers. 
1) The specific heat capacity of a substance in the solid state is equal to the specific heat capacity of the substance in the liquid state. 2) The boiling point of a substance is t 1. 3) At point B, the substance is in a liquid state. 4) In the process of transition from state B to state C, the internal energy of matter increases. 5) The section of the HD graph corresponds to the process of melting the substance. Answer:|__|__|
10. How much heat is released when 500 g of water, taken at 0 ° C, turns into ice at a temperature of -10 ° C? Neglect energy losses for heating the surrounding air. Answer: ____ J.
11. Two point charges will be attracted to each other if the charges 1) are the same in sign and any in modulus;
2) identical in sign and necessarily identical in modulus; 3) different in sign, but necessarily identical in modulus;
4) are different in sign and any in modulus. Answer:___
12. The figure shows a plot diagram electrical circuit AB. Two resistors with resistance R 1 and R 2 are connected in parallel in this circuit. The voltages across the resistors are U 1 and U 2 , respectively. Which of the formulas can be used to determine the voltage U on section AB? 1) U \u003d U 1 + U 2 2) U \u003d U l -U 2 3) U \u003d U 1 \u003d U 2 4) U \u003d U 1 U 2 / (U 1 + U 2). Answer:
13. Inside the coil connected to the galvanometer is a small coil connected to a direct current source. In which of the following experiments will the galvanometer record the induction current? A. In a small coil, the electric current is turned off. B. The small coil is removed from the large one.
1) only in experiment A; 2) only in experiment B; 3) in both experiments; 4) in none of the experiments. Answer: ___
14. A beam of light falls on a flat mirror. The angle between the incident beam and the reflected one was increased by 30°. The angle between the mirror and the reflected beam 1) increased by 30°; 2) increased by 15°; 3) decreased by 30°; 4) decreased by 15 °. Answer: ___
15. The figure shows an electrical circuit consisting of a current source, a resistor and a rheostat. How to change 
When moving the slider of the rheostat to the left, do the resistance of rheostat 2 and the voltage across resistor 1 change?
For each physical quantity, determine the appropriate nature of the change. 1) increases; 2) decreases; 3) does not change. Answer:16. An electric stove connected to a DC source consumes 108 kJ of energy in 120 seconds. What is the current strength in the tile spiral if its resistance is 25 ohms? Answer: ___A.
17. Below are the equations of two nuclear reactions. Which of the following is an α-decay reaction?
A. 239 92 U → 239 93 Np + 0 -1 e. B. 7 4 Be → 3 2 He + 4 2 He 1) only A; 2) only B; 3) both A and B; 4) neither A nor B. Answer: _______
18. The table shows the results of measurements of the mass m, the change in temperature t and the amount of heat Q released during cooling of cylinders made of copper or aluminum. Based on the measurements carried out, it can be argued that
| The substance from which the cylinder is made | ||||
| Cylinder #1 | ||||
| Cylinder #2 | Aluminum | |||
| Cylinder #3 | Aluminum |
temperature differences; 2) does not depend on the substance of the cylinder; 3) increases with an increase in the mass of the cylinder; 4) depends on the substance of the cylinder. Answer:___
19.In the directory physical properties different materials are shown in the following table.
| Substance | Density in the solid state, g / cm 3 | Electrical resistivity (at 20 ° C), Ohm∙mm 2 / m |
| aluminum | ||
| Constantine (alloy) | ||
| nickeline (alloy) | ||
| nichrome (alloy) |
Using the data in the table, select two true statements from the proposed list. List their numbers.
1) With equal dimensions, an aluminum conductor will have less mass and a greater electrical resistance compared to a copper conductor. 2) Nichrome and brass conductors with the same dimensions will have the same electrical resistance. 3) Constantan and nickel conductors with the same dimensions will have different masses.
4) When replacing the nickel-plated coil of the hotplate with a nichrome coil of the same size, the electrical resistance of the coil will decrease. 5) When equal area cross-section of a constantan conductor 4 m long will have the same electrical resistance as a nickeline conductor 5 m long. Answer: |__|__|
Collider
Charged particle accelerators are used to produce high-energy charged particles. The accelerator is based on the interaction of charged particles with electric and magnetic fields. Acceleration is created electric field, capable of changing the energy of particles with an electric charge. A constant magnetic field changes the direction of movement of charged particles without changing their speed, so in accelerators it is used to control the movement of particles (the shape of the trajectory).
According to their purpose, accelerators are classified into colliders, neutron sources, sources of synchrotron radiation, installations for cancer therapy, industrial accelerators, etc. A collider is an accelerator of charged particles in colliding beams, designed to study the products of their collisions. Thanks to colliders, scientists manage to impart high kinetic energy to particles, and after their collisions, to observe the formation of other particles.
The largest ring accelerator in the world is the Large Hadron Collider (LHC), built at the research center of the European Council for Nuclear Research, on the border of Switzerland and France. Scientists from all over the world, including from Russia, took part in the creation of the LHC. The large collider is named because of its size: the main ring of the accelerator is almost 27 km long; hadron - due to the fact that it accelerates hadrons (for example, protons belong to hadrons). The collider is located in a tunnel at a depth of 50 to 175 meters. Two beams of particles can move in the opposite direction at a huge speed (the collider will accelerate the protons to a speed of 0.999999998 of the speed of light). However, in a number of places their paths will intersect, which will allow them to collide, creating thousands of new particles with each collision. The consequences of the collision of particles will become the main subject of study. Scientists hope that the LHC will make it possible to find out how the universe was born.
20. In a particle accelerator 1) both the electric and magnetic fields change the direction of motion of a charged particle; 2) the electric field changes the direction of motion of a charged particle; 3) a constant magnetic field accelerates charged particles; 4) the electric field accelerates the charged particles. Answer:_____
21. In the Large Hadron Collider: A. Protons are accelerated to speeds greater than the speed of light B. Protons acquire greater kinetic energy. Correct answer: 1) only A; 2) only B; 3) both A and B; 4) neither A nor B. Answer: _____.
22. What will be the trajectory of a charged particle flying into a magnetic field with a speed directed perpendicular to the magnetic field induction vector? Explain the answer.
23. For answers to tasks 23-26, use a separate sheet. First write down the number of the task (23, 24, etc.), and then the answer to it. Write your answers clearly and legibly.. Using a carriage (bar) with a hook, a dynamometer, two weights, a guide rail, assemble an experimental setup to measure the coefficient of sliding friction between the carriage and the surface of the rail. In the answer sheet: 1) make a drawing of the experimental setup; 2) write down the formula for calculating the coefficient of sliding friction; 3) indicate the results of measuring the weight of the carriage with weights and the sliding friction force when the carriage with weights moves along the surface of the rail; 4) Write down the value of the coefficient of sliding friction.
24. A mug of water floats in a pot of water. Will water boil in a mug if the pot is put on fire? Explain the answer.
25. In a vertical uniform magnetic field on horizontal conductive rails, a horizontal steel bar is located perpendicular to them (see Fig.). The modulus of the magnetic induction vector is 0.1 T. What is the minimum current that must be passed through the block in order to move it? The distance between the rails is 15 cm, the mass of the bar is 300 g, the coefficient of sliding friction between the bar and the rails is 0.2.
26. The efficiency of a car engine is 36%. What is mechanical power engine, if at an average speed of 100 km / h it consumes 10 kg of gasoline per 100 km?
OPTION 2
The answer to tasks 1,6,9,15,19 is a sequence of numbers. Write this sequence of numbers in the answer field in the text of the work. When completing tasks 2-5, 8, 11-14, 17, 18 and 20, 21, write down one number in the answer field, which corresponds to the number of the correct answer. Answers to tasks 7,10 and 16 write down as a number, taking into account the units indicated in the answer.
1. Match between physical groups physical concepts and an example of a concept related to the corresponding group. For each physical concept from the first column, select the appropriate example from the second column. Write in the table the selected numbers under the corresponding letters.
BUT2. The figure shows graphs of the dependence of the path and speed of the body on time. Which chart matches uniformly accelerated motion? Answer: ___ 
3. A stone of mass 1 kg is thrown vertically upwards. At the initial moment of time, its energy is 200 J. To what maximum height will the stone rise? Ignore air resistance.
1) 2 m 2) 10 m 3) 20 m 4) 200 m Answer: ___.
4. With the help of a block, a load of 20 kg was lifted by applying a force of 100 N to the free end of the rope thrown over the block. What block or combination of blocks was used? 1) movable block; 2) a combination of two fixed blocks; 3) a combination of two movable blocks; 4) fixed block. Answer:____.
5. An aluminum ball suspended from a thread is lowered into a strong solution table salt. Then the ball was transferred from the sodium chloride solution to distilled water. In this case, the tension force of the thread 1) may remain unchanged or change depending on the volume of the ball; 2) will not change; 3) increase; 4) will decrease. Answer: _____.
6. The figure shows graphs of the projection of the velocity of movement of two bodies. From the statements below, choose the correct ones and write down their numbers. 1) Body 1 is at rest, body 2 moves uniformly; 2) The projections of the speed of bodies 1 and 2 are positive during the entire time of movement; 3) The velocity modulus of the body 2 decreased during the time interval 0-t 2 and increased at times greater than t 2 ; 4) The projection of the acceleration of body 2 is positive; 5) At time t 1 bodies 1 and 2 have the same speed. Answer:|__|__| 
7. How long did it take for a car weighing 10 tons to move from rest to a distance of 200 m under the action of a constant resultant force equal to 10 4 N? Answer: ____ s.
8. The internal energy of the body does not depend on A. Body temperature. B. Body weights. B. The position of the body relative to the surface of the Earth. Correct answer: 1) only A; 2) only B; 3) only B; 4) only A and B. Answer: ____
9. The figure shows a graph of the dependence of the temperature of a certain substance on the amount of heat received. Initially, the substance was in a solid state. Using the graph data, select two true statements from the proposed list. List their numbers. 1) The specific heat capacity of a substance in a solid state is less than the specific heat capacity of a substance in a liquid state. 2) The melting point of a substance is t 1 .3) At point B, the substance is in a liquid state. 4) In the process of transition from state B to state C, the internal energy of matter does not change. 5) The section of the graph VG corresponds to the process of boiling the substance. Answer:|__|__| 
10. How much heat is released when 500 g of water, taken at 20 ° C, turns into ice at a temperature of 0 ° C? Neglect energy losses for heating the surrounding air. Answer: ____ kJ.
11. From a drop that has electric charge-2e, a drop with charge +e separated. What is the electric charge of the rest of the drop? 1) –e; 2) –3e; 3) +e; 4) +3e. Answer:____. 
12. The figure shows a diagram of an electrical circuit. There are two resistors in series in this circuit.
resistance R1 and R2. Which of the following relationships is true for such a connection of resistors?
1) U = U1 + U2; 2) R= R1∙R2/(R1+R2); 3)I = I1 + I2; 4) U = U1 = U2. Answer:____. 
13. steel needle placed between the poles of a magnet. After a while, the needle became magnetized. Which poles will correspond to points 1 and 2? eleven - north pole, 2 - southern; 2) 2 - to the north pole, 1 - to the south; 3) both 1 and 2 - to the north pole; 4) both 1 and 2 - south pole Answer: ____.
14. What is the angle of incidence of the beam on the border "water - air", if it is known that the angle of refraction is equal to the angle of incidence? 1) 90°; 2) 60°; 3) 45°; 4) 0°. Answer: ____. 
16. An electric stove with a current of 6 A consumes 1080 kJ of energy. What is the time for the current to pass through the spiral of the tile if its resistance is 25 ohms? Answer:______ s.
17. Below are the equations of two nuclear reactions. Which of the following is an α-decay reaction?
A.23992 U→ 23993Np +0-1e. B. 146С → 147N + 0-1e. 1) only A; 2) only B; 3) both A and B; 4) neither A nor B. Answer: ____.
| L, m (wire length) | ||
19. In turn, the circuit (see figure) included pieces of wire 4 m, 8 m and 12 m long. For each case, the voltage and current strength were measured (see table). What conclusion can be drawn on the basis of the conducted research? 1) the resistance of the conductor is inversely proportional to its cross-sectional area; 2) the resistance of the conductor is directly proportional to its length; 3) the resistance of the conductor depends on the strength of the current in the conductor; 4) the resistance of the conductor depends on the voltage at the ends of the conductor; 5) the current strength in the conductor is inversely proportional to its resistance. Answer: |__|__| 
Read the text and complete tasks 20-22.
Cyclotron
To produce charged particles (electrons, protons, atomic nuclei, ions) of high energies, special devices are used - charged particle accelerators. The accelerator is based on the interaction of charged particles with electric and magnetic fields. An electric field is capable of directly doing work on a particle, that is, increasing its energy. The magnetic field, while creating the Lorentz force, only deflects the particle without changing its energy, and sets the trajectory along which the particles move.
Particle accelerators can be classified according to different criteria. According to the type of accelerated particles, electron accelerators, proton accelerators, and ion accelerators are distinguished. According to the nature of the particle trajectories, linear accelerators are distinguished, in which the particle beam passes through the accelerating gaps once and the particle trajectories are close to a straight line, and cyclic accelerators, in which the beams move along closed curves (for example, circles or spirals), passing through the accelerating gaps many times.
Figure 1 shows a diagram of the operation of a cyclotron - a cyclic proton (or ion) accelerator. Particles from the ion source 1 continuously enter the vacuum chamber and are accelerated by the electric field created by the electrodes 3. The magnetic field, directed perpendicular to the plane of the pattern, causes the charged particle to deviate from rectilinear motion. 
Each time, passing through the gap between the electrodes, the charged particle receives a new portion of energy and is additionally accelerated. The trajectory of an accelerating particle in a constant magnetic field results in an unwinding spiral.
Rice. 1. Scheme of particle motion in a cyclotron; the magnetic field is perpendicular to the plane of the drawing. 1 - ion source; 2 - orbit of the accelerated particle (spiral); 3 - accelerating electrodes; 4 - output device (deflecting plates); 5 - source of the accelerating field.
The cyclotron is the first of the cyclic accelerators. It was first designed and built in 1931. So far, cyclotrons have been widely used to accelerate heavy particles to relatively low energies.
20. In a cyclotron 1) electric and magnetic fields serve to change the direction of motion of a charged particle; 2) the electric field serves to increase the energy of a charged particle, and the magnetic field serves to change the direction of its movement; 3) electric and magnetic fields increase the energy of a charged particle; 4) the electric field serves to change the direction of motion of a charged particle, and the magnetic field serves to increase its energy. Answer: ___.
21. Figure 1 in the text shows the trajectory of movement (unwinding spiral) for a positively charged ion. The magnetic field of the cyclotron is directed 1) perpendicular to the plane of the drawing to us B; 2) from right to left ← B; 3) perpendicular to the plane of the drawing from us x B; 4) from left to right → B. Answer: _______.
When completing task 22 with a detailed answer, use a separate sheet. Write down the number of the task first, and then the answer to it. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification. Write your answer clearly and legibly.
22. What is the trajectory of a charged particle flying into a magnetic field in a cyclotron? Explain the answer.
23. Using a weighted balance scale, a beaker, a glass of water, cylinder No. 2, assemble an experimental setup for measuring the density of the material from which cylinder No. 2 is made. In the answer sheet: 1) draw a drawing of an experimental setup for determining the volume of a body; 2) write down the formula for calculating the density; 3) indicate the results of measuring the mass of the cylinder and its volume; 4) Record the density value of the material of the cylinder.
Task 24 is a question that requires a written answer. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification.
24. What will happen to the Earth's atmosphere if the temperature of the atmosphere drops sharply? Explain the answer.
25. In a vertical uniform magnetic field on horizontal rails, a horizontal steel bar is located perpendicular to them (see Fig.). The modulus of the magnetic induction vector is 0.1 T. To move the bar, the current that must be passed through it is 40 A. The distance between the rails is 15 cm, the mass of the bar is 300 g. What is the coefficient of sliding friction between the bar and the rails?
26. What is the amount of gasoline used by the engine of a car that has traveled 300 km from average speed 100 km/h if the mechanical power of the engine is 46 kW? Engine efficiency is 36%.
OPTION 3
The answer to tasks 1,6,9,15,19 is a sequence of numbers. Write this sequence of numbers in the answer field in the text of the work. When completing tasks 2-5, 8, 11-14, 17, 18 and 20, 21, write down one number in the answer field, which corresponds to the number of the correct answer. Answers to tasks 7,10 and 16 write down as a number, taking into account the units indicated in the answer.
1. Establish a correspondence between the physical groups of physical concepts and an example of a concept belonging to the corresponding group. For each physical concept from the first column, select the appropriate example from the second column. Write in the table the selected numbers under the corresponding letters.
| PHYSICAL CONCEPTS | |
| A) physical quantity | 1) free vibrations; 2) hertz; 3) amplitude of oscillations; 4) resonance; 5) stopwatch. |
| B) unit of physical quantity |
|
| B) a device for measuring a physical quantity |
3. The projectile, whose momentum p was directed vertically upwards, exploded into two fragments. The momentum of one fragment p1 at the moment of explosion was directed horizontally (Fig. 1). What was the direction of momentum p2 of the second fragment (Fig. 2)? 1)1; 2) 2; 3)3; 4) 4. Answer: ___. 
4. Mathematical pendulum fluctuates between positions 1 and 3 (see figure). In position 1
1) the kinetic and potential energy of the pendulum are minimal; 2) the kinetic energy of the pendulum is zero, the potential energy is maximum; 3) the kinetic energy of the pendulum is maximum, the potential energy is minimum; 4) the kinetic and potential energy of the pendulum is maximum. Answer:____. 
5. A homogeneous body floats, partially immersed in water, if its density is 1) less density water; 2) equal to or greater than the density of water; 3) more density of water; 4) is equal to the density of water. Answer: ____.
6. The figure shows graphs of coordinates versus time for two bodies moving along the Ox axis.
Using the graph data, select two true statements from the proposed list. List their numbers.
1) At the moment of time t 1 the body (2) moved with a greater speed in absolute value. 2) At time t 2 bodies had the same absolute speed. 3) In the time interval from t1 to t2, both bodies moved in the same direction. 4) In the time interval from 0 to t1, both bodies moved uniformly. 5) By the time t1, the body (1) has traveled a longer distance. Answer: |__|__| 
7. With the help of a cable, a bucket was removed from a well 10 m deep. The weight of the bucket is 1.5 kg, and the weight of water in the bucket is 10 kg. What is the minimum work done by the elastic force of the cable? Answer:____.
8. Brownian motion of paint particles in water is 1) a consequence of attraction between atoms and molecules; 2) repulsion between atoms and molecules; 3) chaotic and continuous motion of molecules; 4) displacement of water layers due to the temperature difference between the lower and upper layers. Answer:____.
9. The figure shows a graph of the dependence of temperature on time when a certain substance is heated, which was originally in a solid state. Using the graph data, select two true statements from the proposed list. List their numbers. 1) at point B, the substance is in a liquid state; 2) the melting process corresponds to the section BC; 3) the section CD corresponds to the process of heating the liquid; 4) the specific heat capacity of a substance in a liquid state is greater than in a solid state; 5) the process to which the section DE corresponds occurs without energy absorption. Answer: |__|__| 
10. A metal candlestick weighing 2 kg is heated to a temperature of 630 °C. When the candlestick cooled to a temperature of 30 °C, heat equal to 504 kJ was released. What is the specific heat capacity of the candlestick substance? Answer: ___ J / (kg ∙ ° C).
11. The figure shows point charged bodies. Bodies A and B have the same negative charge, and body C has the same positive charge. What is the modulus and direction of the resultant force acting on the charge B from the charges A and C? 1) F = FA + FB; direction 2; 2) F = FA - FB; direction 2; 3) F = FA + FB; direction 1; 4) F = FA - FB; direction 1. Answer: ____. 
12. The figure shows a graph of the dependence of the current in the conductor on the voltage at its ends. What is the resistance of the conductor? 1) 0.25 ohm; 2) 2 ohm; 3) 4 ohm; 4) 8 ohm. Answer:____. 
13. Inside the coil connected to the galvanometer is a small coil connected to a current source. For the first second from the beginning of the experiment, the small coil is motionless inside big coil. Then, within the next second, it is removed from the large coil. For the third second, the small coil is outside the large coil. During the fourth second, the small coil is pushed into the large one. In what time interval(s) will the galvanometer detect the appearance of an induction current? 1) only 0 - 1s; 2) 1s - 2s and 3s - 4s; 3) 0 - 1s and 2s - 3s; 4) only 1s - 2s Answer: ___.
14. The object is at a distance of 2F from the converging lens. How far is the image of the object from the lens? 1) smaller F; 2) between F and 2F; 3) larger 2F; 4) equal to 2F. Answer: ___.
15. The nickel-plated coil of the electric stove was replaced with a nichrome coil of the same length and cross-sectional area. How will the electrical resistance of the spiral and the power change in this case? electric current consumed by tiles? For each value, determine the appropriate nature of the change: 1) will increase; 2) decrease; 3) will not change.
Write in the table the selected numbers for each physical quantity. Numbers in the answer may be repeated.16. What current strength does the ammeter show? Answer: ____A.
17. Which type radioactive radiation is a stream of negatively charged particles? 1) α-radiation; 2) neutron flux; 3) γ – radiation; 4) β-radiation. Answer: ____.
18. It is necessary to experimentally check whether the buoyancy force depends on the volume of the body immersed in water. Which of the indicated pairs of bodies can be used for such a check?
1) A and B; 2) C and D; 3) A and B; 4) A and D. Answer: _____.
The following table is presented in the reference book of physical properties of various materials.
| Substance | Density in the solid state *, g / cm 3 | Melting point, °С | Specific heat of fusion, kJ/kg |
| aluminum | |||
Read the text and complete tasks 20-22,
Microscope
The human eye is characterized certain resolution(limiting resolution), that is, the smallest distance between two points of the observed object, at which these points can still be distinguished from one another. For a normal eye, when moving away from the object at the distance of the best vision (D = 250 mm), the average normal resolution is 0.176 mm. The sizes of microorganisms, most plant and animal cells, small crystals, details of the microstructure of metals and alloys, etc. significantly less than this value.
An increase in the resolving power of the eye is achieved with the help of optical instruments. When observing small objects, an optical microscope is used.
An enlarged image of an object in a microscope is obtained using an optical system consisting of two short-focus converging lenses - an objective and an eyepiece (Fig. 1). The distance between the lens and the eyepiece can be changed when focusing. The subject S is placed at a distance slightly greater than the focal length of the lens. In this case, the lens will give a valid inverted magnified image S 1 of the subject. This intermediate image is viewed by the eye through the eyepiece. The eyepiece is positioned so that the intermediate image S 1 is slightly closer to its focal plane. The eyepiece acts like a magnifying glass. S 2 is the image that the human eye will see through the eyepiece.
A good microscope can magnify several hundred times. However, by carrying out large magnifications, we can increase the resolution of the microscope only up to a certain limit. This is due to the fact that it becomes necessary to take into account wave properties Sveta. The fundamental limitation lies in the impossibility of obtaining, using electromagnetic radiation, an image of an object smaller in size than the wavelength of this radiation. The limiting resolution of a microscope is related to the wavelength of electromagnetic radiation. It is possible to "penetrate deeper" into the microworld by using radiation with shorter wavelengths.
20. The fundamental limitation of the resolution of the microscope is determined by 1) the optical power of the lens; 2) the wavelength of the radiation used; 3) the intensity of the radiation used; 4) the optical power of the lens and eyepiece. Answer: __.
21. The image of an object received through an eyepiece is: 1) imaginary, reduced; 2) imaginary, enlarged; 3) real, enlarged; 4) real, reduced. Answer: _____.
When completing task 22 with a detailed answer, use a separate sheet. Write down the number of the task first, and then the answer to it. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification. Write your answer clearly and legibly.
22. Is it possible to increase the resolution of a microscope without limit? Explain the answer.
Use a separate sheet to answer questions 23-26. First write down the number of the task (23, 24, etc.), and then the answer to it. Write your answers clearly and legibly.
23. Using a tripod with a clutch and foot, a spring, a dynamometer, a ruler and a set of 3 weights, assemble an experimental setup to study the dependence of the elastic force that occurs in the spring on the degree of stretching of the spring. Determine the tension of the spring by hanging one, two and three weights in turn from it. Use a dynamometer to determine the weight of the loads. In the answer sheet: 1) make a drawing of the experimental setup; 2) indicate the results of measuring the weight of the goods and the elongation of the spring for three cases in the form of a table (or graph); 3) formulate a conclusion about the dependence of the elastic force arising in the spring on the degree of stretching of the spring.
Task 24 is a question that requires a written answer. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification.
24. Is it possible to draw liquid into a syringe while in spaceship in the state of zero-gravity? Explain the answer.
For tasks 25-26, you must write complete solution, which includes the entry short term problem (Given), writing formulas, the use of which is necessary and sufficient to solve the problem, as well as mathematical transformations and calculations leading to a numerical answer.
25. The heater is connected in series with a rheostat with a resistance of 7.5 ohms to a 220 V network. What is the resistance of the heater if the power of the electric current in the rheostat is 480 W?
26. The impact part of a hammer weighing 10 tons falls freely from a height of 2.5 m onto a steel part weighing 200 kg. By how many degrees did the part heat up if the hammer made 32 blows? Heating consumes 25% of the hammer's energy.
OPTION 4
The answer to tasks 1,6,9,15,19 is a sequence of numbers. Write this sequence of numbers in the answer field in the text of the work. When completing tasks 2-5, 8, 11-14, 17, 18 and 20, 21, write down one number in the answer field, which corresponds to the number of the correct answer. Answers to tasks 7,10 and 16 write down as a number, taking into account the units indicated in the answer.
| BUT | ||||
2. The figure shows a graph of the dependence of the module of the speed of a car moving in a straight line along the road, from time to time. In what time interval is the resultant of all forces acting on the car equal to zero? 1) from 0 to 2 s; 2) from 2 s to 4 s; 3) from 4 s to 7 s; 4) from 0 to 7 s. Answer: ___
3. The projectile, whose momentum p was directed vertically downwards, exploded into two fragments. The momentum of one fragment p 1 at the moment of explosion was directed horizontally (Fig. 1). What was the direction of momentum p2 of the second fragment (Fig. 2)? 1)1; 2) 2; 3)3; 4) 4. Answer: ___.
4. The mathematical pendulum oscillates between positions 1 and 3 (see figure). In position 2
1) the kinetic and potential energy of the pendulum is maximum; 2) the kinetic energy of the pendulum is zero, the potential energy is maximum; 3) the kinetic and potential energy of the pendulum are minimal; 4) the kinetic energy of the pendulum is maximum, the potential energy is minimum; Answer:____.
5. The ship passes from the mouth of the river to the salty sea. In this case, the Archimedean force acting on the ship,
1) increase; 2) decrease or increase depending on the size of the ship; 3) will not change; 4) decrease. Answer: ____.
6. The figure shows graphs of the dependence of the coordinate on time for a body moving along the Ox axis.
Using the graph data, select two true statements from the proposed list. List their numbers. 1) The OA section corresponds to the accelerated movement of the body. 2) Section AB corresponds to the state of rest of the body. 3) At time t 1, the body had the maximum acceleration in absolute value.
4) Time t 3 corresponds to the stop of the body. 5) At time t 2 the body had the maximum acceleration in absolute value. Answer: |__|__|
7. A concrete slab with a volume of 0.25 m3 was evenly raised to a height of 6 m using a cable. Density of concrete 2000 kg/m3. What is the work done by the elastic force of the cable? Answer:____.
8. When a copper wire is stretched between molecules 1), only attractive forces act; 2) both attractive and repulsive forces act, but the attractive forces are greater than the repulsive forces; 3) both attractive and repulsive forces act, but the repulsive forces are greater than the attractive forces; 4) only repulsive forces act. Answer: ____.
9. The figure shows a graph of the dependence of temperature on time when a certain substance is cooled, which was originally in a liquid state. Using the graph data, select two true statements from the proposed list. List their numbers. 1) at point B, the substance is in a liquid state; 2) section VG corresponds to the process of crystallization; 3) the process of liquid cooling corresponds to section AB;
4) point A corresponds to the beginning of crystallization; 5) the process to which the BV section corresponds occurs without energy absorption. Answer: |__|__|
10. A copper body weighing 2 kg, when cooled, released an amount of heat equal to 8000 J. How many degrees did its temperature drop? Answer: ____°C
11. The figure shows point charged bodies. Bodies B and C have the same negative charge, and body A has the same positive charge. What is the modulus and direction of the resultant force acting on the charge B from the charges A and C? 1) F = FA - FB; direction 1; 2) F = FA - FB; direction 2; 3) F = FA + FB; direction 2; 4) F = FA + FB; direction 1. Answer: ____.
12. The figure shows a graph of the voltage U at the ends of the resistor versus the current I flowing through it. The resistance R of the resistor is 1) 0.04 ohm; 2) 0.05 ohm; 4) 20 Ohm; 4) 24 Ohm. Answer: _____
13. Inside the coil connected to the galvanometer is a small coil connected to a current source. The axes of the coils match. For the first second from the beginning of the experiment, the small coil is motionless inside the large coil. Then, over the next second, it is rotated about the vertical axis clockwise. For the third second, the small coil again remains at rest. During the fourth second, the small coil is rotated counterclockwise. At what time intervals will the galvanometer detect the appearance of an induction current in the coil?
1) induction current can occur at any time interval; 2) inductive current will occur at time intervals of 1-2 s, 3-4 s; 3) the induction current will not occur in any period of time; 4) inductive current will occur at time intervals of 0-1 s, 2-3 s. Answer:_______.
14. The object is at a distance less than 2F and greater than F from the converging lens. At what distance is the image of the object from the lens? 1) greater than 2F; 2) between F and 2F; 3) smaller F; 4) equal to 2F. Answer: _____.
15. In the process of rubbing against silk, the glass ruler acquired a positive charge. How did the number of charged particles on the ruler and silk change in this case, provided that the exchange of atoms during friction did not occur? For each physical quantity, determine the appropriate nature of the change: 1) increased; 2) decreased; 3) has not changed.
Write in the table the selected numbers for each physical quantity. Numbers in the answer may be repeated.
16. A voltage of 12 mV is applied to an iron conductor 10 m long and with a cross-sectional area of 2 mm 2. The strength of the current flowing through the conductor is equal to Answer: ____ mA.
17. The argon nucleus 40 18 Ar contains 1) 40 protons and 22 neutrons; 2) 40 protons and 18 neutrons; 3) 18 protons and 40 neutrons; 4) 18 protons and 22 neutrons. Answer: ____.
18. The position expressed by Democritus that all bodies are composed of particles was at that time 1) a hypothesis; 2) theory; 3) scientific fact; 4) by law. Answer:___.
19. Two rods of the same size with carnations fixed to them with paraffin are heated from the end (see figure). To the left of the candle is a copper rod, and to the right is an iron rod. As the wax heats up, it melts and the cloves fall one by one. The observed process is faster for a copper rod, since
1) the density of copper is greater; 2) the thermal conductivity of copper is greater; 3) the density of iron is greater; 4) the thermal conductivity of iron is greater.
Answer:____.
Read the text and complete tasks 20-22.
Item color
The color of different objects illuminated by the same light source (for example, the sun) is very diverse. The main role in such effects is played by the phenomena of reflection and transmission of light. When considering an opaque object, we perceive its color depending on the radiation that is reflected from the surface of the object and enters our eye. When a transparent body is viewed through the light, its color will depend on the transmission of rays of different wavelengths.
The luminous flux incident on the body is partially reflected (scattered), partially transmitted and partially absorbed by the body. The share of the light flux involved in each of these processes is determined using the appropriate coefficients: reflection p, transmission m and absorption oc. So, for example, the reflection coefficient is equal to the ratio the light flux reflected by the body to the light flux incident on the body.
Each of these coefficients may depend on the wavelength (color), due to which various effects arise when illuminating bodies.
Bodies in which absorption is large for all rays, and reflection and transmission are very small, will be black opaque bodies (for example, soot). For red opaque rose petals, the reflection coefficient is close to unity for red (for other colors it is very small), the absorption coefficient, on the contrary, is close to unity for all colors except red, the transmittance is practically zero for all wavelengths. Transparent green glass has a transmittance close to unity for green, while the reflectance and absorption coefficients for green are close to zero. Transparent bodies can have different colors in transmitted and reflected light.
The difference in the values of the coefficients p, m and a and their dependence on the wavelength of light causes an extraordinary variety in the colors and shades of various bodies.
20. The absorption coefficient is equal to 1) the luminous flux absorbed by the body; 2) the ratio of the light flux incident on the body to the light flux absorbed by the body; 3) the luminous flux incident on the body; 4) the ratio of the light flux absorbed by the body to the light flux incident on the body. Answer: ____.
21. For a white opaque body 1) the transmission and absorption coefficients are close to zero for all wavelengths; 2) the transmission and reflection coefficients are close to zero for all wavelengths; 3) the transmission and absorption coefficients are close to unity for all wavelengths; 4) the transmission and reflection coefficients are close to unity for all wavelengths.
22. Chlorophyll is a green substance contained in the leaves of plants and causes their green color. What are the absorption and reflection coefficients for green leaves? Explain the answer.
When completing task 22 with a detailed answer, use a separate sheet. Write down the number of the task first, and then the answer to it. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification. Write your answer clearly and legibly.
Use a separate sheet to answer questions 23-26. First write down the number of the task (23, 24, etc.), and then the answer to it. Write your answers clearly and legibly.
23. Using a tripod with a clutch and a foot, a spring, a dynamometer, a ruler and two weights, assemble an experimental setup for measuring the stiffness of the spring. Determine the stiffness of the spring by hanging two weights from it. Use a dynamometer to measure the weight of loads. In the answer sheet: 1) make a drawing of the experimental setup; 2) write down the formula for calculating the stiffness of the spring; 3) indicate the results of measuring the weight of the weights and the elongation of the spring; 4) write down the value of the spring stiffness.
Task 24 is a question that requires a written answer. A complete answer should include not only the answer to the question, but also its detailed, logically connected justification.
24. From which bottom is it harder to lift a boat that has received a hole: from muddy or rocky? Why?
For tasks 25, 26, it is necessary to write down a complete solution, including writing a brief condition of the problem (Given), writing formulas, the use of which is necessary and sufficient to solve the problem, as well as mathematical transformations and calculations leading to a numerical answer.
25. A heater with a resistance of 20 ohms is connected in series with a rheostat with a resistance of 7.5 ohms in a 220 V network. What is the current power consumed by the heater?
26. The impact part of a hammer weighing 10 tons falls freely on a steel part weighing 200 kg. From what height does the impact part of the hammer fall if after 32 blows the part is heated by 20 °C? Heating consumes 25% of the hammer's energy.
Presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the chart?
1. normal pressure force N 2 = 2N 1
2. normal pressure force N 1 = 2N 2
2. The student performed an experiment to measure the friction force acting on two bodies moving along horizontal surfaces. Mass of the first body m 1 , mass of the second body m 2 = 2m one . He got the results presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the chart?
1. normal pressure force N 2 = 2N 1
2. normal pressure force N 1 = N 2
3. coefficient of friction μ 2 = 2μ 1
4. coefficient of friction μ 1 = 2μ 2
3
. AT inertial system reference bar slides with acceleration down an inclined plane. Establish a correspondence between physical quantities and their possible changes wherein.
Write in the table the selected numbers under the corresponding letters. Numbers in the answer may be repeated.
4. A block in the form of a parallelepiped moves along the demonstration table. The first face of the bar has both the area and the coefficient of friction on the table 4 times greater than the area and coefficient of friction of the second face. If you turn the bar from the first side to the second, then the frictional force of sliding the bar on the table
1. will not change 2. will decrease by 4 times
3. decrease by 16 times 4. increase by 4 times
5. Body weight in air, measured with a dynamometer, is R one . What is the dynamometer reading R 2 if the body is in water and a buoyant force acts on it F?
1
.R 2 = R 1 2.R 2 = F 3. R 2 = R 1 + F 4.R 2 = R 1 – F
6. The student performed an experiment to measure the stretch X springs 1 and 2 when hanging loads from them. The results obtained by the student are presented in the figure in the form of a diagram. What is the conclusion about the stiffness of the springs k 1 and k 2 can be drawn from the chart analysis, if the weight of the load m 1 , suspended from the first spring, 2 times less than the mass m 2 weights suspended from the second spring ( m 2 = 2m 1)?
1
.k 1 = k 2 2.k 1 = 2k 2 3.k 2 = 2k 1 4.k 2 = 4k 1
7. The student performed an experiment to measure the friction force acting on two bodies moving along horizontal surfaces. Mass of the first body m 1 , mass of the second body m 2 , and m 1 = 2m 2. He got the results presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the chart?
1. normal pressure force N 2 = 2N 1
2. normal pressure force N 1 = N 2
3. coefficient of friction μ 1 = μ 2
4. coefficient of friction μ 2 = 2μ 1
8. An aluminum ball suspended from a thread is lowered into the water. Then the ball was taken out of the water. In this case, the tension force of the thread
1. will not change 2. will increase 3 
. decrease
4. may remain unchanged or change depending on the volume of the ball
9. The figure shows a graph of the speed modulus of a car moving straight along the road versus time. In which , acting on the car, is different from zero and is directed opposite to its movement?
3. 4 s to 8 s 4. 0 to 8 s
1
0. The student performed an experiment to measure the friction force acting on two equally processed bodies of the same material moving along the same horizontal surface. He got the results presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the chart?
1. normal pressure force N 2 = 2N 1 2. normal pressure force N 1 = 2N 2
3. coefficient of friction μ 2 = 2μ 1 4. coefficient of friction μ 1 = 2μ 2
11. Is it possible, being in a car with curtained windows with full soundproofing, with the help of some experiments to determine whether the train moves uniformly and rectilinearly or is at rest? Explain the answer.
1
2. The student performed an experiment to measure the stretch X springs 1 and 2 when hanging loads from them. The results obtained by the student are presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the diagram if loads of the same mass were suspended from the ends of the springs?
1. spring stiffness k 1 = k 2 2. spring rate k 1 = 2k 2
3. spring stiffness k 2 = 2k 1 4. spring rate k 2 = 4k 1
13. A block in the form of a parallelepiped moves along the demonstration table. At the first face of the bar, the coefficient of friction on the table is 2 times less than that of the second face. If you turn the bar from the first side to the second, then the frictional force of sliding the bar on the table
1. will not change 2. will decrease by 2 times
3. decrease by 4 times 4. increase by 2 times
1
4. The student performed an experiment to measure elongation X springs when hanging loads from them. The results obtained by the student are presented in the figure in the form of a diagram. What is the conclusion about the stiffness of the springs k 1 and k 2 can be drawn from the analysis of the diagram if loads of the same mass were suspended from the ends of the springs?
1.k 1 = k 2 2.k 1 = 2k 2 3.k 2 = 2 k 1 4. k 2 = 4k 1
15. An aluminum ball suspended from a thread is lowered into distilled water. Then the ball was transferred from distilled water to a strong solution of table salt. In this case, the tension force of the thread
1. will not change 2. will increase 3. will decrease
1
6. An aluminum ball suspended on a thread is lowered into a strong solution of table salt. Then the ball was transferred from the sodium chloride solution to distilled water. In this case, the tension force of the thread
1. will not change 2. will increase 3. will decrease
4. may remain unchanged or change depending on the volume of the ball
17. The figure shows two weights hanging on weightless threads. The mass of each weight is indicated in the figure. Thread tension force
1. at the point BUT equal to 3 N, at the point AT equal to 5 H 2. at the point BUT equal to 8 N, at the point AT equal to 2 N
3. at the point BUT equal to 8 N, at the point AT equals 5 H 4. at the point BUT equal to 3 N, at the point AT equal to 2 N
1
8. Pictured a graph of the dependence of the speed of the car, moving rectilinearly along the road, from time to time. In what time interval is the resultant of all forces acting on the car equal to zero?
1. 0 to 2 s 2. 2 s to 4 s
19. What is the work of the traction force acting on the car, if, starting to move from a state of rest uniformly accelerated with an acceleration of 1
1. 2 kJ 2. 10 kJ 3. 2000 kJ 4. 20000 kJ
20. Two bars of the same size lie at the bottom of the aquarium, which is filled with water. One bar is metal and with a flat bottom edge, the other is brick and porous. Are the values of the buoyant forces acting on the bars the same? Explain why.
2
1. Is the value of the buoyant force acting on a piece of wood with a volume of 100 cm3 and on a piece of iron of the same volume the same when they are completely immersed in water? Consider the case when neither iron nor wood is lowered to the bottom.
22. The figure shows a graph of the speed of a car moving straight along the road versus time. In what time interval is the resultant of all forces acting on the car equal to zero?
1. 0 to 2 s
2. 2 s to 4 s
3. 4 s to 8 s
4. in none of the time intervals is the resultant force equal to zero
23. The figure shows a graph of the speed of a car moving straight along the road versus time. In what time interval is the resultant of all forces acting on the car different from zero and co-directed to its speed?
1. 0 to 2 s 2. 2 s to 4 s
3. 4 s to 7 s 4. 0 to 7 s
24. The student investigated the dependence of the elongation of an elastic spring on the force applied to it, using 100-gram weights for this, and obtained the following data. After analyzing the obtained values, he made the following assumptions:
A. Hooke's law for a given spring is valid for the first three dimensions.
B. Hooke's law for a given spring is valid for the last three dimensions.
Which of the student's hypotheses is correct?
| m, G | 100 | 200 | 300 | 400 | 500 | 600 |
| Δl, cm | 2 | 4 | 6 | 7 | 9 | 11 |
1. only A 2. only B
3. both A and B 4. neither A nor B
2
5. It is necessary to establish experimentally whether the buoyancy force depends on the density of a body immersed in a liquid. What set of aluminum and copper cylinders can be used for this purpose?
1. only A 2. only B
3. only B 4. either A or B
2
6. The student performed an experiment to measure the force of friction, acting on two bodies of the same mass moving on different horizontal surfaces. He got the results presented in the figure in the form of a diagram. What conclusion can be drawn from the analysis of the chart?
1. normal pressure force N 2 = 2N 1
2. normal pressure force N 1 = 2N 2
3. coefficient of friction μ 2 = 2μ 1
4. coefficient of friction μ 1 = 2μ 2
27. Using a carriage (bar) with a hook, a dynamometer, one weight, a guide rail, assemble an experimental setup to measure the coefficient of sliding friction between the carriage and the surface of the rail.
On the answer sheet:
1) draw a drawing of the experimental setup;
2) write down the formula for calculating the coefficient of sliding friction;
3) indicate the results of measurements of the weight of the carriage with the load and the sliding friction force when the carriage with the load moves along the surface of the rail;
4) write down the numerical value of the coefficient of sliding friction.
28. An ice floe floating in a glass of fresh water was transferred to a glass of salt water. In this case, the Archimedean force acting on the ice
1. Decreased as density fresh water less than the density of salt
2. decreased, as the depth of immersion of the ice in the water decreased
3. increased because the density of salt water is higher than the density of fresh water
4. has not changed, since in both cases the buoyancy force balances the force of gravity acting on the ice floe
2
9. Needs to be experimentally verified, whether the buoyant force depends on the volume of the body immersed in water. Which of the indicated pairs of bodies can be used for such a check?
1. A and D 2. A and C 3. A and B 4. C and D
30. Body weight is measured by hanging it on a dynamometer. body weight in air R one . body weight in water R 2. What is the buoyant force acting on the body in water F?
1.F = R 1 2.F = R 2
3.F = R 1 + R 2 4.F = R 1 – R 2
31. A weightless inextensible thread is thrown through a fixed block, to the ends of which weights of equal mass are suspended m. What is the tension in the thread?
1. 0,25mg 2. 0,5 mg 3.mg 4. 2 mg
32. The student conducted an experiment to study the buoyancy force acting on a body completely immersed in a liquid, and for the experiment he used various liquids and solid cylinders of different volumes, made of different materials.
results experimental measurements cylinder volume V and buoyant force F Arch (indicating the measurement error) for various cylinders and liquids, he presented in the table.
Choose from the proposed list two statements that correspond to the results of experimental observations. List their numbers.
1. The buoyancy force does not depend on the density of the material of the cylinder.
2. The buoyancy force does not depend on the type of liquid.
3. The buoyancy force increases with an increase in the volume of the body.
4. The buoyancy force does not depend on the volume of the body.
5. The buoyant force acting on a body when immersed in oil is greater than the buoyant force acting on this body when immersed in water.
experience | Liquid | Cylinder material | V, cm 3 | F Arch, N |
|
| 1 | Water | Aluminum | 40 | 0.4 ± 0.1 |
|
| 2 | Butter | Aluminum | 90 | 0.8±0.1 |
|
| 3 | Water | Steel | 40 | 0.4 ± 0.1 |
|
| 4 | Water | Steel | 80 | 0.8±0.1 |
GIA-0 PHYSICS State (final) certification in PHYSICS Option No. 1125 Instructions for performing work To be completed examination work in physics, 3 hours (180 minutes) are allotted. The work consists of 3 parts and includes 25 tasks. Part I contains 18 tasks (1 -18). Each question has 4 possible answers, of which only one is correct. Part 2 includes 3 short answer tasks (19 -21). First, indicate the answers to the tasks of parts 1 and 2 on the sheets with the tasks of the examination paper, and then transfer them to form No. 1. If the task requires you to write down a sequence of numbers as an answer, when transferring the answer to the form, you should indicate only this sequence, without commas, spaces and other symbols. To correct the answers to the tasks of parts 1 and 2, use the fields of the form No. 1 in the area "Replacement of erroneous answers". Part 3 contains 4 tasks (22-25), which should be given a detailed answer. Answers to the tasks of part 3 are recorded on form No. 2. Task 22 is experimental, and for its implementation it is necessary to use laboratory equipment. When calculating, it is allowed to use a non-programmable calculator.
1 The body moves along the x-axis. The figure shows graphs of coordinates and projections of body velocity versus time. Which chart matches uniform motion?
2 The student performed an experiment to measure the tension x of springs 1 and 2 while hanging loads from them. The results obtained by the student are presented in the figure in the form of a diagram. What conclusion about the stiffness of the springs k 1 and k 2 can be drawn from the analysis of the diagram, if the mass of the load m 1 suspended from the first spring is 2 times less than the mass m 2 of the load suspended from the second spring (m 2 = 2 m 1)? 1) k 1 = 2 k 2 2) k 2 = 2 k 1, 3) k 2 = 4 k 1, 4) k 1 = k 2
3 A body is thrown vertically upwards. The figure shows a graph of the dependence of the kinetic energy of the body on its height above the point of throw. What is the total energy of the body at a height of 4 m relative to the point of throw? Ignore air resistance. 1) 1.5 J 2) 3 J 3) 6 J 4) 9 J
4 The lever is in equilibrium under the action of two forces. Force F 1 \u003d 5 N, force F 2 \u003d 8 N. What is the arm of force F 2 if the arm of force F 1 is 16 cm? 1) 10 cm 2) 16 cm 3) 26 cm 4) 25.6 cm
5 The figure shows three bodies of the same volume. It is known that the first body has the largest mass, and the third body - the smallest. Compare the densities of the substances (ρ1, ρ2 and ρ3) of which these bodies are made. 1) ρ1 > ρ2, ρ3 > ρ2 2) ρ1 ρ2 > ρ3 4) ρ1 = ρ2 = ρ3
6 A car of mass 500 kg accelerates from a standstill and reaches a speed of 20 m/s in 10 s. The resultant of all forces acting on the car is 1) 500 N 2) 1000 N 3) 2000 N 4) 4000 N
7 In the process of melting a crystalline substance 1) the internal energy of the substance decreases 2) the kinetic energy of the movement of molecules decreases 3) the internal energy of the substance increases 4) the kinetic energy of the movement of molecules increases
8 The figure shows a graph of the dependence of temperature solid body from the amount of heat given to them. Body weight 4 kg. What is the specific heat capacity of the substance of this body? 1) 500 J/(kg ∙ 0 C) 2) 250 J/(kg ∙ 0 C) 3) 125 J/(kg ∙ 0 C) 4) 100 J/(kg ∙ 0 C)
9 A light, uncharged metal foil ball is suspended from a thin silk thread. When a rod with a positive electric charge is brought to the ball (without touching), the ball 1) repels from the rod 2) experiences neither attraction nor repulsion 3) on long distances attracted to the rod, repelled at short distances 4) attracted to the rod
10 The figure shows a diagram of an electrical circuit containing two resistors connected in parallel with resistance R 1 and R 2. Which of the following relationships is true for such a connection of resistors? 1) U=U 1+U 2 2) I=I 1+I 2 3) R = R 1+R 2 4) I=I 1=I 2
11 A magnet is inserted into a coil connected to a galvanometer. The strength of the induction current depends A. on the speed of movement of the magnet B. on which pole the magnet is inserted into the coil The correct answer is 1) only A 2) only B 3) both A and B 4) neither A nor B
12 The object is at a distance of F/2 from the converging lens. What will be the image of the item? 1) direct, imaginary 2) inverted, real 3) there will be no image 4) direct, real
13 Electric stove, connected to a 220 V network. What energy does the stove consume in 20 minutes of operation if the current flowing through its spiral is 5 A? 1) 22 k. J 2) 110 k. J 3) 1320 k. J 4) 4840 k. J
15 The length of the bar is measured with a ruler. Record the result of the measurement, taking into account that the measurement error is equal to half the scale division. 1) 6.5 cm 2) (6.5± 0.5) cm 3) (6.0± 0.5) cm 4) (6.50± 0.25) cm
Foucault currents Consider the simplest experiment demonstrating the occurrence of an inductive current in a closed coil of wire placed in a changing magnetic field. It is possible to judge the presence of an induction current in a coil by heating the conductor. If, while maintaining the same external dimensions of the coil, it is made of a thicker wire, then the resistance of the coil will decrease, and the induction current will increase. The power released in the form of heat in the coil will increase. Induction currents when changing magnetic field also arise in massive metal samples, and not only in wire loops. These currents are usually called eddy currents, or Foucault currents, after the French physicist who discovered them. The direction and strength of the eddy current depend on the shape of the sample, on the direction and speed of the changing magnetic field, on the properties of the material from which the sample is made. In massive conductors, due to the smallness of the electrical resistance, the currents can be very large and cause significant heating.
If a massive iron core is placed inside the coil and an alternating current is passed through the coil, then the core heats up very strongly. To reduce heating, the core is made up of thin plates isolated from each other by a layer of varnish. Foucault currents are used in induction furnaces for intense heating and even melting of metals. To do this, the metal is placed in an alternating magnetic field created by a current with a frequency of 500-2000 Hz. The braking effect of Foucault currents is used to create magnetic dampers - dampers. If a massive copper plate is placed under a magnetic needle oscillating in a horizontal plane, then the Foucault currents excited in the copper plate will slow down the vibrations of the needle. Magnetic dampers of this kind are used in galvanometers and other instruments.
16 The strength of the eddy current that occurs in a massive conductor placed in an alternating magnetic field depends 1) only on the shape of the conductor 2) only on the material and shape of the conductor 3) only on the rate of change of the magnetic field 4) on the rate of change of the magnetic field, on the material and conductor shapes
17 In an alternating magnetic field, an iron core made of thin insulated plates will heat up 1) less, since its electrical resistance will be greater than a solid core, 2) more, since its electrical resistance will be less 3) more, since its electrical resistance will be greater 4) less, since its electrical resistance will be less
18 copper plate, suspended on a long insulating handle, oscillates freely. If the plate is deflected from the equilibrium position and released so that it enters with speed and into the space between the poles of the permanent magnet (see figure), then 1) the plate oscillations will abruptly damp out 2) the plate oscillation frequency will increase 3) the plate oscillation amplitude will increase 4) the plate , will perform the usual free oscillations
19 For each physical concept from the first column, select the appropriate example from the second column PHYSICAL CONCEPTS A) physical quantity B) unit of physical quantity C) physical device A B C EXAMPLES 1) ammeter 2) pendant 3) electromagnetic induction 4) electric charge 5) electric field
20 In the inertial frame of reference, the bar, which was given the initial speed V 0, begins to slide up the inclined plane (see figure). Establish a correspondence between physical quantities and their possible changes in this case. PHYSICAL QUANTITY A) speed of the bar B) potential energy of the bar C) total mechanical energy bar A B C CHARACTER OF CHANGE 1) increases 2) decreases 3) does not change
21 In the reference book of physical properties of various materials, the following table is presented. Using the data in the table, select two correct statements from the proposed list. Indicate their numbers.
21 1) With equal dimensions, an aluminum conductor will have a greater mass compared to a copper conductor. 2) Nichrome and brass conductors with the same dimensions will have different electrical resistances. 3) Constantan and nickel conductors with the same dimensions will have different masses. 4) When replacing a nickel-plated electric stove coil with a nichrome coil of the same size, the electrical resistance of the coil will increase. 5) With an equal cross-sectional area, a 1 m long iron conductor will have the same electrical resistance as a 4 m long nickeline conductor.
22 Assemble an experimental setup to determine the work of electric current performed on a resistor using a current source (4.5 V), a voltmeter, an ammeter, a key, a rheostat, connecting wires and a resistor marked R 2. Using a rheostat, set the current in the circuit to 0 , 5 A. Determine the work of the electric current in the resistor for 5 minutes. In the answer sheet: 1) draw the electrical circuit of the experiment; 2) write down the formula for calculating the work of an electric current; 3) indicate the results of voltage measurement at a current strength of 0.5 A; 4) write down numerical value work of electric current.
23 Which ship moves slower, loaded or unloaded, with the same engine power? Explain the answer.
24 Energy gained from cooling hot water from 100°C to 70°C, was only enough to melt 840 g of ice, taken at a temperature of 0°C. What was the mass of hot water? energy loss in environment neglect.
25 An electric lamp with a power of 40 W shines for 10 hours. What mass of water must pass through the dam of a hydroelectric power station (HPP) to ensure the operation of the lamp? The height of the dam is 20 m, the HPP efficiency is 90%.
