Quiz
Physics around us
“They go to battle
some experts! "
Quiz stages
- "Warm-up"
2 "Tell me, teacher ..."
3 "Obvious but incredible ..."
4 "Choose the right path"
(Experimental Teams)
5 "In the world of technology"
Warm up
What is physics?
This is science
about nature
Who first introduced the word "physics"?
Aristotle- ancient greek philosopher
Who created the first physics textbook?
M.V. Lomonosov
What does physics study?
Physical phenomena
Who discovered the phenomenon of inertia?
Galileo Galilei- italian scientist
A troika of horses was running. Each horse ran 5 km. How many kilometers did the coachman drive?
When does a kilogram weight have a large mass: in summer or in winter?
Equal mass
What is the basic unit of measure for strength?
Newton
IN honor of the English physicist Isaac Newton
What physical quantity is measured with a beaker?
Volume
Common name for the 12 constellations?
Zodiac
What is the largest planet?
Jupiter
(13 times the size of the Earth)
Where is the end of the world?
Where the shadow begins.
What instrument is used to measure atmospheric pressure?
Aneroid barometer
Where does the steamer sink deeper into the water: in the river or in the sea?
In a river
What device is used to measure speed?
Speedometer
What volume of 1 kg of water?
1 liter
It is said to flow like a river in only one direction.
Time
If it is, you don't need mind
Power
A specific unit for measuring the volume of oil?
1 barrel =
159 liters
What is 1 pood?
1 pood =
16 kilograms
There are 10 fingers on the hands, how many fingers are there on 10 hands?
50 fingers
Tell me, teacher ...
1. It is performed by all bodies, processes, thoughts.
2. This is what allows you to first be in one place, and then in another.
3. Without him there would be no life.
Motion
Tell me, teacher ...
- This "thing" is very small; it can move at a very high speed, or it can just swing.
2. It is found in all substances, but it is different in different substances.
3. It consists of atoms
Molecule
Tell me, teacher ...
- This can happen to anyone in life, in nature; sometimes by accident, sometimes on purpose.
2. If there is ice on the street, then this happens by accident, and if at a basketball game, then on purpose
3. Because the apple did it, Newton discovered the law.
The fall
Tell me, teacher ...
- Unusual oldest building with a height of about 60 meters.
2. One of the scientists carried out his experiments, being on top of it.
3. Located in the city of Pisa.
Leaning tower of pisa
Tell me, teacher ...
- There were about 3 thousand applicants for this trip, but the choice fell on him.
- What he accomplished glorified the human mind, himself and his homeland.
- He owns the historical phrase said before the start of the journey: “Let's go! ".
Yu.A. Gagarin
Tell me, teacher ...
- The first woman in Russia with the rank of major general.
- Pilot-cosmonaut in the USSR No. 6, 10 cosmonaut of the world.
- The only woman in the world who has committed space flight by oneself.
V.V. Tereshkova
Obvious but incredible ...
A pouring rain poured down, but why then did the colored rocker hang in the sky?
A rainbow occurs due to the refraction of light rays in raindrops. This proves the complex composition of the light.
Obvious but incredible ...
There is frost in the yard
Snow creaks underfoot.
Think about it, tell me
Why does it creak, tell me?
Snowflakes have a crystalline structure, and therefore the snow creaks underfoot, as hundreds of thousands of crystal snowflakes break.
Obvious but incredible ...
The smoke from the fire rises up
And it melts into darkness.
You are by the fire, you take a closer look:
Goes up ... Why?
The smoke from the fire is warm, less dense than the colder air, and is buoyant upward.
Obvious but incredible ...
White trail behind the plane
Seen in the blue heights
Why does it arise,
Who will answer me more precisely?
Airplane flying, throwing out hot smoke particles. Water vapor rapidly condenses and a cloud trail (fog) forms behind the aircraft.
Obvious but incredible ...
In balls and probes, we know in advance
Helium and hydrogen are used.
Why, tell me quickly
Then he runs upward faster?
Helium and hydrogen are lighter than air. (They have a lower density compared to air) Therefore, they rush upward.
Life or not life?
- Why are cotton or woolen laces loosened less often than silk laces?
- Experienced housewives, before pouring boiling water into a glass, lower a teaspoon. For what?
- What explains the fact that the dust does not fall even from the surface facing down?
- Freshly baked bread weighs more than cooled bread. Why?
- Why is it easier to cut with a sharp knife than a blunt one?
Obvious but incredible ...
I saw, I understood-
EXPLAIN
𝞾 \u003d 〈M / s〉 speed
𝞺 \u003d 〈Kg / m 3 〉 Density
m \u003d 〈Kg〉 mass
F = 〈Н〉 strength
S \u003d 〈m〉 path
V \u003d 〈m 3 〉 Volume
t = 〈 c 〉 time
Choose the right path
Find the right path
Ts.d. (Beakers) =
Ts.d. (Dynamometer) =
Ts.d. (Thermometer) =
Ts.d. (Ammeter) =
Find the right path
Body volume
Body mass
m \u003d kg
V \u003d 20 cm 3
Find the right path
Calculate body density
weight
Density =
volume
𝞺 =
Technical tour
A.S Popov
Technical tour
The first modern
tV 1938 year
VC. Zvorykin
Technical tour
First atomic
power station
1954,
obninsk
I.V. Kurchatov
Technical tour
The first launch of an artificial Earth satellite
1957 year
S.P. Korolev
Technical tour
First in space
Yu.A. Gagarin
Technical tour
The first nuclear-powered icebreaker "Lenin"
1959 g.
HELL. Alexandrov
Technical tour
First unmanned lunar landing using the Luna 9 space probe
USSR 1966
Technical tour
The world's first rover to reach the surface of Mars
USSR 1971
Technical tour
Modern rovers
RIAR Dimitrovgrad
1956 year
"Know the laws, solve problems and you will not know failure!"
Thanks for the great game!
6 round.
Assemble the electrical circuit for speed. The winner is the team with the fastest light on. (One person from the team participates, 5 points)
Extracurricular physics activity: intellectual game "Fizboy"
7 - 8 grade
Purpose of the game:Updating students' knowledge in the subject area "Physics", as well as identifying gifted students who are able to apply the knowledge gained in a non-standard situation.
Tasks:
to increase students' interest in physics, as one of the subjects of the natural science cycle;
stimulate the cognitive activity and creativity of students, their ingenuity, observation;
teach to apply knowledge in a new situation, as well as to correctly explain the occurring physical phenomena;
continue to develop and consolidate the skills of solving experimental, computational and qualitative problems;
to form students' communication skills, the ability to work in groups, the ability to assess the activities of a friend.
Equipment: two computers, two video projectors, instruments for the experiment.
Explanatory note:
The game involves several teams of 4-5 students in grade 8.
The game is directed by a teacher organizer. Members of the jury can be teachers of physics, mathematics, biology.
Before the competition, each team receives a written task and an answer form. The answer sheet is coded.
After completing each task, the teams transmit the results of their work through the assistant teachers to the members of the jury.
Game progress
The organizer teacher proposes assignments to team members using a computer presentation.
Competition number 1. "Blitz Poll".
Motto: "Hurry up, but don't be mistaken."
Each team is asked questions in turn, to which they give answers. You must answer quickly. If some team did not answer the question, then the team that first lit the light on the table has the right to answer. ( You can adjust the number of questions yourself).
Questions for round 1:
1.What can be cooked but not eaten? (lessons)
2. How many months in a year have 28 days? (all months)
3. What can travel the world while staying in the same corner? (Postage Stamp)
4. What gets bigger if you put it upside down? (number “6”)
5. Which hand is best for stirring tea? (it is better to do it with a spoon)
6. The dog was tied to a ten-meter rope and walked three hundred meters. How did she do it? (the rope was not tied to anything)
7. In which city does blood flow? (in Vienna)
8. Which female name has two letters that are repeated twice? (Anna)
9. Which car wheel does not rotate while driving? (spare)
10. What belongs to you, yet others use it more than you do? (name)
11. What question cannot be answered “yes”? (Are you sleeping?)
12. What is the only bird capable of flying tail first? (hummingbird)
13. What is the name of the unit used to measure the force of gravity? (newton)
14. In what language was the word “algebra” first spoken? (In the Arabic language)
15. Making which product never succeeds on the first try? ( the first pancake is lumpy)
16. What substance under terrestrial conditions can exist in three states of aggregation? (water)
17. What is three to the third degree? (27)
18. What is the name of the animated version of the story by Kir Bulychev "Alice's Journey"? ("The Mystery of the Third Planet")
19. Who was the first to prove the theorem on aspect ratios in a right triangle? (Pythagoras)
20. What is the name of the fourth letter of the Greek alphabet? (delta)
ADDITIONAL QUESTIONS:
1. What is the sum of the interior angles of a quadrilateral? (360
0
)
2. What is the name of a regular four gon? (square)
3. What professions have 5 parallel lines constantly before their eyes? (musicians, stave)
4. What is the name of the sixth note? (la)
5. What will the correct hexagon be called in the language of geometry? (hexahedron, cube)
6. What is the angle of the hour hands when the clock is 6 o'clock? (180
0
)
7. What prefix do physicists and mathematicians usually use when seeing the number 10 6? (mega)
8. What is the name of the most large constellation in the sky of the Northern Hemisphere, consisting of 7 stars visible to the eyes? (Big Dipper)
9. What is the only galaxy that can be seen in the starry sky of the Northern Hemisphere with the naked eye? (Andromeda's nebula)
0. What procedure folk wisdom advises to do 7 times before doing another one? (Measure 7 times and cut once)
11. What instrument will the piano and accordion combine? (accordion)
12. What musical instrument do many shamans use during cult rituals? (tambourine)
13. What is the name of the Russian three-stringed plucked instrument? (balalaika)
14. What are the names of graphic signs for recording musical sounds? (notes)
15. What sign should be placed between the numbers 5 and 6 to get a number greater than five but less than six? (comma)
16. To increase the number 666 one and a half times, without performing any arithmetic operations? (flip)
17. What number is divisible by all numbers without a remainder? (0)
18. When are the dividend and the quotient equal? (when the divisor is 1)
19. There are two fathers and two sons in one family. How many people are there in the family? (three persons)
20. The purpose of solving the equation? (find the answer)
Competition number 2. Labyrinth "Physical quantities"
12 names known to you are encrypted in the labyrinth physical quantities... You can read in any direction except diagonals.
Answers to competition number 2: time, heat capacity, pressure, power, force, density, work, temperature, mass, path, speed, weight.
Competition number 3. "Well-known meter ..."
The word "meter" ends with physical measuring devices used not only in the laboratories of scientists, in the physical room of the school, but also at home, in cars, workshops, photo laboratories ...
You are invited to find as many measuring instruments as possible ending with this word, and indicate what they are measuring.
For instance: thermometer - temperature
Answers to competition # 3:
dynamometer - strength;
meter - length;
speedometer - speed;
barometer - atmospheric pressure;
manometer - pressure;
hygrometer, psychrometer - air humidity;
electrometer - electric charge;
ammeter - current strength;
voltmeter - voltage;
wattmeter - power, etc.
Competition number 4. "Physical riddles"
Each correct answer brings 1 point to the team.
He will tell everything, albeit without language, when it will be clear, and when - clouds. (Barometer)
Swirls, not smoke, falls, not snow ... (Fog)
Books are read, but they do not know letters . (Glasses)
There was one Antoshka, he looked out the window - there is another Antoshka! What is this window? Where was Antoshka looking? (Mirror)
Hanging pear - you can't eat . (Light bulb)
What can't you pick up from the ground? (Shadow)
Apparently she has no mind: she eats herself. (Candle)
Pure and clear like a diamond, there are no roads, it is born of a mother , gives birth to it himself . (Ice)
In the evening it flies to the ground, the night remains on the ground, in the morning it flies again. (Dew)
A plate hangs on the wall, An arrow walks along the plate. This arrow ahead of us knows the weather. (Barometer)
Competition number 5. "Do you agree that ..."
Write “yes” or “no” next to the questions.
Each correct answer brings 1 point to the team.
Does the water vapor appear as white clubs? (no)
Is the specific heat of combustion of gunpowder less than that of kerosene? (Yes)
Does cold water put out a fire faster than boiling water? (no)
Does a full kettle cool more slowly than an incomplete kettle? (Yes)
Is the Earth's South Pole in Antarctica? (no)
Is the appearance of lift in a moving wing of an airplane explained by the action of Ohm's law? (no)
Is the air humidity measured with a hygrometer? (Yes)
... the nucleus of an atom contains electrons, protons, neutrons? (no)
... usually on the bulb of an electric lamp that shines in each of you in the apartment, indicate its electrical parameters - current strength, voltage, power? (no)
... the words armature, rotor and stator refer to the rotating parts of an electrical machine? (no)
Competition number 6. Physics Experts
Give answers to questions (each correct answer brings 1 point to the team):
Will the melting of ice in a warm room speed up if you cover the ice with a fur coat? (No, a fur coat does not heat, it has poor thermal conductivity, slows down the flow of heat to the ice and eliminates convection)
A drop of water, hitting on a hot stove, begins to jump on it. Why? (A hot plate, heating the surface of the drop, forms a shell of steam around it, this steam throws the drop up)
Why do wet fingers freeze to metal objects in winter and do not freeze to wooden ones? (Metal, having a higher thermal conductivity than wood, removes heat from a thin film of water so quickly that it cools below its melting point and freezes.)
Which burns more: the steam escaping from the spout of a boiling kettle, or the spray of water itself? ( The steam burns much more strongly, because the skin gives off the heat generated by the condensation process.)
Why does the frost (hoarfrost) on trees sometimes disappear without a thaw? (Rime, or frost, is water in a crystalline state; it evaporates at any temperature.)
If in May or September it was clear during the day and the sky was covered with clouds in the evening, should we expect a frost at night? (No, because clouds block the Earth's radiation of heat rays, and there is no significant drop in temperature at the Earth's surface.)
The amount of heat received from the sun's rays during the year by the Arctic is much greater than that received by the same area in the Crimea. Why is it hot in Crimea in summer and cold in the Arctic? (Because in the Arctic, most of the radiant energy delivered by the sun's rays is not absorbed, but reflected back by the snow.)
Why does snow creak underfoot in the cold? (Hundreds of crystal snowflakes break)
Why, when transporting flammable liquids, a chain is attached to the body of a tanker truck, which drags along the ground when driving? (When transported in tank trucks, flammable liquids are agitated and electrified. To avoid sparks and fires, a circuit is used that conducts the charges to the ground.)
Why is it advisable to install fuses in all electrical appliances? (It is easier to replace a fuse that burns out when the current exceeds the permissible value than an important part - when it burns out, the fuse opens the electrical circuit.)
Competition No. 7. "Let's overtake on the task"
Problem number 1
Water weighing 10 kg is poured into an aluminum tank weighing 2 kg. How much heat is required to heat a water tank from 20 ° C to 100 ° C? (Specific heat capacity of aluminum - 920 J / kg ° С, specific heat capacity of water - 4200 J / kg ° С)
c al \u003d 920 J / kg ° С
c in \u003d 4200 J / kg ° С
Q 1 \u003d c al m 1 * (t 2 - t 1) \u003d 920 * 2 * (100 - 20) \u003d 147200J
Q 2 \u003d c in m 2 * (t 2 - t 1) \u003d 4200 * 10 * (100 - 20) \u003d 3360000J
Q \u003d Q 1 + Q 2 \u003d 147200 + 3360000 \u003d 3507200J \u003d 3507 kJ
Competition number 8. "Who will win?"
Write formulas for calculating the physical quantities known to you (grade 7-8).
Formulas composed of the same physical quantities are evaluated as one formula at 1 point.
For instance:ρ \u003d m / V, m \u003d ρV, V \u003d m / ρ (1 b)
Competition number 9. "Riddles with hints"
Riddle 1.
1. There were many applicants for the trip, but the choice fell on him.
2. He made this round the world trip alone.
3. The son of a peasant, a student of a vocational school, a worker, a cadet of an aeroclub.
4. He owns the historical phrase "Let's go!", Said before the start.
5. The first person in the world to fly into space. (gagarin)
Riddle 2.
1. He lived in the 4th century. BC.
2. He was the tutor of Alexander the Great.
3. His teachings apply to all areas of knowledge of the time.
4. His teaching dominated science for about 100 years.
5. He introduced the word "physics" into science. (Aristotle)
Riddle 3.
1. He was one of the first scientists to work for the war.
2.He is a major inventor who lived before our era.
3. He invented the lever.
4.We come across one of his discoveries regularly while bathing in the bathroom.
5. According to legend, he owns the exclamation “Eureka!”, Which sounded after the discovery he made. (Archimedes)
1. The name of the first female astronaut? (Valentina Tereshkova)
2. When was the first space satellite launched? (1957)
3. What instrument is used to measure pressure? (barometer)
4. According to legend, he owns the exclamation "Eureka!", Which sounded after the discovery? (Archimedes)
5. How to speed up the diffusion process in solids? (by heating)
6. Why is the dirt road slippery after rain? (water is a lubricant).
7. Transfer of matter from liquid state into solid? (crystallization or solidification)
8. What instrument is used to measure the work of the current? (counter)
9. Why does a match ignite when its head is rubbed against the boxes? (friction increases the internal energy, i.e. temperature).
10. Spacecraftthat revolves around the earth? (satellite)
11. Who speaks all languages? (echo)
12. Which planet was discovered only in 1930? (Pluto)
13. In what SI units is the mass of an atom measured? (kg)
14. Will the mass of water change when some of it turns into ice? (no).
15. How many protons are in a water molecule? (18)
16. The weight was lowered into a vessel with water. Has the weight of the weight changed? (no).
17. What was Lomonosov's name? (Mikhail Vasilievich)
18. Doesn't sink in water and doesn't burn in fire? (ice)
19. What geometric shape represents the Earth? (ball)
20. By what number should 2 be divided to get 4? (0.5)
21. What thermal process is accompanied by a decrease in temperature? (evaporation)
22. The main astronomical observation device? (telescope)
23. Under normal conditions, one egg is boiled until "tough" for 4 minutes. How many minutes do you need to cook 5 eggs? (4 minutes)
24. What's going on without moving? (time)
25. Which planet is the largest? (Jupiter)
26. World space? (Universe)
27. Natural satellite Earth? (moon)
28. Aircraft with a jet engine? (rocket)
29. The common name of the 12 constellations? (zodiac)
30. Who flaps their wings more often in flight: a bumblebee or a mosquito? (mosquito)
Summarizing.
The jury calculates the points scored for the game by each team, announces the winners.
Results protocol intellectual game "Fizboy"
| Command code | Number of points for competitions | Total points | A place |
||||||||||
Description of work: the material will be useful for physics teachers when conducting extracurricular activities for students in grades 8-9 within the subject decade.
goal: development of cognitive interest in the subject;
Tasks:
Promote the deepening and generalization of knowledge in physics;
Develop the ability to think logically, reason, establish causal relationships, conduct an experiment;
To instill in students interest and attention to the world around them.
Physics quiz "Physical Kaleidoscope"
1. When you need to pour juice from a tin can through the hole in the lid, then make another hole. Only then is there a good stream. Why?
2. The acceleration of the rocket increases even if the resultant of the forces applied to it remains unchanged. Why?
3. How can an astronaut who is not connected to the spacecraft return to the spacecraft?
4. What is the physical error in the next poem?
She lived and flowed on the glass,
But suddenly she was bound with frost,
And the drop became a motionless piece of ice,
And there was less warmth in the world.
5. Given two exactly identical long iron rods. One of them is magnetized. How to determine which rod is magnetized without using any other objects.
6. A ball 4 cm in diameter fell into a tall cylindrical vessel 5 cm in diameter. Can you reach the ball without turning the vessel?
7. Why does dirty, sooty snow melt faster than clean snow?
8. Does the friction force always slow down the movement of the body? Can friction be the driving force?
9. How to pour water out of a bottle without tilting it?
10. Why does it get quiet after a snowfall?
Answers to the quiz questions:
1. If you make only one hole in the lid of the can and overturn the can. The juice will be poured out until the pressure inside the liquid at the level of the hole is equal to atmospheric. When there are two holes in the lid. That is the air. Getting into the jar through the "free" hole. Provides additional pressure on the liquid and "pushes" it.
2. The acceleration increases due to the decrease in the mass of the rocket.
3. Throwing away from yourself in the direction opposite to the ship, Any object.
4. When water crystallizes, heat, on the contrary, is released.
5. Let rod 1 be magnetized. If in this case we bring its end to the middle of rod 2, the rods will be attracted. And if you bring the end of rod 2 to the middle of rod 1, the rods will not be attracted.
6. Pour water into the vessel. The ball will float up and can be removed.
7. Black bodies are better at absorbing heat radiation.
8. Maybe. For instance. In diesel locomotives, cars, motorcycles, the traction force is the friction force of the driving wheels on the rails and the roadbed. The objects on the conveyor belt are driven and moved by friction.
9. Introduce air through the tube passed into the bottle. In this case, the air pressure in the bottle will increase and it will squeeze some of the water out through the same tube.
10. There are small cavities between the fluffs of freshly fallen snow. Which absorb sound just like modern sound-absorbing coatings.
Physics assignments
Task number 1
Psychics often demonstrate the phenomenon of so-called biomagnetism. It manifests itself in the fact that after pressing metal objects, such as coins, to the forehead, the latter remain on the person for a long time. Psychics claim that the holding time of a coin is related to the intensity of the thinking process. Suggest an explanation for this phenomenon, given that such an experience can be repeated by almost anyone.
A Coin sticks to skin secretions
B The coin heats up and diffuses into the skin
The coin is held magnetic fieldarising from mental activity
D Electrification and electrostatic attraction occurs between the skin and the coin.
D Gravitational force the attraction of a coin to a person is greater than the force of its attraction to the Earth
Adhesion is caused by the mutual attraction of the particles that make up the coin to the molecules of substances on the skin. A.
Task number 2
In areas with snowy winters, during thaws, wooden roofs of houses are sometimes pushed through and collapsed under the influence of snow. And how does the gravity force acting on the snow on the roof change as it melts? When reasoning, do not take into account the flow of melted snow from the roof, the change in the height of the center of gravity of the melting snow (and even the relationship between mass and energy, expressed in Einstein's formula).
A Decreases
B Does not change
Increases many times
D Increases approximately one and a half to two times
The force of gravity acting on a body depends on its mass, but does not depend on the state of aggregation. When the snow melts, its mass does not change, so the gravity force acting on it does not change either. B.
Task number 3
The Chinese called them chu-shi, the Greeks - Adamas, the Herculean stone, the French - Ayman, the Egyptians - the Ora bone, the Germans - Magness, the British - Loudstone. Most of these names mean loving. What (or who) is said in such a poetic language of the ancients?
Answer: Magnet.
Task 4.
This scientist is one of the famous physicists of antiquity. He is credited with the phrase: "Give me a fulcrum, and I will move the Earth" Who are we talking about?
Answer: the ancient Greek scientist Archimedes.
Task 5.
How do you explain Plutarch's statement?
"Amber contains a fiery and incorporeal force that comes out of it in hidden ways, if you rub the surface of amber ..."
Answer: When rubbed, the amber surface is electrified. An electrified body is capable of attracting other bodies and creating a spark discharge.
Why do cranes and other birds keep in schools during long flights?
Answer. The most powerful bird is ahead. The air flows around it, like water the bow of a ship, a wedge forms behind it, inside which weaker birds experience less air resistance.
A bullet, hitting a boiled egg, pierces it, leaving a hole, and a raw egg is shattered by a bullet. Why?
Answer. A boiled egg (especially the yolk) has a slight elasticity, the pressure in it increases little when the bullet passes. In a raw egg, as in a liquid (elastic medium), the pressure rises instantly and very strongly.
Why is it difficult to clap your hands underwater?
Answer. When they move slowly, little water is carried away by them, and when they move quickly, the water does not have time to "part" (there is an "attached mass").
№ 4.
Why can moose walk in snow or swamp without getting stuck?
Answer. Elk is a cloven-hoofed animal. There is a membrane between the forked parts of the hooves (when the parts of the hooves move apart, the support area increases, the pressure on the soil, the snow decreases).
№ 5.
Why is it more difficult to pull carrots and other root vegetables out of dense soil than from loose soil?
Answer. Under the root crop, when pulled out, a vacuum is formed (pressure less than atmospheric). The denser the soil, the greater the vacuum.
Why do people have more joint dislocations high in the mountains than below?
Answer. At altitude, the pressure is reduced, the force of pressing against each other of the bones articulated in the joint becomes less, and dislocations of the joints occur more often.
Why do tea leaves gather in the center of the glass when tea is stirred?
Answer. The higher the speed, the lower the pressure in the moving fluid. The speed is lower near the edges of the glass (due to the friction of water on the glass). The excess pressure between the center and the edges of the glass moves the tea leaves towards the center.
Why does a fish need a swim bladder?
Answer. By squeezing and stretching it with muscles, fish regulate the volume, which means the density of their body. Compression - decrease in volume - increase in density - immersion (and vice versa).
Why do freezing people and animals tremble?
Answer. So they get warm. Movements are made - mechanical work is performed - internal energy rises.
On hot days, it is cooler in a deciduous forest than in a coniferous forest. Why?
Answer. Trees evaporate moisture from the leaf surface. At the same time, the internal energy of the leaves decreases (they are cooled) and the air cools. Deciduous trees have more leaf surface area - more evaporation - more cooling.
Why doesn't a leaning bike fall over when cornering?
Answer. To move in a circle, action is required centripetal force... It occurs when the bike is tilted.
In the experiment with "Magdeburg plates" Otto Kerike harnessed 8 horses on the left and 8 horses on the right. How could the same number of horses develop more traction?
Answer. Fix one plate, and 16 horses to the other (the force of action is equal to the force of reaction).
Boiling water extinguishes a fire faster than cold water (immediately takes away the heat of vaporization from the flame and surrounds the fire with a layer of steam, which impedes the access of air).
Is it possible to pump boiling water directly into the flame with pumps?
Answer. No. In the pump under the piston, instead of the discharged air, there will be steam with an elasticity of 1 atm. Boiling water will not flow into the hoses.
In the pipes of underground parts of buildings, water often freezes not in frost, but in a thaw in spring. Why?
Answer. Thermal conductivity is carried out slowly in the ground (low thermal conductivity coefficient).
Wood conducts sound better than air. Why is the conversation in the next room drowned out when the door to the room is closed?
Answer. “At the boundary” of air-wood, sound passes from an environment that is poorly conductive of sound (compared to wood) to an environment that conducts sound quickly (wood). There is a limiting angle of incidence for sound beams. Much of the sound waves must be reflected back into the air.
What nationalities were Celsius, Reolif and Fahrenheit?
Answer. Swede, French, German.
Why is intense heat more difficult to tolerate in swampy places than in dry ones?
Answer. In swampy areas, the relative humidity is high, sweat evaporates poorly, and the skin cools slowly.
Drops are falling from the tap of the samovar. When are these droplets heavier: when is the water hot or when it has cooled?
Answer. When the water has cooled down, because with decreasing temperature, the surface tension coefficient increases and the drop becomes larger.
How will an electrified stick act on a magnetic needle? Why?
Answer. The end of the arrow will be attracted to the electrified stick, because induced charges will appear on the steel arrow.
№ 20.
“Rye, rye ... Field road
Leads to no one knows where.
Sagging low over the steppe,
The wires groan lazily ... "
(A. Tvardovsky)
Why are the wires humming?
Answer. When air flows around the wires, "vortices" are formed behind them. The pressure in vortices is less than where there are none. Whirlwinds "break" from the wires and "sound".
Why do electrostatic instruments have no sharp ends?
Answer. The charge density is greater where the surface curvature is greater (at the tip). Near the tip, the air is ionized and neutralizes its charge ("charge drains"). To keep the charge, the surface is made round, smooth.
An electrified soap bubble inflates so much that its radius increases significantly (the charge does not change). How will the charge energy change? Does the charge help or hinder the inflation of the bubble?
Answer. The charge energy will decrease (Wp \u003d Q2 / 2R); it is easier to inflate a charged bubble, because the charges repel each other and contribute to an increase in the free surface.
In 1822, Arago noticed that a magnetic needle, oscillating about the equilibrium position, quickly stops if it is in a copper case. Why?
Answer. The swinging magnetic needle creates an alternating magnetic field. It induces eddy currents in copper, the direction of which is such that they impede the movement of the arrow with their fields.
If you hit one end of a long metal pipe with a hammer, the person at the other end of the pipe will hear a double blow. Why?
Answer. The first blow is a sound wave against metal, the second - in the air.
Water is poured into the bottle. The jet of water produces a noise of a certain tone. As the bottle is filled with water, this tone becomes higher. Why?
Answer. The cavity of the bottle is a resonator. As the bottle fills, the length of the resonator column decreases. The pitch increases.
If you rub the balloon of a neon lamp, you will notice that it glows for a short time. How to explain this phenomenon?
Answer. As a result of friction, charges appear on the glass, the field of which causes a short-term glow of the lamp.
How should the two converging lenses be positioned so that the beam of parallel rays passing through both lenses becomes parallel again?
Answer. So that their main focuses coincide.
Why do the windows of houses appear dark during the day, i.e. darker than the outside walls, even if they are (walls) painted with dark paint?
Answer. Reflection of light from walls is always greater than reflection from transparent ones, i.e. letting in light, windows.
Lenz Emily Khristianovich - Russian physicist. In what area of \u200b\u200bphysics did he carry out his main work? What exactly are his main works related to?
Answer. In the field of electromagnetism. Lenz's law on the direction of the induction current.
Huygens Christian is a Dutch physicist. In what area of \u200b\u200bphysics is his work known?
Answer. In the field of mechanics, optics. Huygens' formula for the period of harmonic oscillations of a physical pendulum. Huygens' principles in explaining the mechanism of light propagation.
"Dark night.
Only bullets whistle across the steppe,
Only the wind hums in the wires
Dimly the stars twinkle. "
(V. Agatov)
Why do the stars twinkle?
Answer. The reason is in the properties of the earth's atmosphere. Now here and there there are clots, then discharges. The pressure is changing too. Air density "jumps" together with the pressure. Through such areas, light cannot propagate in a straight line. Light from a star, passing through the earth's atmosphere, experiences numerous and random deflections. That's why the star flickers.
A negatively charged body is brought to a positively charged electroscope. What happens then?
Answer. First, the angle between the leaves decreases, then \u003d 0 and then increases.
№ 33.
Indicate as many similarities and differences as possible between electric and gravitational fields.
Answer.
Similarities:
1) analogy of interaction of charges and masses (laws of Coulomb and Newton);
2) both fields are conservative (work on a closed path is zero);
3) the existence of a potential difference in them.
Differences:
1) there are no negative masses;
2) there are no gravitationally neutral bodies.
Why are powder stores surrounded by grounded metal mesh?
Answer. There is no electric field inside the metal mesh, no electric spark arises.
Why doesn't he electrocute a bird that sits on one of the high voltage wires?
Answer. The potential difference between the legs is small, the current is small.
How does the current change in the circuit with a carbon lamp and a lamp with a metal filament immediately after switching on?
Answer. In the second, as the filament is heated, the current decreases (resistance increases). In coal it is the other way around.
Pieces of copper, iron and nickeline wire of the same diameter and length are included in the current circuit. Which pieces will get hotter:
a) with a serial connection;
b) with parallel?
Answer
a) nickelin, iron, copper (as the resistance decreases);
b) copper, iron, nickelin (as the current decreases).
To determine the sign of the poles of the source, lower the wires connected to the source into a glass of water and observe which of the wires produces more gas. How is it determined which pole is negative?
Answer. During electrolysis of water, the volume of released hydrogen is 2 times the volume of oxygen. The negative pole will be the one with more gas (hydrogen, whose ions are positive).
When current flows through electrolytes, they heat up. Why?
Answer. Ions in electrolytes move at an accelerated rate when current flows. In collisions, the energy (kinetic) of ordered motion is converted into energy of chaotic (thermal) motion.
How will the breakdown voltage of the gas gap change (increase or decrease) with decreasing gas pressure?
Answer. The lower the pressure, the longer the mean free path, the higher the kinetic energy of the ion accumulates, the higher the probability of ionization at the same (or lower) voltage. The breakdown voltage decreases with decreasing pressure.
Experience shows that it is impossible to charge infinitely any body and that, after the charge on the body reaches a certain maximum value, depending on the size and shape of the body and properties environment further increase in charge cannot be achieved. Why?
Answer. With enough tension electric field a discharge (corona or spark) occurs around the body in the surrounding dielectric (air) and the air loses its insulating properties.
An iron cube lying on a smooth glass is attracted to a magnet also lying on this glass. The cube slides on the glass. How does it move (what is the nature of its movement)?
Answer. The force acting on the cube increases as it approaches the magnet. Cube movement with increasing acceleration.
Which of the cathode rays are deflected more strongly by the same magnetic field: faster or slower?
Answer. Faster electrons are deflected more (the Lorentz force is directly proportional to the charge speed of the electrons that make up the cathode rays).
When the current from one or more batteries is closed, a spark does not work, but when it is opened, it does. Why?
Answer. When turned on, the EMF of induction is directed against the EMF of the circuit, and when turned off - in the same direction with it (Lenz's law).
The pendulum is made of a vessel of water suspended from a long string. The water is gradually poured out through the hole in the bottom of the vessel. How will the period of the pendulum change (we neglect the mass of the vessel)?
Why is there a sharp deafening blow at close lightning, and a rolling thunder at a distant lightning?
Answer. When close, the primary sound wave from the lightning itself is many times stronger than the echo that comes later from reflecting objects. With a distant one, the primary and reflected waves reach us with less differing strength
Two identical particles, but one fast and the other slow, move in a circle in the same magnetic field. Which of the particles rotates faster?
Answer. The turnover time does not depend on the particle velocity. (m / qBp 2 \u003d t)
№ 48.
The plane mirror is rotated at an angle of 30 degrees about an axis lying in the plane of the mirror and perpendicular to the incident beam. At what angle will the reflected beam turn?
Answer. 60 degrees.
№ 49.
How quickly can you determine the center of gravity of a uniform stick weighted at one end?
Answer. Place it on the index fingers of the left and right hands. Bring your fingers together. They will converge under the center of gravity of the stick.
№ 50.
Where does the steamer plunge deeper into the water: in the river or in the sea? Why?
Answer. In a river. The density of salt water is greater than that of fresh water. In the sea of \u200b\u200bArchimedes, strength increases.
№ 51.
What is the action of the current used in electric welding?
Answer. Thermal.
№ 52.
Why is the insulation destroyed in the place of poor conductor contact?
Answer. the conductor in this place is warming up.
№ 53.
What forces are called conservative?
Answer. Their work on a closed loop is zero.
№ 54.
How can the direction of rotation of an electric motor armature be changed?
Answer. By changing the direction of the current in the armature or inductor winding
№55
In winter, metal is colder to the touch than wood outside. How will metal and wood feel to the touch in forty-degree heat?
Answer. The thermal conductivity of metal is much higher than that of wood, so in winter the metal will be colder to the touch, and hotter than wood in the heat.
№56
Why can't you use an electromagnet to carry hot blanks?
Answer. Because iron, heated to 800 °, is not magnetized at all.
№57
Why is the stream bubbling?
Answer. The stream gurgles because the stream of water, with a slight fall, captures air particles and immerses them in water, which causes bubbles to form. The bursting of these bubbles explains the murmur of the brook
№58
What are the composite tones of white?
Answer. White color is a mixture of seven different colors of the spectrum; red, orange, yellow, green, blue, blue, purple.
№59
What is the common property that distinguishes honey and cast iron from most other substances?
Answer. They, unlike most substances, do not increase during melting, but decrease in volume.
№60
What wood would you take for a kerosene barrel?
Answer. For a kerosene barrel, you need to take a palm tree or an oak tree, because in relation to these materials, kerosene has the property of non-wetting, that is, the adhesion between kerosene molecules is greater than between kerosene and oak or palm molecules, and kerosene does not seep through the capillaries of oak and palm trees.
№61
Why are water pipes sometimes wet outside?
Answer. The air around the pipes is cooled and condenses on the surface of the pipes.
№62
In order to better see your face in the evening and in the mirror, where will you put the lamp in front of you or behind you?
Answer. The lamp should be in front of you, between you and the mirror.
№63
What do you think is heavier: a ton of wood or a ton of iron?
Answer. A ton of wood will, oddly enough, heavier than iron. If you recall, Archimedes' law applies not only to liquids, but also to gases. Each body "loses" from its weight in the air as much as the displaced volume of air weighs. Wood and iron also lose some of their weight in the air. But a ton of wood takes up much more volume than a ton of iron, every 15 times, so the true weight of a ton of wood is greater than the weight of a ton of iron.
№64
How fast must the car move for the red light of the semaphore to appear green to the driver?
Answer. This task is a joke. For this to be true, the car must move at a speed close to the speed of light, that is, do 300,000 kilometers per second.
№65
What kind of molten metal freezes water?
Answer. Mercury.
№66
What metals float in water?
Answer. Potassium. Sodium. Magnesium.
№67
What metal writes like a pencil?
Answer. Lead.
How fast should the dog run so as not to hear the ringing of the frying pan tied to its tail?
ANSWER
Physics immediately reveals this problem in the company: the physicist immediately replies that she needs to run at supersonic speed. Of course, the dog only needs to stand still.
There is a light bulb in the room. Outside the room, there are 3 switches, one of which turns on this light, while the others do not work. You need to find out which of them turns on the light bulb, and you can enter the room only once. (The switches click in the same way, you cannot disassemble, the door to the room closes tightly, you cannot see anything in the keyhole, etc.)
ANSWER
(We leave the first switch off.
We turn on the second.
Turn on the third, WAIT, turn off.
Let's go to see what's with the light bulb. On - means the second switch, off - touch with your hand: warm means the third switch, cold means the first)
Glasses on paper. There are 2 glasses on the table at some distance from each other (15-20cm). There is a sheet (A4) that needs to be put on these 2 glasses and on top of it put a third glass (between two) so that the sheet does not bend to the table).
ANSWER
(you need to fold a sheet of paper with an accordion, and the glass will stand)
Coffee with milk A very useful task. You can write out equations for a long time, but you can understand that the answer is obvious ... There are two identical glasses, in which it is poured equally: in one - milk, in the other - coffee. A spoonful of milk is poured from the first glass into a glass of coffee. Then they stir, and a spoonful of coffee with milk is poured from the second glass back into the first one. What is more now: milk in coffee or coffee in milk?
ANSWER
(the same milk content in coffee and coffee in milk)
Try this trick: fill a clean glass to the top with water and argue with the guests that there is still a lot of free space in the glass. Of course, they will not believe you, but you will begin carefully, without touching the water, but without splashing, to lower coins into the glass one after another. And at the same time, the water will not pour out of the glass - you will prove that there is still room in it! Why does this happen?
ANSWER
(If you look at the glass from the side, you will see how, when the coins are lowered, its surface swells with a bump: water does not pour out, since it is held by a film of surface tension)
What has no length, depth, width, height, but can be measured?
ANSWER
(Time, temperature)
Who can travel the world while staying in the same corner?
ANSWER
(postage stamp on the envelope)
When is the day shorter: winter or summer?
ANSWER
(a day is always 24 hours)
There are two buckets filled with water on the two scales of the beam balance. The water level in them is the same. A wooden block floats in one bucket. Will the balance balance?
ANSWER
(Yes, they will. Any floating body displaces with its submerged part as much liquid (by weight) as this body weighs)
When there was no central heating and hot water heaters yet, bath water was heated on a stove. In those days, a cook once heated water on the stove in a large saucepan to refill the bathtub, where there was already some water at room temperature. Noticing this, the butler said to her: "Don't you understand that the longer you heat the water on the stove, the colder the water in the bath will be when you pour the heated water into it?" He was right. Why?