What physical phenomena are mechanical. Natural phenomena

Topic: General concepts about dangerous and emergency situations of a natural nature.

Lesson topic: Natural phenomena and their classification.

The purpose of the lesson: To acquaint students with natural phenomena and their diversity.

Lesson objectives:

I. Educational tasks:

• Recall and consolidate knowledge about the shells of the Earth.
• To form students' knowledge that the formation of any natural phenomenon is associated with the processes occurring in the Earth's shells.
• To give a general idea to students about the types of natural phenomena at the place of their occurrence.

II. development tasks.

• To develop in students the ability and ability to foresee the natural phenomena of their area, which can lead to serious consequences, as well as ways to protect against them.

III. educational tasks.

• Instill in students the belief that any a natural phenomenon destructive power brings enormous damage to the state different kind, primarily material and loss of life. Therefore, the state needs to send funds to scientific institutions so that they deal with this problem and be able to predict them in the future.

During the classes

Teacher: Today, children, we will talk about natural phenomena and their diversity. Of course, you know some, some you learned from the course of natural history and geography, and if someone is interested in means mass media then from there. If you turn on the TV, radio or use the Internet, then we can say with confidence that natural phenomena of destructive power are occurring more and more often, and their strength is becoming greater. Therefore, we need to know what natural phenomena occur, where they occur most often and how to protect ourselves from them.

Teacher: And so let's remember from the course of geography what shells of the Earth exist.

In total, 4 shells of the Earth are distinguished:

1. Lithosphere - it includes the earth's crust and the upper part of the mantle.
2. The hydrosphere is a water shell, it includes all water in different states.
3. The atmosphere is a gas shell, the lightest and most mobile.
4. The biosphere is the sphere of life, it is the area of ​​existence of all living organisms.

Teacher: In all these shells, certain processes take place, as a result of which natural phenomena arise. Therefore, various natural phenomena can be divided according to the place of their occurrence:

Teacher: From this diagram, we see how many natural phenomena exist. Now let's look at each of them and find out what they are. (Children should take an active part in this part.)

Geological.

1. An earthquake is a natural phenomenon associated with geological processes occurring in the Earth's lithosphere, it manifests itself in the form of tremors and vibrations earth's surface resulting from sudden displacements and ruptures in the earth's crust or in the upper part of the mantle.

Picture 1.

2. A volcano is a conical mountain, from which an incandescent substance, magma, erupts from time to time.

A volcanic eruption is the release of the planet's surface of the molten substance of the earth's crust and mantle, which is called magma.

Figure 2.

3. A landslide is a downward displacement of soil masses under the action of gravity, which occurs on slopes when the stability of the soil or rocks is disturbed.

The formation of landslides depends on various factors such as:

• what rocks make up this slope;
• slope steepness;
• ground water, etc.

Landslides can occur both naturally (eg earthquake, heavy rainfall) and man-made (eg human activities: deforestation, excavation).

Figure 3

4. A collapse is a detachment and fall of large masses of rocks, their overturning, crushing and rolling on steep and steep slopes.

Causes of landslides in the mountains can be:

• the rocks that make up the mountains are layered or broken by cracks;
• water activity;
• geological processes (earthquake), etc.

Causes of collapses on the coast of seas and rivers are the washing and dissolution of the underlying rocks.

Figure 4

5. An avalanche is a collapse of a mass of snow on mountain slopes, the slope angle must be at least 15 °.

Reasons for leaving snow avalanche are:

• earthquake;
• intensive snow melting;
• prolonged snowfall;
• human activity.

Figure 5

Meteorological.

1. A hurricane is a wind whose speed exceeds 30 m/s, resulting in huge destruction.

Figure 6

2. A storm is a wind, but with a lower speed than in a hurricane and is no more than 20 m/s.

Figure 7

3. Tornado - is atmospheric vortex, formed in a thundercloud and descending, has a head start of a funnel or sleeve.

A tornado consists of a core and a wall. Around the core there is an upward movement of air, the speed of which can reach 200 m / s.

Figure 8

Hydrological.

1. Flooding is a significant flooding of the area as a result of a rise in the water level in a lake, river, etc.

Reasons for the flood:

• intensive snowmelt in spring;
• heavy rainfall;
• blockage of the riverbed rocks during an earthquake, collapse, etc., as well as ice during traffic jams;
• wind activity (water surge from the sea, bay at the mouth of the river).

Types of floods:

Figure 9

2. Mudflow is a stormy stream in the mountains of a temporary nature, consisting of water and a large number fragments of rocks.

The formation of mudflows is associated with abundant precipitation in the form of rain or intense snowmelt. As a result, loose rocks are washed away and move along the river bed with high speed, which picks up everything in its path: boulders, trees, etc.

Figure 10.

3. Tsunami is a type of sea waves resulting from the vertical shift of large areas of the seabed.

A tsunami occurs as a result of:

• earthquakes;
• underwater volcano eruptions;
• landslides, etc.

Figure 11.

Biological.

1. A forest fire is an uncontrolled burning of vegetation, spontaneously spreading through a forest area.

Forest fire can be: grassroots and riding.

An underground fire is the burning of peat in marshy and swampy soils.

Figure 12.

2. An epidemic is the spread of an infectious disease among a large number of the population and significantly exceeds the incidence rate usually recorded in the area.

Figure 13.

3. An epizootic is a widespread infectious disease among animals (for example: foot-and-mouth disease, swine fever, bovine brucellosis).

Figure 14.

4. Epiphytotics are mass distribution infectious disease among plants (for example: late blight, wheat rust).

Figure 15.

Teacher: As you can see, in the world there is great amount phenomena that surround us. So let's remember them and be extremely careful at the time of their occurrence.

Some of you may say: “Why do we need to know all of them if they are not typical for our region?”. From one point of view you are right, but from the other you are wrong. Each of you tomorrow, the day after tomorrow or in the future will surely go on a trip to other parts of the Motherland and the country. And there, as you know, there can be completely different phenomena that are not typical for our area. And then your knowledge will help you survive in a critical situation and avoid negative consequences. As the saying goes: "God saves the safe."

Literature.

1. Smirnov A.T. Fundamentals of life safety. 7th grade.
2. Shemanaev V.A. Teaching practice in the system of modern teacher training.
3. Smirnov A.T. The program of educational institutions of the basics of life safety grades 5-11.

Everything that surrounds us: both living and inanimate nature, is in constant motion and is constantly changing: planets and stars move, it rains, trees grow. And a person, as we know from biology, constantly goes through some stages of development. Grinding grains into flour, falling stone, boiling water, lightning, glowing light bulbs, dissolving sugar in tea, movement Vehicle, lightning, rainbows are examples physical phenomena.

And with substances (iron, water, air, salt, etc.) various changes or phenomena occur. The substance can be crystallized, melted, crushed, dissolved and again separated from the solution. However, its composition will remain the same.

So, granulated sugar can be ground into a powder so fine that at the slightest breath it will rise into the air like dust. Sugar specks can only be seen under a microscope. Sugar can be divided into even smaller parts by dissolving it in water. If water is evaporated from the sugar solution, the sugar molecules will again combine with each other into crystals. But when dissolved in water, and when crushed, sugar remains sugar.

In nature, water forms rivers and seas, clouds and glaciers. During evaporation, water turns into steam. Water vapor is water in the gaseous state. When exposed low temperatures(below 0˚С) water turns into a solid state - it turns into ice. The smallest particle of water is a water molecule. The water molecule is also the smallest particle of steam or ice. Water, ice and steam are not different substances, but the same substance (water) in different states of aggregation.

Like water, other substances can be transferred from one state of aggregation into another.

Characterizing this or that substance as a gas, liquid or solid, they mean the state of matter in normal conditions. Any metal can not only be melted (translated into a liquid state), but also turned into a gas. But this requires very high temperatures. In the outer shell of the Sun, metals are in a gaseous state, because the temperature there is 6000 ° C. And, for example, carbon dioxide can be turned into "dry ice" by cooling.

Phenomena in which there is no transformation of one substance into another are referred to as physical phenomena. Physical phenomena can lead to a change, for example, in the state of aggregation or temperature, but the composition of substances will remain the same.

All physical phenomena can be divided into several groups.

Mechanical phenomena are phenomena that occur with physical bodies when they move relative to each other (the revolution of the Earth around the Sun, the movement of cars, the flight of a parachutist).

Electrical phenomena are phenomena that arise during the appearance, existence, movement and interaction of electric charges (electric current, telegraphy, lightning during a thunderstorm).

Magnetic phenomena are phenomena associated with the occurrence of physical bodies magnetic properties(magnet attraction of iron objects, turning the compass needle to the north).

optical phenomena- these are phenomena that occur during the propagation, refraction and reflection of light (rainbow, mirages, reflection of light from a mirror, the appearance of a shadow).

Thermal phenomena are phenomena that occur when physical bodies are heated and cooled (melting snow, boiling water, fog, freezing water).

Atomic phenomena are phenomena that occur when there is a change internal structure substances of physical bodies (glow of the Sun and stars, atomic explosion).

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Ticket number 1

1. What does physics study. Some physical terms. Observations and experiments. Physical quantities. Measurement of physical quantities. Accuracy and error of measurements.

Physics is the science of the most general properties bodies and phenomena.

How does a person know the world? How does he investigate the phenomena of nature, receiving scientific knowledge about him?

The very first knowledge a person receives from observations behind nature.

To get the right knowledge, sometimes simple observation is not enough and you need to conduct experiment - a specially prepared experiment .

Experiments are carried out by scientists premeditated plan with a specific purpose .

During the experiments measurements are taken by using special devices physical quantities. Examples physical quantities are: distance, volume, speed, temperature.

So the source physical knowledge are observations and experiments.

Physical laws are based and tested on facts established by experience. An equally important way of knowing theoretical description of the phenomenon . Physical theories make it possible to explain known phenomena and predict new ones that have not yet been discovered.

Changes that occur with bodies are called physical phenomena.

Physical phenomena are divided into several types.

Types of physical phenomena:

1. Mechanical phenomena (for example, the movement of cars, aircraft, celestial bodies, fluid flow).

2. Electrical phenomena (for example, electric current, heating of conductors with current, electrization of bodies).

3. Magnetic phenomena (for example, the effect of magnets on iron, the effect magnetic field Earth on the compass needle).

4. Optical phenomena (for example, the reflection of light from mirrors, the emission of light rays from various light sources).

5. Thermal phenomena (melting ice, boiling water, thermal expansion bodies).

6. Atomic phenomena (for example, work nuclear reactors, decay of nuclei, processes occurring inside stars).

7. Sound phenomena (bell ringing, music, thunder, noise).

Physical terms are special words used in physics for brevity, definiteness and convenience.

Physical body is every object that surrounds us. (Showing physical bodies: pen, book, school desk)

Substance It is everything that physical bodies are made of. (Showing physical bodies consisting of different substances)

Matter- this is everything that exists in the Universe regardless of our consciousness (celestial bodies, plants, animals, etc.)

physical phenomena are changes that occur to physical bodies.

Physical quantities are the measurable properties of bodies or phenomena.

Physical Instruments- These are special devices that are designed to measure physical quantities and conduct experiments.

Physical quantities:
height h, mass m, path s, speed v, time t, temperature t, volume V, etc.

Units of measurement of physical quantities:

International system SI units:

(international system)

Main:

Length - 1 m - (meter)

Time - 1 s - (second)

Weight - 1 kg - (kilogram)

Derivatives:

Volume - 1 m³ - (cubic meter)

Velocity - 1 m/s - (meter per second)

In this expression:

number 10 - numerical value time

the letter "s" is an abbreviation for the unit of time (seconds),

and the combination of 10 s is the time value.

Prefixes to unit names:

To make it easier to measure physical quantities, in addition to basic units, multiple units are used, which are in 10, 100, 1000, etc. more basic

g - hecto (×100) k - kilo (× 1000) M - mega (× 1000 000)

1 km (kilometer) 1 kg (kilogram)

1 km = 1000 m = 10³ m 1 kg = 1000 g = 10³ g

Dynamic change is built into nature itself. Everything changes in one way or another every moment. If you look closely, you will find hundreds of examples of physical and chemical phenomena that are quite natural transformations.

Change is the only constant in the universe

Ironically, change is the only constant in our universe. In order to understand physical and chemical phenomena (examples in nature are found at every turn), it is customary to classify them into types, depending on the nature of the end result caused by them. There are physical, chemical and mixed changes, which contain both the first and the second.

Physical and chemical phenomena: examples and meaning

What is a physical phenomenon? Any change that occurs in a substance without changing it chemical composition, are physical. They are characterized by changes in physical attributes and financial condition(solid, liquid or gaseous), density, temperature, volume that occur without changing its fundamental chemical structure. There is no creation of new chemical products or changes in the total mass. In addition, this type of change is usually temporary and in some cases completely reversible.

When you mix chemicals in the lab, you can easily see the reaction, but there are many chemical reactions going on in the world around you every day. A chemical reaction changes molecules, while a physical change only rearranges them. For example, if we take chlorine gas and metallic sodium and combine them, we get table salt. The resulting substance is very different from any of its constituent parts. This is a chemical reaction. If we then dissolve this salt in water, we simply mix the salt molecules with the water molecules. There is no change in these particles, it is a physical transformation.

Examples of physical changes

Everything is made up of atoms. When atoms combine, different molecules are formed. The different properties that objects inherit are the result of different molecular or atomic structures. The main properties of an object depend on their molecular arrangement. Physical changes occur without changing the molecular or atomic structure of objects. They simply transform the state of an object without changing its nature. Melting, condensation, volume change and evaporation are examples of physical phenomena.

Additional examples of physical changes: metal expanding when heated, sound transmission through air, water freezing into ice in winter, copper being drawn into wires, clay forming on various objects, ice cream melting to a liquid, heating metal and changing it into another form, sublimation of iodine when heating, the fall of any object under the influence of gravity, the ink is absorbed by chalk, the magnetization of iron nails, a snowman melting in the sun, glowing incandescent lamps, magnetic levitation of an object.

How to distinguish between physical and chemical changes?

Many examples of chemical and physical phenomena can be found in life. It is often difficult to tell the difference between the two, especially when both can occur at the same time. To identify physical changes, ask the following questions:

• Is the state of an object's state a change (gaseous, solid, and liquid)?
• Is the change a purely limited physical parameter or characteristic such as density, shape, temperature, or volume?
• Is the chemical nature of an object a change?
• Are there chemical reactions that lead to the creation of new products?

If the answer to one of the first two questions is yes, and there are no answers to the subsequent questions, it is most likely a physical phenomenon. Conversely, if the answer to any of the last two questions is yes, while the first two are no, then it is definitely a chemical phenomenon. The trick is just to clearly observe and analyze what you see.

Examples of chemical reactions in everyday life

Chemistry takes place in the world around you, not just in the laboratory. Matter interacts to form new products through a process called chemical reaction or chemical change. Every time you cook or clean, it's chemistry in action. Your body lives and grows through chemical reactions. There are reactions when you take medicine, light a match and sigh. Here are 10 chemical reactions in Everyday life. This is just a small selection of those examples of physical and chemical phenomena in life that you see and experience many times every day:

1. Photosynthesis. Chlorophyll in plant leaves converts carbon dioxide and water into glucose and oxygen. It is one of the most common daily chemical reactions and also one of the most important because it is how plants produce food for themselves and animals and convert carbon dioxide into oxygen.
2. Aerobic cellular respiration is a reaction with oxygen in human cells. Aerobic cellular respiration is the opposite process of photosynthesis. The difference is that energy molecules combine with the oxygen we breathe to release the energy our cells need, as well as carbon dioxide and water. The energy used by cells is chemical energy in the form of ATP.
3. Anaerobic respiration. Anaerobic respiration produces wine and other fermented foods. Your muscle cells perform anaerobic respiration when you run out of oxygen, such as during intense or prolonged exercise. Anaerobic respiration by yeast and bacteria is used for fermentation to produce ethanol, carbon dioxide and other chemical substances that produce cheese, wine, beer, yogurt, bread and many other common foods.
4. Combustion is a type of chemical reaction. This is a chemical reaction in everyday life. Every time you light a match or a candle, light a fire, you see a combustion reaction. Incineration combines energy molecules with oxygen to produce carbon dioxide and water.
5. Rust is a common chemical reaction. Over time, the iron develops a red, flaky coating called rust. This is an example of an oxidation reaction. Other everyday examples include the formation of verdigris on copper and the tarnishing of silver.
6. Mixing chemicals causes chemical reactions. Baking powder and baking soda perform similar functions in baking, but they react differently to other ingredients, so you can't always swap them out. If you combine vinegar and baking soda for a chemical "volcano" or milk with baking powder in a recipe, you are experiencing a double bias or metathesis reaction (plus a few others). The ingredients are recombined to produce carbon dioxide gas and water. Carbon dioxide forms bubbles and helps the "growing" of baked goods. These reactions appear simple in practice, but often involve multiple steps.
7. Batteries are examples of electrochemistry. Batteries use electrochemical or redox reactions to convert chemical energy into electrical.
8. Digestion. Thousands of chemical reactions take place during digestion. As soon as you put food in your mouth, an enzyme in your saliva called amylase begins to break down sugars and other carbohydrates into more simple shapes that your body can absorb. The hydrochloric acid in your stomach reacts with food to break it down, and enzymes break down proteins and fats so they can be absorbed into the bloodstream through the intestinal wall.
9. Acid-base reactions. Whenever you mix an acid (such as vinegar, lemon juice, sulfuric acid, hydrochloric acid) with an alkali (e.g. baking soda, soap, ammonia, acetone), you are performing an acid-base reaction. These processes neutralize each other, producing salt and water. Sodium chloride is not the only salt that can be formed. For example, here is the chemical equation for an acid-base reaction that produces potassium chloride, a common substitute for table salt: HCl + KOH → KCl + H 2 O.
10. Soap and detergents. They are purified by chemical reactions. Soap emulsifies dirt, which means that oily stains bind to the soap so that they can be removed with water. Detergents reduce the surface tension of water, so they can interact with oils, sequester them, and wash them away.
11. Chemical reactions in food preparation. Cooking is one big hands-on chemistry experiment. Cooking uses heat to evoke chemical changes in food. For example, when you boil an egg hard, the hydrogen sulfide produced by heating the egg white can react with the iron from the egg yolk, forming a grey-green ring around the yolk. When you cook meat or baked goods, the Maillard reaction between amino acids and sugars produces a brown color and desirable flavor.

Other examples of chemical and physical phenomena

Physical properties describe characteristics that do not change the substance. For example, you can change the color of paper, but it's still paper. You can boil water, but when you collect and condense the steam, it's still water. You can determine the mass of a sheet of paper and it's still paper.

Chemical properties are those that indicate how a substance reacts or does not react with other substances. When sodium metal is placed in water, it reacts violently to form sodium hydroxide and hydrogen. Sufficient heat is generated by the hydrogen escaping into the flame by reacting with the oxygen in the air. On the other hand, when you put a piece of copper metal into water, there is no reaction. In this way, chemical property sodium is that it reacts with water, while the chemical property of copper is that it does not.

What other examples of chemical and physical phenomena can be given? Chemical reactions always occur between electrons in the valence shells of the atoms of elements in periodic table. Physical phenomena at low energy levels simply involve mechanical interactions - random collisions of atoms without chemical reactions, such as atoms or gas molecules. When the collision energies are very high, the integrity of the nucleus of atoms is broken, leading to division or fusion of the species involved. Spontaneous radioactive decay usually considered a physical phenomenon.

We are surrounded by an infinitely diverse world of substances and phenomena.

It is constantly changing.

Any changes that occur to bodies are called phenomena. The birth of stars, the change of day and night, the melting of ice, the swelling of buds on trees, the flashing of lightning during a thunderstorm, and so on - all these are natural phenomena.

Recall that bodies are made up of substances. Note that in some phenomena the substances of bodies do not change, while in others they change. For example, if you tear a piece of paper in half, then, despite the changes that have occurred, the paper will remain paper. If the paper is burned, it will turn into ashes and smoke.

Phenomena in which the size, shape of bodies, the state of substances can change, but substances remain the same, do not change into others, are called physical phenomena(evaporation of water, the glow of an electric bulb, the sound of strings musical instrument etc.).

Physical phenomena are extremely diverse. Among them are distinguished mechanical, thermal, electrical, lighting and etc.

Let's remember how clouds float across the sky, an airplane flies, a car drives, an apple falls, a cart rolls, etc. In all of these phenomena, objects (bodies) move. Phenomena associated with a change in the position of a body in relation to other bodies are called mechanical(translated from the Greek "mehane" means machine, tool).

Many phenomena are caused by the change of heat and cold. In this case, the properties of the bodies themselves change. They change shape, size, the state of these bodies changes. For example, when heated, ice turns into water, water into steam; When the temperature drops, steam turns into water, water into ice. The phenomena associated with the heating and cooling of bodies are called thermal(Fig. 35).

Rice. 35. Physical phenomenon: the transition of matter from one state to another. If you freeze drops of water, ice will reappear

Consider electrical phenomena. The word "electricity" comes from Greek word"electron" amber. Remember that when you quickly take off your woolen sweater, you hear a slight crackle. If you do the same in complete darkness, you will also see sparks. This is the simplest electrical phenomenon.

To get acquainted with another electrical phenomenon, do the following experiment.

Tear off small pieces of paper and place them on the table surface. Comb clean and dry hair with a plastic comb and bring it to the pieces of paper. What happened?

Rice. 36. Small pieces of paper are attracted to the comb

Bodies that are capable of attracting light objects after rubbing are called electrified(Fig. 36). Lightning during a thunderstorm auroras, electrification of paper and synthetic fabrics - all these are electrical phenomena. Operation of telephone, radio, TV, various household appliances are examples of human use of electrical phenomena.

Phenomena that are associated with light are called light. Light comes from the sun, stars, lamps, and some living things, such as fireflies. Such bodies are called luminous.

We see when light hits the retina. We cannot see in absolute darkness. Objects that do not themselves emit light (for example, trees, grass, the pages of this book, etc.) are visible only when they receive light from some luminous body and reflect it from their surface.

The moon, which we often speak of as a night star, is in reality only a kind of reflector of sunlight.

By studying the physical phenomena of nature, a person has learned to use them in everyday life, everyday life.

1. What are called natural phenomena?

2. Read the text. List what natural phenomena are called in it: “Spring has come. The sun is getting hotter. Snow melts, streams run. Buds swelled on the trees, rooks flew in.

3. What phenomena are called physical?

4. From the physical phenomena listed below, write down the mechanical phenomena in the first column; in the second - thermal; in the third - electrical; in the fourth - light phenomena.

Physical phenomena: lightning flash; snow melting; coast; melting of metals; operation of an electric bell; rainbow in the sky; sunbeam; moving stones, sand with water; boiling water.