Changes that occur with bodies are called physical phenomena. Natural phenomena. Examples of explainable and inexplicable phenomena

1. Diffusion. We encounter this phenomenon in the kitchen all the time. Its name is derived from the Latin diffusio - interaction, dispersion, distribution. This is the process of mutual penetration of molecules or atoms of two adjacent substances. The rate of diffusion is proportional to the cross-sectional area of ​​the body (volume), and the difference in concentrations and temperatures of the substances being mixed. If there is a temperature difference, then it determines the direction of propagation (gradient) - from hot to cold. As a result, spontaneous equalization of the concentrations of molecules or atoms occurs.

This phenomenon can be observed in the kitchen when odors spread. Thanks to the diffusion of gases, sitting in another room, you can understand what is being prepared. As is known, natural gas It is odorless and an additive is added to it to make it easier to detect domestic gas leaks. An odorant, such as ethyl mercaptan, adds a sharp unpleasant odor. If the burner does not light up the first time, then we can smell a specific smell, which we have known since childhood as the smell of household gas.

And if you throw grains of tea or a tea bag into boiling water and do not stir, you can see how the tea infusion spreads in volume clean water. This is the diffusion of liquids. An example of diffusion in a solid would be the pickling of tomatoes, cucumbers, mushrooms or cabbage. Salt crystals in water disintegrate into Na and Cl ions, which, moving chaotically, penetrate between the molecules of substances in vegetables or mushrooms.

2. Change of state of aggregation. Few of us have noticed that in a glass of water left, after a few days, the same part of the water evaporates at room temperature as when boiled for 1-2 minutes. And when we freeze food or water for ice cubes in the refrigerator, we don’t think about how this happens. Meanwhile, these most ordinary and frequent kitchen phenomena are easily explained. A liquid has an intermediate state between solids and gases. At temperatures other than boiling or freezing, the attractive forces between molecules in a liquid are not as strong or weak as in solids and gases. Therefore, for example, only receiving energy (from sunlight, air molecules at room temperature) liquid molecules from the open surface gradually pass into the gas phase, creating vapor pressure above the liquid surface. The rate of evaporation increases with increasing surface area of ​​the liquid, increasing temperature, and decreasing external pressure. If the temperature is increased, the vapor pressure of this liquid reaches external pressure. The temperature at which this occurs is called the boiling point. The boiling point decreases as the external pressure decreases. Therefore, in mountainous areas, water boils faster.

Conversely, when the temperature drops, water molecules lose kinetic energy to the level of attractive forces between themselves. They no longer move chaotically, which allows the formation crystal lattice like solids. The temperature of 0 °C at which this occurs is called the freezing point of water. When water freezes, it expands. Many may have become familiar with this phenomenon when they placed a plastic bottle with a drink in the freezer for quick cooling and forgot about it, and then the bottle burst. When cooled to a temperature of 4 °C, there is first an increase in the density of water, at which its maximum density and minimum volume are achieved. Then, at temperatures from 4 to 0 °C, the bonds in the water molecule are rearranged, and its structure becomes less dense. At a temperature of 0 °C, the liquid phase of water changes to the solid phase. After water completely freezes and turns into ice, its volume increases by 8.4%, which leads to expansion plastic bottle. The liquid content of many products is low, so they do not increase in volume as much when frozen.

3. Absorption and adsorption. These two almost inseparable phenomena, named from the Latin sorbeo (to absorb), are observed, for example, when heating water in a kettle or pan. A gas that has no chemical effect on a liquid can nevertheless be absorbed by it upon contact with it. This phenomenon is called absorption. When gases are absorbed by solid fine-grained or porous bodies, most of them accumulate tightly and are retained on the surface of the pores or grains and are not distributed throughout the entire volume. In this case, the process is called adsorption. These phenomena can be observed when boiling water - bubbles separate from the walls of a pan or kettle when heated. The air released from water contains 63% nitrogen and 36% oxygen. But in general atmospheric air contains 78% nitrogen and 21% oxygen.

Table salt in an uncovered container may become moist due to its hygroscopic properties - the absorption of water vapor from the air. And soda acts as an adsorbent when it is placed in the refrigerator to remove odors.

4. Manifestation of Archimedes' law. Once we're ready to cook the chicken, we fill the pot about halfway or ¾ full with water depending on the size of the chicken. When immersing the carcass in a pan of water, we notice that the weight of the chicken in the water noticeably decreases, and the water rises to the edges of the pan.

This phenomenon is explained by buoyant force or Archimedes' law. In this case, a body immersed in a liquid is subject to a buoyancy force equal to the weight of the liquid in the volume of the immersed part of the body. This force is called the Archimedes force, as is the law itself that explains this phenomenon.

5. Surface tension. Many people remember experiments with films of liquids, which were shown in physics lessons at school. A small wire frame with one movable side was dipped into soapy water and then pulled out. Surface tension forces in the film formed around the perimeter lifted the lower movable part of the frame. To keep it motionless, a weight was hung from it when the experiment was repeated. This phenomenon can be observed in a colander - after using it in the holes in the bottom of this kitchen utensils water remains. The same phenomenon can be observed after washing forks - on inner surface There are also streaks of water between some of the teeth.

The physics of liquids explains this phenomenon as follows: the molecules of a liquid are so close to each other that the forces of attraction between them create a surface tension in the plane of the free surface. If the force of attraction of the water molecules of the liquid film is weaker than the force of attraction to the surface of the colander, then the water film breaks. Surface tension forces are also noticeable when we pour cereal or peas, beans, or add round grains of pepper into a pan of water. Some grains will remain on the surface of the water, while most will sink to the bottom under the weight of the rest. If you lightly press the floating grains with your fingertip or spoon, they will overcome the surface tension of the water and sink to the bottom.

6. Wetting and spreading. On a kitchen stove with a grease film, spilled liquid can form small spots, and on the table - one puddle. The thing is that in the first case, liquid molecules are more strongly attracted to each other than to the surface of the plate, where there is a fatty film not wetted by water, and on a clean table, the attraction of water molecules to the molecules of the table surface is higher than the attraction of water molecules among themselves. As a result, the puddle spreads out.

This phenomenon also relates to fluid physics and is related to surface tension. As you know, a soap bubble or liquid drops have a spherical shape due to surface tension forces. In a drop, liquid molecules are attracted to each other more strongly than to gas molecules, and tend to move inside the liquid drop, reducing its surface area. But, if there is a solid wetted surface, then part of the drop upon contact is stretched along it, because the molecules of the solid attract the molecules of the liquid, and this force exceeds the force of attraction between the molecules of the liquid. The degree of wetting and spreading over a solid surface will depend on which force is greater - the force of attraction between liquid molecules and solid molecules between themselves or the force of attraction of molecules inside the liquid.

Since 1938, this physical phenomenon has been widely used in industry, in the production of household goods, when Teflon (polytetrafluoroethylene) was synthesized in the DuPont laboratory. Its properties are used not only in the manufacture of non-stick cookware, but also in the production of waterproof, water-repellent fabrics and coatings for clothes and shoes. Teflon is noted in the Guinness Book of Records as the most slippery substance in the world. It has very low surface tension and adhesion (sticking), is not wetted by water, fats, or many organic solvents.

7. Thermal conductivity. One of the most common phenomena in the kitchen that we can observe is the heating of a kettle or water in a saucepan. Thermal conduction is the transfer of heat through the movement of particles when there is a difference (gradient) in temperature. Among the types of heat conduction there is also convection. In the case of identical substances, liquids have less thermal conductivity than solids and more than gases. The thermal conductivity of gases and metals increases with increasing temperature, and that of liquids decreases. We encounter convection all the time, whether we stir soup or tea with a spoon, or open a window, or turn on the ventilation to ventilate the kitchen. Convection - from the Latin convectiō (transfer) - a type of heat transfer when internal energy gas or liquid is transmitted by jets and streams. There are natural and forced convection. In the first case, layers of liquid or air mix themselves when heated or cooled. And in the second case, mechanical mixing of the liquid or gas occurs - with a spoon, fan or other method.

8. Electromagnetic radiation. A microwave oven is sometimes called an ultra-high frequency oven, or microwave oven. The main element of every microwave is a magnetron, which converts electrical energy into microwave energy. electromagnetic radiation up to 2.45 gigahertz (GHz). The radiation heats the food by interacting with its molecules. Products contain dipole molecules containing positive and negative electrical charges on their opposite parts. These are molecules of fats, sugar, but most of all dipole molecules are in water, which is found in almost any product. The microwave field, constantly changing its direction, causes molecules to vibrate at high frequencies, which are lined up along the lines of force so that all the positively charged parts of the molecules “look” first in one direction or the other. Molecular friction occurs and energy is released, which heats the food.

9. Induction. In the kitchen you can increasingly find induction cookers, the basis of which is this phenomenon. English physicist Michael Faraday discovered electromagnetic induction in 1831 and since then it has been impossible to imagine our lives without it. Faraday discovered the occurrence of an electric current in a closed circuit due to a change in the magnetic flux passing through this circuit. There is a well-known school experience when a flat magnet moves inside a spiral-shaped wire circuit (solenoid), and a electricity. There is also a reverse process - an alternating electric current in a solenoid (coil) creates an alternating magnetic field.

A modern induction cooker works on the same principle. Under the glass-ceramic heating panel (neutral to electromagnetic vibrations) of such a plate there is an induction coil through which an electric current flows with a frequency of 20-60 kHz, creating an alternating magnetic field that induces eddy currents in a thin layer (skin layer) of the bottom of the metal cookware. Due to electrical resistance, the cookware heats up. These currents are no more dangerous than hot cookware on conventional stoves. The cookware must be steel or cast iron with ferromagnetic properties (attract a magnet).

10. Refraction of light. Angle of light incidence equal to angle reflections, and the propagation of natural light or light from lamps is explained by the dual, corpuscular-wave nature: on the one hand, it electromagnetic waves, and on the other hand, photon particles that move at the highest speed possible in the Universe. In the kitchen you can observe such an optical phenomenon as the refraction of light. For example, when there is a transparent vase of flowers on the kitchen table, the stems in the water seem to shift at the boundary of the water surface relative to their continuation outside the liquid. The fact is that water, like a lens, refracts the rays of light reflected from the stems in the vase. A similar thing can be seen in a transparent glass of tea with a spoon in it. You can also see a distorted and enlarged image of beans or cereals at the bottom of a deep pan of clear water.

Ticket No. 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 understand the world? How does he explore natural phenomena, obtaining scientific knowledge about him?

A person receives his very first knowledge from observations behind nature.

To obtain the correct knowledge, sometimes simple observation is not enough and you need to carry out experiment – ​​specially prepared experiment .

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

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

So, the source of physical knowledge is observations and experiments.

Physical laws are based and verified on facts established experimentally. An equally important way of knowing is theoretical description of the phenomenon . Physical theories make it possible to explain known phenomena and predict new, not yet discovered ones.

Changes that occur to 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, airplanes, celestial bodies, fluid flow).

2. Electrical phenomena (for example, electric current, heating of current-carrying conductors, electrification of bodies).

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

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

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

6. Atomic phenomena (for example, the operation of atomic reactors, nuclear decay, processes occurring inside stars).

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

Physical terms- these are special words that are used in physics for brevity, certainty and convenience.

Physical body– this is every object around us. (Showing physical bodies: pen, book, desk)

Substance- this is all that they are made of physical bodies. (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- these are changes that occur with physical bodies.

Physical quantities- these 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)

Basic:

Length - 1 m - (meter)

Time - 1 s - (second)

Weight - 1 kg - (kilogram)

Derivatives:

Volume - 1 m³ - (cubic meter)

Speed ​​- 1 m/s - (meter per second)

In this expression:

number 10 - numerical value of time,

the letter “s” is an abbreviation for a unit of time (second),

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 the basic units, multiple units are used, which are 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

A phenomenon is any manifestation of something, as well as any change in the world around us. The meaning of this word is determined by the context, namely the adjective next to the term “phenomenon”. It is difficult to understand what this phenomenon is without examples, so we will give them.

• A physical phenomenon can be considered a change in the state of aggregation of a substance.
• In this area there are such unusual natural phenomena as petrified waves.
• He was frightened by something that could be called paranormal activity.

Let us take a closer look at the term “Phenomenon” depending on the context.

What is a physical phenomenon

First of all, note that a physical phenomenon is a process, not a result of something. This is the process of ongoing changes in the state or position of physical systems. Remember that a physical phenomenon is one in which the transformation of one substance into another does not occur. Its composition will remain the same, but its condition or position will change.

Physical phenomena are classified as follows:

• Electrical phenomena. They involve electric charges. For example, lightning, electric current.
• Mechanical phenomena. The movement will be relative to each other. For example, the movement of cars on the road.
• Thermal phenomena. They are associated with changes in body temperature. For example, melting snow.
• Optical phenomena. They are associated with the metamorphoses of light rays. For example, a rainbow.
• Magnetic phenomena. They arise when magnetic properties appear in an object. For example, a compass with an arrow pointing north.
• Atomic phenomena. Occur during metamorphoses in the internal structure of matter. For example, the glow of stars.

What are natural phenomena

Natural phenomena are considered to be climatic and meteorological manifestations of nature that occur naturally. Rain, snow, storm, earthquake are all examples of natural phenomena.

It is important to understand what a natural phenomenon is and how it is interconnected with physical phenomena. Thus, in one natural phenomenon one can count several physical phenomena. That is, the concept of “natural phenomenon” is broader. For example, a natural phenomenon such as a thunderstorm includes the following physical phenomena: the movement of clouds and rain (mechanical phenomena), lightning (electrical phenomenon), burning of a tree from a lightning strike (thermal phenomenon).

What is paranormal activity

When they talk about a paranormal phenomenon, they mean any changes in the surrounding reality that are not the norm, an ordinary phenomenon. They have no scientific explanation or evidence. Their existence goes beyond the understanding of the usual picture of the world. Examples of paranormal phenomena are: crying icons, the biofield of living beings.

Man lives in the natural world. You yourself and everything that surrounds you - the air, trees, river, sun - are different natural objects. Changes constantly occur with natural objects, which are called natural phenomena.
Since ancient times, people have tried to understand: how and why various phenomena occur? How do birds fly and why don't they fall? How can a tree float on water and why does it not sink? Some natural phenomena - thunder and lightning, solar and lunar eclipses - frightened people until scientists figured out how and why they occur.
By observing and studying phenomena occurring in nature, people have found application for them in their lives. Observing the flight of birds (Fig. 1), people designed an airplane (Fig. 2).

Rice. 1	Rice. 2

Watching a floating tree, man learned to build ships and conquered the seas and oceans. Having studied the method of movement of the jellyfish (Fig. 3), scientists came up with a rocket engine (Fig. 4). By observing lightning, scientists discovered electricity, without which people today cannot live and work. All kinds of household electrical devices(lighting lamps, televisions, vacuum cleaners) surround us everywhere. Various electric tools (electric drill, electric saw, sewing machine) are used in school workshops and in production.

Scientists divided all physical phenomena into groups (Fig. 6):

Rice. 6

Mechanical phenomena- these 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 swing of a pendulum).
Electrical phenomena- these are phenomena that arise during the appearance, existence, movement and interaction of electrical charges (electric current, lightning).
Magnetic phenomena- these are phenomena associated with the emergence of magnetic properties in physical bodies (attraction of iron objects by a magnet, turning the compass needle to the north).
Optical phenomena- these are phenomena that arise during the propagation, refraction and reflection of light (reflection of light from a mirror, mirages, the appearance of shadows).
Thermal phenomena- these are phenomena associated with heating and cooling of physical bodies (boiling a kettle, the formation of fog, the transformation of water into ice).
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).
Observe and explain. 1. Give an example natural phenomenon. 2. To which group of physical phenomena does it belong? Why? 3. Name the physical bodies that participated in physical phenomena.

We often take for granted everything that happens to us on earth, but every minute our lives are controlled by many forces. There are a surprising number of unusual, paradoxical, or challenging physical laws that we encounter every day. In a fun exploration of physical phenomena everyone should know, we'll talk about frequent cases that many people consider a mystery, strange forces that we cannot understand, and how science fiction can become reality through the manipulation of light.

10. Cold wind effect

Our perception of temperature is quite subjective. Humidity, individual physiology, and even our mood can change our perception of hot and cold temperatures. The same thing happens with the wind: the temperature we feel is not real. The air that directly surrounds the human body serves as a kind of air cloak. This insulating air cushion keeps you warm. When the wind blows on you, this air cushion is blown away and you begin to feel the real temperature, which is much colder. The cool wind effect only affects those objects that produce heat.

9. The faster you go, the stronger force blow.

People tend to think linearly, mostly based on observational principles; if one raindrop weighs 50 milligrams, two raindrops should weigh about 100 milligrams. However, the forces that control the universe often show us a different result due to the distribution of forces. An object moving at 40 kilometers per hour will hit a wall with a certain force. If you double the speed of an object to 80 kilometers per hour, the impact force will increase not two, but four times. This law explains why accidents on highways are much more destructive than accidents in cities.

8. Orbit is just a constant free fall.

Satellites emerge as a notable recent application to the stars, but we rarely think about the concept of "orbit." We know in general that objects move around planets or large celestial bodies and never fall. But the reason for the appearance of orbits is surprisingly paradoxical. If you drop an object, it falls to the surface. However, if it is high enough and moving at a fast enough speed, it will deflect off the ground in an arc. The same effect prevents the earth from colliding with the sun.

7. Heat causes freezing.

Water is the most important liquid on earth. This is the most mysterious and paradoxical connection in nature. One of the little-known properties of water is, for example, that warm water freezes faster than cold. It is not yet fully understood how this happens, but this phenomenon, known as the Mpemba paradox, was discovered by Aristotle about 3,000 years ago. But why exactly this happens remains a mystery.

6. Air pressure.

IN this moment you are exposed to air pressure equal to approximately 1000 kilograms, the same as a small car weighs. This is due to the fact that the atmosphere itself is quite heavy, and a person located at the bottom of the ocean experiences a pressure of 2.3 kg per square centimeter. Our body can withstand such pressure, and it cannot crush us. However, sealed objects, such as plastic bottles thrown away from very high altitude return to the ground in a compressed state.

5. Metallic hydrogen.

Hydrogen is the first element in periodic table, making it the simplest element in the Universe. Its atomic number 1 means it has 1 proton, 1 electron and no neutrons. Although hydrogen is known as a gas, it can exhibit some properties that are more common to metals than to gases. Hydrogen is located in periodic table just above sodium, a volatile metal that is part of the composition of table salt. Physicists have long understood that hydrogen behaves like a metal under high pressure, like the one found on stars and in the cores of gas giant planets. Trying to make such a compound on earth requires a lot of effort, but some scientists believe they have already created small samples by applying pressure to diamond crystals.

4. Coriolis effect.

Thanks pretty large size planet, a person does not feel its movement. However, the clockwise motion of the Earth causes objects traveling in the northern hemisphere to move slightly clockwise as well. This phenomenon is known as the Coriolis effect. Since the Earth's surface moves at a certain speed relative to the atmosphere, the difference between the rotation of the Earth and the movement of the atmosphere causes an object moving north to pick up the energy of the Earth's rotation and begin to veer east. The opposite phenomenon is observed in the southern hemisphere. As a result, navigation systems must take into account the Coriolis force to avoid heading off course.

3. Doppler effect.

Sound may be an independent phenomenon, but the perception of sound waves depends on speed. Austrian physicist Christian Doppler discovered that when a moving object, such as a siren, emits sound waves, they accumulate in front of the object and dissipate behind it. This phenomenon, known as the Doppler effect, causes the sound of an approaching object to become a pitch higher due to the shortening of the sound wavelengths. After the object passes by, the trailing sound waves lengthen and, accordingly, become tones lower.

2. Evaporation.

It would be logical to assume that chemicals must pass through a liquid state in the process of transitioning from a solid to a gaseous state. However, water can immediately transform from a solid to a gas when certain circumstances. Sublimation, or evaporation, can cause glaciers to disappear when the sun turns the ice into steam. In the same way, metals, such as arsenic, can turn into a gas when heated, releasing toxic gases. Water can evaporate below its melting point when exposed to a heat source.

1. Disguised devices.

Fast emerging technology turns science fiction stories into scientific facts. We can see objects when light of different wavelengths is reflected from them. Scientists have theorized that objects can be considered invisible when exposed to certain light. If the light around an object can be scattered, it becomes invisible to the human eye. IN Lately this theory became a reality when scientists invented a transparent hexagonal prism that scattered light around an object placed inside. When placed in an aquarium, the prism made goldfish, which floated there, invisible, and on the ground livestock disappeared from sight. This secrecy effect works on the same principles as aircrafts, which cannot be detected by radar.

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