Mechanical physical phenomena in nature are examples. Physics is the science of nature. Physical bodies and physical phenomena
We are surrounded by an infinitely diverse world of substances and phenomena.
Changes are constantly taking place in it.
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 flash of lightning during a thunderstorm, and so on - all these are natural phenomena.
Physical phenomena
Let us remember that bodies are made of substances. Note that during some phenomena the substances of bodies do not change, but during others they do. For example, if you tear a piece of paper in half, then, despite the changes that have occurred, the paper will remain paper. If you burn the paper, it will turn into ash and smoke.
Phenomena in which the size, shape of bodies, the state of substances may change, but substances remain the same, do not transform into others, are called physical phenomena(evaporation of water, glow of a light bulb, sound of strings musical instrument etc.).
Physical phenomena are extremely diverse. Among them there are mechanical, thermal, electrical, light 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 the above 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 Greek “mechane” means machine, weapon).
Many phenomena are caused by alternating heat and cold. In this case, changes occur in the properties of the bodies themselves. 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, and water into ice. Phenomena associated with heating and cooling of bodies are called thermal(Fig. 35).
Rice. 35. Physical phenomenon: transition of a substance from one state to another. If you freeze drops of water, ice will form again
Let's consider electric phenomena. The word "electricity" comes from the Greek word "electron" - amber. Remember that when you quickly take off your wool sweater, you hear a slight cracking noise. 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 small pieces of paper and place them on the table surface. Comb clean and dry hair with a plastic comb and hold 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 are all electrical phenomena. The operation of the telephone, radio, television, and various household appliances are examples of human use of electrical phenomena.
Phenomena that are associated with light are called light phenomena. Light is emitted by the Sun, stars, lamps and some living creatures, such as fireflies. Such bodies are called glowing.
We see under the condition of exposure to light on the retina of the eye. In absolute darkness we cannot see. 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 talk about as a night luminary, is in fact only a kind of reflector of sunlight.
By studying the physical phenomena of nature, man learned to use them in everyday life.
1. What are called natural phenomena?
2. Read the text. List what natural phenomena are named in it: “Spring has come. The sun is getting hotter and hotter. The snow is melting, streams are flowing. The buds on the trees have swelled and the rooks have arrived.”
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 - electric; in the fourth – light phenomena.
Physical phenomena: flash of lightning; snow melting; coast; melting metals; operation of an electric bell; rainbow in the sky; sunny bunny; moving stones, sand with water; boiling water.
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Many things are incomprehensible to us not because our concepts are weak; but because these things are not included in the range of our concepts. Kozma Prutkov.
Auroras
Since ancient times, people have admired the majestic picture of the auroras and wondered about their origin. One of the earliest mentions of auroras is found in Aristotle. In his “Meteorology”, written 2300 years ago, you can read: “Sometimes on clear nights many phenomena are observed in the sky - gaps, gaps, blood-red color...
It looks like there's a fire burning."
Why does a clear beam ripple at night?
What thin flame spreads into the firmament?
Like lightning without threatening clouds
Striving from the ground to the zenith?
How can it be that a frozen ball
Was there a fire in the middle of winter?
Lomonosov M.V.
What is the aurora? How is it formed?
Answer. Polar Lights- this is a luminescent glow resulting from the interaction of charged particles (electrons and protons) flying from the Sun with atoms and molecules earth's atmosphere. The appearance of these charged particles in certain regions of the atmosphere and at certain altitudes is the result of the interaction of the solar wind with magnetic field Earth.
How is a rainbow formed?
Why do you sometimes see a side rainbow?
How far from us does a rainbow form?
AnswerRainbows are usually explained by the simple refraction and reflection of the sun's rays in raindrops. Light emerges from the droplet at a wide range of angles, but the greatest intensity is observed at the angle corresponding to the rainbow. Visible light Different wavelengths are refracted differently in a drop, that is, depending on the wavelength of light (that is, color). A side rainbow is formed by the reflection of light twice inside each drop. In this case, the light rays exit the drop at different angles than those that produce the main rainbow, and the colors in the secondary rainbow are in reverse order. The distance between the drops that cause the rainbow and the observer does not matter.
Why does a rainbow have an arc shape?
Answer. A rainbow occurs due to the dispersion of sunlight in water droplets. In each droplet the beam experiences multiple internal reflection, but with each reflection some of the energy comes out. Therefore, the more internal reflections the rays experience in a drop, the weaker the rainbow. You can observe a rainbow if the Sun is behind the observer. Therefore, the brightest, primary rainbow is formed from rays that have experienced one internal reflection. They intersect the incident rays at an angle of about 42°. The geometric locus of points located at an angle of 42° to the incident ray is a cone, perceived by the eye at its apex as a circle. When illuminated with white light, a stripe of color will be produced, with the red arc always higher than the violet arc.
Mirages
Imagine a scorching desert; All around, wherever you look, there is hot sand. And suddenly a lake appears ahead, somewhere near the horizon. It looks absolutely real. It seems that you only need to cover one or two kilometers and you can freshen up. Even the splash of water appears in the imagination. But now you walk one, and two, and three kilometers, and the lake is still somewhere ahead, and there are still only sands around.
K.D. Balmont "Oasis".
Oh, how far you are! I can't find you
can not found!
Tired eyes from the vastness of the desert
deserted.
Only camel bones turn white
on a dim path
Yes, stunted grasses snake over the soil
meager.
I'm waiting and yearning. Gardens grow in the distance.
Oh joy! I see palm trees growing
turning green.
The jugs sparkle, ringing from the brilliant
water.
Getting closer, getting brighter! - And the heart
began to beat, timid.
He is afraid and whispers: “Oasis!” - How sweet
blossom
In the gardens, where the holiday is captivating
life is young!
But what is it? Camel bones lie
on a way!
Everything was hidden. Only the wind rushes,
sweeping the sands.
What causes the “oasis” mirage in the desert?
Answer.Rays of light coming from the blue sky are refracted in the surface layer of air, in which the temperature decreases with height. The rays are deflected towards the observer, and he, perceiving the rays as straight, sees the blue surface of the water at some distance ahead. Image jitter caused by fluctuations in the refractive index of hot air creates the illusion of flow or ripples in water.
Tsunami
Tsunami is a Japanese term meaning an unusually large wave. Tsunami waves are caused by the sudden displacement of large areas of the ocean floor during underwater earthquakes. They, as a rule, form a group of 2-3 waves, which are almost invisible in the open sea, since they are very long (length up to 100 kilometers) and flat (height up to 1 meter) and therefore not dangerous. When approaching the shore, due to braking on the bottom, the length decreases, and the height, naturally, increases (as with any waves running, say, onto a beach) and can reach 30 meters (according to eyewitnesses). Moving at enormous speeds, up to 800 kilometers per hour (this is the speed of a modern aircraft), and suddenly falling on coastal areas, they cause huge destruction, and sometimes human casualties.
Ball lightning
Ball lightning is a luminous spheroid with a diameter of 10-20 cm or more, weighing about 5-7 grams. For the most part ball lightning have the shape of a ball. It is energetically more profitable for them to exist in this form. But there are pear-shaped and drop-shaped ball lightning, and also very rarely others unusual shapes, some of which can easily be mistaken for UFOs. Color - white, yellow, red or orange. Light emission is approximately the same as from a 100 W light bulb.Exists from one second to several minutes. It moves at a speed of no more than 10 m/s, and sometimes rotates. Ball lightning moves along invisible fields that follow the terrain. Being a material and electrically charged object, ball lightning is influenced by both the gravitational and electric fields of the Earth, which greatly increases before and during a thunderstorm. Around the surface of the Earth there are so-called equipotential surfaces invisible to us, characterized by a constant value of the electric potential. These surfaces follow the terrain. They go around buildings and treetops. Being a light freely wandering charge, ball lightning can “sit” on any equipotential surface and slide along it without expending energy. From the outside, it will seem that it hovers above the surface of the Earth and moves along it, repeating the terrain. To get into a closed room, ball lightning takes the form of a thread.
Physical bodies are " actors» physical phenomena. Let's get to know some of them.
Mechanical phenomena
Mechanical phenomena are the movement of bodies (Fig. 1.3) and their action on each other, for example repulsion or attraction. The action of bodies on each other is called interaction.
We will get to know mechanical phenomena in more detail this academic year.
Rice. 1.3. Examples of mechanical phenomena: movement and interaction of bodies during sports competitions (a, b. c); movement of the Earth around the Sun and its rotation around its own axis (r)
Sound phenomena
Sound phenomena, as the name suggests, are phenomena involving sound. These include, for example, the propagation of sound in air or water, as well as the reflection of sound from various obstacles - say, mountains or buildings. When sound is reflected, a familiar echo appears.
Thermal phenomena
Thermal phenomena are the heating and cooling of bodies, as well as, for example, evaporation (the transformation of a liquid into steam) and melting (the transformation of a solid into a liquid).
Thermal phenomena are extremely widespread: for example, they determine the water cycle in nature (Fig. 1.4).
Rice. 1.4. Water cycle in nature
Heated sun rays the water of the oceans and seas evaporates. As the steam rises, it cools, turning into water droplets or ice crystals. They form clouds from which water returns to Earth in the form of rain or snow.
The real “laboratory” of thermal phenomena is the kitchen: whether soup is being cooked on the stove, whether water is boiling in a kettle, whether food is frozen in the refrigerator - all these are examples of thermal phenomena.
The operation of a car engine is also determined by thermal phenomena: when gasoline burns, a very hot gas is formed, which pushes the piston (motor part). And the movement of the piston is transmitted through special mechanisms to the wheels of the car.
Electrical and magnetic phenomena
The most striking (in the literal sense of the word) example of an electrical phenomenon is lightning (Fig. 1.5, a). Electric lighting and electric transport (Fig. 1.5, b) became possible thanks to the use of electrical phenomena. Examples of magnetic phenomena are the attraction of iron and steel objects by permanent magnets, as well as the interaction of permanent magnets.
Rice. 1.5. Electrical and magnetic phenomena and their uses
The compass needle (Fig. 1.5, c) rotates so that its “north” end points north precisely because the needle is a small permanent magnet, and the Earth is a huge magnet. The Northern Lights (Fig. 1.5, d) are caused by the fact that electrically charged particles flying from space interact with the Earth as with a magnet. Electrical and magnetic phenomena the operation of televisions and computers is determined (Fig. 1.5, e, f).
Optical phenomena
Wherever we look, we will see optical phenomena everywhere (Fig. 1.6). These are phenomena associated with light.
An example of an optical phenomenon is the reflection of light various items. Rays of light reflected by objects enter our eyes, thanks to which we see these objects.
Rice. 1.6. Examples of optical phenomena: The sun emits light (a); The moon reflects sunlight (b); Mirrors (c) reflect light especially well; one of the most beautiful optical phenomena - rainbow (d)
As you know, phenomena are changes that occur in natural bodies. Various phenomena are observed in nature. The sun is shining, fog is forming, the wind is blowing, horses are running, a plant sprouts from a seed - these are just some examples. Everyday life Each person’s life is also filled with phenomena that occur with the participation of man-made bodies, for example, a car is driving, an iron is heating up, music is playing. Look around, and you will see and be able to give examples of many other phenomena.
Scientists divided them into groups. Distinguish biological, physical, chemical phenomena.
Biological phenomena. All phenomena that occur with bodies of living nature, i.e. organisms are called biological phenomena. These include seed germination, flowering, fruit formation, leaf fall, animal hibernation, and bird flight (Fig. 29).
Physical phenomena. Signs of physical phenomena include changes in shape, size, location of bodies and their state of aggregation(Fig. 30). When a potter makes a product from clay, the shape changes. When mining coal the sizes of rock pieces change. While the cyclist is moving, the placement of the cyclist and the bicycle relative to the bodies located along the road changes. Melting of snow, evaporation and freezing of water are accompanied by the transition of matter from one state of aggregation to another. During a thunderstorm, thunder rumbles and lightning appears. These are physical phenomena.
Agree that these examples of physical phenomena are very different. But no matter how diverse the physical phenomena are, the formation of new substances does not occur in any of them.
Physical phenomena - phenomena during which new substances are not formed, but the size, shape, placement, and state of aggregation of bodies and substances change.
Chemical phenomena. You are well aware of such phenomena as the burning of a candle, the formation of rust on an iron chain, the souring of milk, etc. (Fig. 31). These are examples of chemical phenomena. Material from the site
Chemical phenomena - these are phenomena during which other substances are formed from one substance.
Chemical phenomena have a wide range of applications. With their help, people mine metals, create personal hygiene products, materials, medicines, and prepare a variety of dishes.
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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).
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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 power tools (electric drill, power saw, sewing machine) are used in school workshops and in production.
Scientists divided all physical phenomena into groups (Fig. 6):
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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 electric charges ( electricity, lightning).
Magnetic phenomena- these are phenomena associated with the emergence of physical bodies magnetic properties(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 of a natural phenomenon. 2. To which group of physical phenomena does it belong? Why? 3. Name the physical bodies that participated in physical phenomena.
