Since ancient times, people have been collecting information about the world in which they live. There was only one science that unites all the information about nature that mankind has accumulated at that time. Then people did not yet know that they were observing examples of physical phenomena. At present, this science is called "natural science".
What physical science studies
Over time, scientific ideas about the world around them have changed markedly - there are much more of them. Natural science has split into many separate sciences, including biology, chemistry, astronomy, geography, and others. Physics is not the last in a number of these sciences. Discoveries and achievements in this area have allowed humanity to possess new knowledge. These include the structure and behavior of various objects of all sizes (from giant stars to the smallest particles - atoms and molecules).
The physical body is ...
There is a special term "matter", which in the circles of scientists is called everything that is around us. A physical body consisting of matter is any substance that occupies a certain place in space. Any physical body in action can be called an example of a physical phenomenon. Based on this definition, we can say that any object is a physical body. Examples of physical bodies: button, notebook, chandelier, cornice, moon, boy, clouds.
What is a physical phenomenon
Any matter is in constant flux. Some bodies move, others touch the third, the fourth rotate. It is not for nothing that many years ago the philosopher Heraclitus uttered the phrase "Everything flows, everything changes." Scientists even have a special term for such changes - these are all phenomena.
Everything that moves belongs to physical phenomena.
What are the types of physical phenomena
- Thermal.
These are phenomena when, due to the influence of temperature, some bodies begin to transform (shape, size and state change). An example of physical phenomena: under the influence of the warm spring sun, icicles melt and turn into liquid, with the onset of cold weather, the puddles freeze, boiling water becomes vapor.
- Mechanical.
These phenomena characterize a change in the position of one body in relation to the rest. Examples: the clock is running, the ball is jumping, the tree is swinging, the pen is writing, the water is flowing. They are all in motion.
- Electrical.
The nature of these phenomena fully justifies its name. The word "electricity" has its roots in the Greek language, where "electron" means "amber". The example is quite simple and probably familiar to many. When you suddenly take off your woolen sweater, you can hear a slight crackling sound. If you do this by turning off the light in the room, then you can see sparks.
- Light.
The body participating in the phenomenon associated with light is called luminous. As an example of physical phenomena, we can cite the well-known star of our solar system - the Sun, as well as any other star, lamp, and even a firefly bug.
- Sound.
The propagation of sound, the behavior of sound waves in collisions with an obstacle, as well as other phenomena that are somehow related to sound, belong to this type of physical phenomenon.
- Optical.
They are due to light. So, for example, man and animals are able to see, because there is light. This group also includes the phenomena of propagation and refraction of light, its reflection from objects and passage through different media.
Now you know what physical phenomena are. However, it should be understood that there is a certain difference between natural and physical phenomena. Thus, in a natural phenomenon, several physical phenomena occur simultaneously. For example, when lightning strikes the ground, the following sound, electrical, heat and light occur.
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 is known from biology, constantly goes through any stages of development. Grinding grains into flour, falling stones, boiling water, lightning, glow of a light bulb, dissolving sugar in tea, movement of vehicles, lightning, rainbows are examples of physical phenomena.
And with substances (iron, water, air, salt, etc.), various changes or phenomena occur. The substance can be crystallized, melted, crushed, dissolved and re-isolated from solution. However, its composition will remain the same.
So, granulated sugar can be crushed into a powder so fine that from 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 you evaporate water from the sugar solution, the sugar molecules will again combine with each other into crystals. But even when dissolved in water, and when grinding, sugar remains sugar.
In nature, water forms rivers and seas, clouds and glaciers. When evaporated, the water turns into steam. Water vapor is water in a gaseous state. When exposed to low temperatures (below 0˚C), water turns into a solid state - it turns into ice. The smallest particle of water is a water molecule. A 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 to another.
When characterizing this or that substance as a gas, liquid or solid, they mean the state of the substance under ordinary conditions. Any metal can be not only melted (converted into a liquid state), but also converted into 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˚С. And, for example, carbon dioxide can be converted into "dry ice" by cooling.
Phenomena in which there is no transformation of some substances into others are referred to as physical phenomena. Physical phenomena can lead to a change, for example, the state of aggregation or temperature, but the composition of the substances remains 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 occur when electric charges appear, exist, move and interact (electric current, telegraphy, lightning during a thunderstorm).
Magnetic phenomena are phenomena associated with the appearance of magnetic properties in physical bodies (the attraction of iron objects by a magnet, the rotation of the compass needle to the north).
Optical phenomena 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 arise when the internal structure of the substance of physical bodies changes (the glow of the Sun and stars, an atomic explosion).
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Lesson number 1.Physics studies the world in which we live, the phenomena occurring in it, reveals the laws that govern these phenomena, and how they are interconnected. Among the wide variety of phenomena in nature, physical phenomena occupy a special place. These include:
Mechanical phenomena(for example, the movement of cars, airplanes, celestial bodies, fluid flow).
Electrical phenomena(for example, electric current, heating of conductors with current, electrification of bodies).
Magnetic phenomena(for example, the effect of magnets on iron, the effect of the earth's magnetic field on the compass needle).
Optical phenomena(for example, reflection of light from mirrors, emission of light rays from various light sources).
Thermal phenomena(melting ice, boiling water, thermal expansion of bodies).
Atomic phenomena(for example, the operation of atomic reactors, the decay of nuclei, the processes taking place inside the stars).
Acoustic phenomena(e.g. echo).
Exercise
Give examples of physical phenomena: mechanical, electrical, magnetic, optical, thermal.
Which of the following are physical phenomena?
Force
Ton
Snow melting
Molecule
Boiling
Time
Walking
Lesson number 2.
Any science uses its own special words - scientific terms. A physicist, speaking about the motion of bodies, usually does not take into account what exactly moves, since for the study of mechanical motion this is insignificant in many problems. Therefore, in these cases, they speak of the physical body.
Physical body - these are all objects that surround us (for example, a car, table, mug, doll, etc.)
Any material object (physical body) consists of matter, and we can see and touch it.
Substance- this is what all the objects around us are made of (for example, the physical body-mug, consists of porcelain, porcelain is a substance; the physical body is a spoon, consists of aluminum, aluminum is a substance).
Exercise.
Give examples of 10 physical bodies and substances of which they are composed.
Lesson number 3
When conducting experiments, we are dealing with physical parameters that can either change over time or not. The characteristics of bodies or processes that can be changed are called physical quantities.
Physical quantities include volume, mass, length, time, speed, temperature, weight, area, etc.
Any physical quantity is measured in its own units. Usually all physical quantities are measured in the international system of units.
For example, the unit of time is the second (1s), the unit of length is the meter (1m).
To measure physical quantities, use measuring instruments. The simplest measuring instruments are a thermometer, stopwatch, ruler, etc.
Exercise.
1.Reduce riddles about physical devices:
Two sisters swayed
The truth was sought.
And when they achieved
Then they stopped.
There's a plate on the wall
An arrow walks on the plate.
This forward arrow
He knows the weather for us.
Eremushka has been walking all century,
No sleep for him, no nap.
He keeps track of the steps,
And still it will not leave the place.
2The physical quantities and their units are listed below. Choose the correct match.
Length, second
Time, meter
Volume, cubic meter
Temperature, millimeter
Express 1.5m in mm, cm, dm.
Lesson number 4
Physical dictation.
Arrange the words: detail, water, mass, cylinder, thermometer, piece of ice, volume, time, mercury, beaker, water vapor, tape measure, height, clouds of steam, ice - in four columns of the table:
|
Physical body |
substance |
Physical quantity |
appliance |
Physical bodies are the "actors" of physical phenomena. Let's get acquainted with 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 acquainted with 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); the 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 associated with sound. These include, for example, the propagation of sound in air or water, as well as the reflection of sound from various obstacles, such as mountains or buildings. When sound is reflected, an echo familiar to many arises.
Thermal phenomena
Thermal phenomena are the heating and cooling of bodies, as well as, for example, evaporation (the transformation of a liquid into vapor) and melting (the transformation of a solid into a liquid).
Thermal phenomena are extremely widespread: for example, they cause the water cycle in nature (Fig. 1.4).
Rice. 1.4. The water cycle in nature
Warmed by the sun's rays, the water of the oceans and seas evaporates. As the steam rises, it cools down, 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 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 caused by thermal phenomena: when gasoline burns, a very hot gas is formed, which pushes the piston (engine 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 due to the use of electrical phenomena. Examples of magnetic phenomena are the attraction of iron and steel objects by permanent magnets, and the interaction of permanent magnets.
Rice. 1.5. Electrical and magnetic phenomena and their uses
The compass needle (Fig. 1.5, c) turns so that its "north" end points to the north precisely because the arrow 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 cause the operation of televisions and computers (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 by various objects. The rays of light reflected by objects fall into our eyes, due to which we see these objects.
Rice. 1.6. Examples of optical phenomena: The sun emits light (s); The moon reflects sunlight (b); mirrors reflect light especially well (c); one of the most beautiful optical phenomena - rainbow (g)
Over the centuries and millennia, mankind has been faced with many to explain that it was not always able to. Changes in the weather, the movement of heavenly bodies, the growth of plants, the light of a flame, the change of seasons - all these processes for our ancestors seemed like mysterious mysteries of nature. Gradually, humanity came to an explanation of the material nature of many of them: some - earlier, others - relatively recently. Whole branches of science arose that investigated certain natural phenomena.
What did our ancestors observe most often? Change of day and night, cold and heat, the movement of clouds and sun across the sky, rain and thunderstorms, wind blowing, grain germination through the soil, water freezing and ice melting. Most of the observed ones were mechanical phenomena, that is, associated with the movement and displacement of various bodies, both living and non-living. These include both the growth of grass and the movement of the moon across the sky.
Mechanical phenomena, examples of which are found everywhere, along with many others, have been studied by mankind over the centuries. The initial knowledge of mankind about the world around them has grown over time into a harmonious system. Whole branches of science have appeared, specializing in the study of certain processes. Physics studies mechanical phenomena, more precisely, its section called kinematics - the science of motion and displacement of bodies. The modern concepts of kinematics are based on the postulates of classical Newtonian mechanics. They are based on a mechanistic concept of the structure of the world around us, which prevailed in science until the beginning of the twentieth century. These ideas are completely correct and justified in terms of movements occurring at relatively low speeds (we are not talking about objects, the size of which is much less than the distance traveled by them.
In general, mechanical phenomena are a kind of group of physical phenomena. Physical phenomena include those in which there is no transformation of one substance into another. In this case, it can change (water turns into ice), but this is one and the same substance. The phenomena of interactions of different substances with the subsequent formation of new ones are studied by another science - chemistry.
Mechanical phenomena are not the only ones in physics. In addition to them, physics studies what happens during the emergence, movement, interaction of electric charges (electric current, lightning, telegraph), magnetic (attraction of metal objects by a magnet, rotation of the compass needle to the north), optical, occurring during reflection and refraction of light (mirages, rainbows, reflection objects in the mirror and casting a shadow with it), as well as thermal (melting snow, fog, boiling water) and
Of course, mechanical phenomena are among the most studied. The science that studies them - mechanics - sets as its main task the determination of the location of the body in the surrounding space at any arbitrary moment in time. The movement of a body in mechanics is considered not by itself, but in relation to other bodies, one of them can be taken as the initial one when counting. The movement is considered in a coordinate system along three mutually perpendicular axes having a common reference point.
It is also taken into account that the body can move relative to some bodies and not move relative to others. There are concepts of displacement and the path traversed by bodies. Thus, mechanics, which studies the movement of bodies, considers its main task to be finding the position of the body at any moment.
Of great importance in the study of mechanical phenomena are the concepts of speed and time, which are necessary to determine the distance traveled. The science of the motion of bodies also considers different ones - translational, rotational, mixed.
Physics as a science that studies an infinite variety of natural phenomena (mechanical and not only), of course, is one of the most interesting and fascinating branches of knowledge.
