Lesson about the world around us. 4th grade. 11/26/2014
Teacher: Makarova E.V. MOAU Secondary School No. 16.
Topic: How a person uses the properties of air.
Lesson type: Discovery of new knowledge.
Goals and objectives :
Educational:
To form a concept about air: its composition and properties;
Consider examples of the use of human air.
. Metasubject:
Develop the ability to observe, conduct experiments,observe the progress and results of the experiment;conclusions and conclusions;
- develop interest in the subject;
Create conditions for expressing reasoned opinions;
Develop mental operations: synthesis, analysis, generalization;
summarize the received information in the form of a cluster;
Develop communication skills and a culture of command.
Personal:
Develop cooperation skills through organizing work in pairs and groups;
Cultivate a positive attitude towards learning activities and self-confidence.
- cultivate the need to improve your oral and written speech
Leading activity: productive
Working methods: activity method, partially - search, verbal, visual, practical (experiments)
Forms of work: frontal, group (children are seated in groups), independent.
Teacher function: organizer of cooperation, consultant managing experimental search work.
Pedagogical technologies:
Activity-based teaching method;
Explanatory and illustrative teaching;
Pedagogy of cooperation (educational dialogue, educational discussion);
ICT - technology (presentation).
Material for the lesson: Textbook “The world around us. Human and nature. 4th grade." A.A.Vakhrushev
Equipment:
1. Presentation for the lesson
2. Fan, jar and glass of water, syringe, empty bag, balls.
During the classes
1. Organizational moment. Motivation for learning activities. (5 minutes)
Checking homework.
We welcome all guests. You can watch a lesson about the world around you.
The more active and organized we work, the more interesting things I can show and tell you. Want to know more? Then let's work!
What has existed for millions of years, is the basis of life on earth, is used by humans and has not yet ended? (water)
Let's remember the properties of water and how people use them. (Front):
What is the name of the water layer of the earth?
What role does water play in the life of living organisms?
Name the main properties of water.
Formulate the law of communicating vessels. Where did people learn to use it?
Why does a nut dipped in water stretch the rubber band less than a nut suspended in the air?
Where does a person use the buoyant property of water?
What property of water is used in washing?
What happens to a tin can if you heat it without opening it?
What property of water is used in a steam engine?
Name the three states of water. Give examples of them in nature.
Individually on cards:
Use arrows to connect the properties of water and how to use them.
Fluidity Steam Engine
Has buoyant force Sweetening food
Property of communicating vessels Water wheel, power plant turbine
Expands when heated Invention of ships
Solvent Water Pipe
2. Updating knowledge, fixing difficulties, setting lesson goals.
Building a project to get out of a problem (3 minutes)
What else has existed for millions of years, been used by humans and has not yet ended? (air)
Try to formulate the topic of today's lesson from my question and the previous topic.
Subject: How a person uses air and the properties of air.
Actually, today’s topic is the main question that we have to answer. Can you immediately give a complete, detailed answer?
What will be the objectives of the lesson?
Lesson objectives: 1) Find out (repeat) what air is and its use.
2) Find out (repeat) the properties of air and their use by humans.
Which one would you suggest?work plan over the topic?
1) Remember what we know
2) Experiments, observations - summary table
3) Conclusions
3. Implementation of a project to get out of a problem (7 minutes)
- Let's remember what we know:
What is the name of the air shell of the Earth? (atmosphere)
What is air? (mixture of gases)
Would life on Earth be possible without this air envelope? Why?
How do animals and plants use air? (all living organisms breathe using oxygen in the air)
How do plants eat? (plants use carbon dioxide in the air during photosynthesis to create organic matter and release oxygen)
Why can't organisms live even 5 minutes without air? (air cannot be stored for future use)
What other role does the earth's atmosphere play? (the atmosphere protects the Earth’s surface from overheating and hypothermia; thanks to the ozone layer, it protects from harmful ultraviolet rays).
What properties of air do you already know? (tasteless, colorless, odorless)
Suggest how we can verify that air exists and is not empty space? Is it still possible to feel, touch, see it? Look at the objects presented on my table (fan, container with water and an empty glass, an empty bag). Suggest how they can be used in proof.
Experience 1.
Wave a fan (notebook) in front of your face. How did you feel? (touch)
Test touch, air movement using the tools at hand that everyone has on their desk? (wave notebook)- felt
- When moving, the air is tangible.
Experience 2.
Place the glass turned upside down into a container of water.
Why doesn't water get into the glass? (there is air - an air bell)
I'll tilt the glass a little. What happened? (air in the form of bubbles came out of the glass and rose above the surface of the water)
Experience 3.
Catch air in an empty plastic bag.
So, the conclusion: air is a gas, it surrounds us...everywhere. Air does not have a constant shape and tends to fill the entire volume available to it.
Remember your first experience with a fan. What is wind? (wind is the movement of air)
Think about how a person can force the wind to help him?
(the wind inflates the sails - already 2-3 thousand years ago the Egyptians sailed the Mediterranean Sea on quite advanced sailing ships, windmills, wind engines of power plants are the cleanest way to generate electricity)
- table
Opentextbook onpage 89. The illustrations show the use of wind power by man.
Who remembers: how the wind arises? (wind moves from less warm areas to warmer ones.
Rememberyour observations how have you ever sat by the fire. What does warm air from a fire do to light ash particles? (lifts them up)
Consequently, warm air rises and moves from a less heated area to a more heated one.
Remember where batteries and vents are installed in our premises, why? (at the bottom so that warm air is evenly distributed throughout the entire room)
We talked about the behavior of warm and cold air. What property of air is this related to, what happens to air when heated and cooled?
(when heated it expands, when cooled it contracts)
Experience 2.
Observe another experiment confirming this property. Vika conducted and recorded it at home due to limited time during the lesson.
We put a ball on a plastic bottle with air inside. First, we immersed the structure in a basin of hot water. After some time, and quite a long time, the ball began to inflate. This means that the air did not fit in the bottle, it expanded when heated and began to inflate the balloon. Then we lowered our structure into a basin of cold water. Gradually, the ball began to deflate - it began to have enough space in the bottle. This means that when air cools, it compresses.
Conclusion:Air expands when heated and it becomes easier, rises. When cooled, it contracts, becomes heavier and sinks down.- table
Who can guess how else people learned to use the property of warm air to rise upward? (Balloons)- table
Remember what force pushes a log out of the water? Think about why balloons filled with hydrogen fly into the sky. What force causes objects lighter than air to rise?
(buoyant force) – table
The beginning of the era of aeronautics can be considered in 1783, when the Montgolfier brothers took to the skies in a hot air balloon. However, the main disadvantage of the balloon is its poor controllability. At the end of XIXcenturies, inventors designed aircraft that could move using a propeller driven by an engine. These were airships filled with hydrogen. They were enormous in size. For example, the airship built by the German inventor von Zeppelin was 128 m long and almost 12 m wide. But the future lay with a different type of aircraft
Experience 3.
Throw a piece of paper into the water.
Why did the leaf not remain hanging in the air, but lie on the surface of the water?
(air is a less dense substance,low density) – table
Is it possible to lean on the water? Under what conditions? Guess whether it is possible to lean on the air, under what conditions?
(increase the support area, reduce weight, develop greater speed)
But the resistance to movement in the air is minimal, so the speed of movement in the air becomes less limited.
How do you think man learned to use low air density? (airplanes, helicopters, rockets - moving long distances at high speed)
The emergence of aviation became possible when the power of engines and, at the same time, the ease of materials for construction reached a certain level. The first airplane powered by the Wright brothers took off in 1903. People have learned to use the airspace itself.
Look at the illustrations on page 90: What are these aircraft called?
Use yourslife experience , guess. How can my blouse be related to the topic of the lesson?
( air is a poor conductor of heat - low thermal conductivity) – table
Which statement do you think is correct: clothes warm the body, or clothes heat up from the body?
Due to its low density, air is a poor conductor of heat. When it’s cold, animals raise their fur, birds raise their feathers, and a person puts on a knitted blouse. Woolen items, down jackets, and fur coats create a thick air layer between the body and the external environment. which prevents the body from losing heat.Table - woolen items.
Where else does a person use the low thermal conductivity of air? (stand by the window)
(double window frames in houses, the air between them allows you to keep heat in the houses)- table
The textbook invites us to get acquainted with another property of air and
To do this, carry out the following experiment:
Experience 4. (child conducts at the blackboard)
Let's take a plastic syringe without a needle and put the piston in the middle position. Holding the hole for the needle with your finger, we will try to compress and stretch the air. Draw a conclusion.
(Conclusion: With force, air can be compressed and stretched, but it tends to maintain its original volume.)
This property is called -elasticity – table.
Where can the elasticity of pumped air be used?
(inflatable mattresses, car tires, balls) - table
So, look at the summary table of the use of air properties that we have obtained.
To this table I want to add that people have learned to use not only the properties of air, but also the gases that make up its composition.
- Look at the diagram to see what other gases, besides those mentioned today, oxygen and carbon dioxide, are included in the air.
Work in groups.
The textbook does not offer us ways to use the gases that make up the air. Try it yourself. Open your notebooks to page 35. Turn around and form groups of fours. Discuss your assumptions. Signal when ready.
Let's add to the table. How does a person use the gases that make up the air?
Nitrogen – nitrogen fertilizers
Oxygen – used for welding
Carbon dioxide is added to water to create carbonation.
Balloons are filled with hydrogen
Let's draw conclusions: what has a person learned and used about air?
(wind strength, air properties and composition)
5. Primary consolidation in external speech . Inclusion in the knowledge system.
(2 minutes)
To check how you have mastered the material, I suggest answering my questions by playing the game “What would happen on Earth if the air... was not elastic?
If air didn't move, would there be no wind?
What if there was no carbon dioxide in the air?
What if the air were denser than it is?
What if there was no oxygen in the air?
What property of air is most important for a ball? Blankets? A balloon? Airplane? Parachute?
What gas, which is part of the air, maintains combustion in the furnace and maintains our body temperature? (oxygen, when burned, energy and heat are generated that maintain the temperature of the body and the furnace)
Working in a notebook (subject to time availability)
I invite you to reflect and express your point of view:
Name objects that benefit from air density (the more, the better) -
parachute, plane, air mattress, ball, balloons
Name objects that are hindered by air density (the lower it is, the better) - sailboat, sweater, airplane, rocket
6. Independent work with verification against the standard . (3 minutes)
Work in a notebook. Page 34. No. 2
Write what properties of air are used
Helicopter
density
Double glazing
low thermal conductivity
Plant
presence of carbon dioxide in the air
Rocket
density
Air mattress
elasticity
Bonfire
presence of oxygen in the air
Check your work against the standard.
Who did it without errors?
Who had difficulties, what are your next steps? (read carefully, understand the textbook material at home)
7. Reflection on educational activities. (3 minutes)
The lesson is coming to an end. Let's summarize.
What was the purpose of today's lesson? (Find out how a person uses air)
Have you achieved your goals? Prove:
What other properties of air have people learned to use? (airspace, wind force, air components)
What properties of air do you remember?
Who is happy with the lesson and with themselves in the lesson?
Who else had problems with my questions? - work carefully at home
Who is very pleased with both the lesson and themselves?
Thank you for the lesson. Thank you for your attention.
Or a quick survey:
What is air?
What gases are included in air?
Does air have a certain shape and volume?
What is the air shell of the earth called?
What did people use in ancient times to travel on sailboats across the seas?
What does air do when heated?
Why don't planes crash? Helicopters
What property of air is used in air mattresses, balls
What gas is used in the production of soda?
How long can a person live without air?
There is a lot of air on earth, there is enough for everyone, there is no need to worry about it
Experiment 6. Air has weight, mass.
I'll take 2 identical balls. One of the balloons is inflated with air, the other is not. Both balls are tied to the ends of the sticks. I will place the stick with the uninflated balloon on the edge of the table so that it is in balance. I will mark the intersection with the table. I’ll put a stick with an inflated balloon in the same way. What happened? (the inflated balloon with air outweighed)
- Therefore?...(air has weight, mass)
- If air has weight, it means it presses on the Earth.
- The wind blows from an area of high pressure to an area of low pressure (if you are under pressure, you want to run away, go to an area of less strong pressure). An area of high pressure is usually found in areas with cold air masses, and low pressure in areas with warm air masses.
Personal:
conscious
attitude
to teaching
Cognitive:
Comparison
Synthesis
Structured
knowledge
Nomination
hypotheses
Cognition:
Staging
Problems
Nomination
hypotheses
Regulatory:
Goal setting
Planning
Significant
symbolic
modeling
Cognitive:
Structured
knowledge
Nomination
hypotheses
Cognitive:
Structured
knowledge
Regulatory:
Control
Grade
Correction
Strong-willed
self-regulation
Communication-
tive:
To express
your thoughts
in partnership
Regulatory:
Strong-willed
self-regulation
Self-esteem
Cognitive:
Reflection
educational
process
Regulatory:
Strong-willed
Self-regulation
Control,
Self-esteem
Cognitive:
Reflection
educational
process
We have provided basic information about air, and in this article we introduce you to the main ways of using it - although most of them are familiar to you, we thought it was important to summarize this information. You will also learn several interesting facts about air - for example, where is it the cleanest in the world and how much of it does a person need per day.
Air is a necessary medium for breathing of all living organisms on Earth. With it, all living cells receive oxygen. In turn, it provides oxidation processes that supply the body with the necessary energy. In addition, it finds wide application in a wide variety of fields.
Main ways of using air:
In the chemical industry, inert gases are extracted from the air, and acids and oxides are synthesized with the help of air.
In the petrochemical industry, all pipelines are purged with air before the first start-up.
In industrial production it is used to increase the temperature of technological processes.
All processes and mechanisms associated with fuel combustion are based on air consumption. Air is necessary to generate heat for the operation of internal combustion engines.
In the food industry, air is needed to ensure the processes of fermentation, fermentation, etc.
In laboratories, dry-air sterilization of glassware, instruments and equipment is used.
The paint and varnish industry uses accelerated drying using compressed air.
Air under pressure is pumped into automobile and other types of tires.
Using compressed air, they wash cars, clean equipment, premises, and clothing from dust and shavings in woodworking; clean the instrument.
Compressed air is used in jackhammers, pneumatic construction guns, screwdrivers and impact wrenches, pneumatic drills, and spray guns; in air guns.
Compressed air is used in dentistry, for purging equipment for various purposes (pipelines, boiler rooms, computers, etc.).
- Only one-fifth of the air consists of oxygen, which we need for life, and it may seem that it would be better if there was less nitrogen in it and more useful oxygen. This is wrong. The main biological role of nitrogen in the air is to act as an oxygen diluent. In pure oxygen, life is impossible under normal conditions. Breathing pure oxygen above 93% at normal pressure is fatal.
After scientists realized that air is not an ephemeral entity, but a material mixture of gases with certain physical properties, it became clear that it is the movement of air masses that is responsible for the weather and various natural phenomena: winds, cyclones, tornadoes, tornadoes, trade winds, thunderstorms, snowfalls, etc. We can assume that meteorology, the science of weather, began its history then.
It is believed that the cleanest air is on the island of Tasmania.
At great depths and at high altitudes, the air affects a person differently than at approximately sea level. At depth, with increased pressure, nitrogen in the air mixture begins to have a narcotic effect, causing a feeling of euphoria, inappropriate behavior, dizziness, and loss of control over one’s actions and situation.
At altitude, air pressure drops, so when you inhale, you receive less oxygen. He develops symptoms of oxygen starvation: a feeling of weightlessness, headaches, increased fatigue, drowsiness, difficulty breathing.
Many people think that air has no weight. This is not true: one cubic meter of air, at standard pressure and altitude approximately at sea level, is 1.225 kg.
To breathe, a person on average needs about 20 kilograms of air per day, 15-16 cubic meters. To understand how much this is, you can imagine a cube with a side of approximately 2.5 m. A quarter of this volume is consumed by the brain.
Many people think that street air is dirtier than home air, 
because there is dust, garbage, exhaust fumes and gases emitted by industrial enterprises on the street. In fact, researchers have found that indoor air is about 25 times dirtier than outdoor air. In addition, if you do not ventilate, the percentage of oxygen in the room air decreases and the percentage of carbon dioxide increases, which has a bad effect on your well-being. So ventilate your home and work often!
We remind you that in the PrayChemicalsGroup store you can buy both thermometers for measuring air temperature and hygrometers for measuring air humidity. We have delivery, and the prices are quite affordable.
For many billions of years, our Earth, surrounded by a layer of air, has been making its endless run around the Sun.
This layer of air is called the atmosphere. Its thickness reaches 300 km. The atmosphere, like a transparent, invisible blanket, envelops our Earth. What is air, what are its properties and role in life on Earth?
Where is the air and why do we need it?
Air fills all empty spaces, and even the smallest cracks.
A transparent glass only appears empty. Try slowly tilting it and immersing it in water. As the glass fills with water, air will come out of it in large bubbles.
What is the role of air in life on our planet:
- Without air life on Earth would be impossible. A person can survive without food for several weeks, without water for several days, and without air for only a few minutes. Try to stop breathing for a while. Within a few seconds you will feel the need to take a deep breath. Animals also need air in the same way.
- And also air helps us communicate. The sounds produced vibrate the air. The resulting sound waves cause the eardrum in the ears to vibrate. The vibrations are transmitted to the brain, which perceives them as sound. There is no atmosphere on the Moon, so there is absolute silence there. And you can only communicate using special devices or gestures.
- In a huge ocean of air, winds and clouds, thunderstorms and auroras are born. He protects us from meteorites, dangerous ultraviolet and thermal radiation emanating from the Sun. Thanks to this airy “coat”, the Earth is not afraid of space cold either.
- Thanks to the air, planes and helicopters plow the sky, and huge airships hang. Flocks of birds fly in the blue sky, huge birds - hunters - soar motionlessly. Lifting force keeping them in flight occurs due to air flowing around the curved surfaces of their wings.
- Fish, thanks to their gills, are able to breathe air contained in the water.
The ocean of air surrounding our planet held by the forces of gravity. If the Earth lost its air shell, it would turn into a lifeless desert, devoid of vegetation.
What is air made of?
Only two centuries ago scientists learned that air is mixture of several gases: nitrogen, oxygen and carbon dioxide. Other planets also have atmospheres: , and huge giant planets. Mars and Venus are similar to Earth in many ways, but there is no life on them because the composition of the atmosphere is different.
Oxygen is most important for breathing. Without it, we cannot obtain the energy necessary for life from food. During physical work and sports, we breathe deeper and more often to replenish the energy expended for this activity.
There is a simple experience that allows you to get oxygen even at home. Pour regular potassium permanganate into the test tube (about 1/4). We fix it in a vertical position over the fire of a gas burner or alcohol lamp. Let it stand for 1-2 minutes and bring a smoldering splinter to its open end. The torch flashes brightly. The gas released when heated supports combustion and is called oxygen.
And in the next experiment we we get carbon dioxide, which does not support combustion. Place two candles of different heights in a box with a solution of citric acid (vinegar). Let's light them up. Then carefully add soda to the solution. A fairly violent reaction occurs. The candles go out one by one. Small at first, then taller. The lower candle went out first, which means that carbon dioxide is heavier than oxygen and it accumulates at the bottom.
Water constantly evaporates from the surface of all reservoirs, soil and vegetation. So in the air always contain water vapor. The humidity of air masses, the formation of clouds and rain clouds depend on their quantity.
What are the properties of air?
The following considerations will help us answer this question:
- Does air have color? No, the air is transparent. If it had color, it would color surrounding plants and objects.
- Why is the sky blue? The fact is that sunlight consists of 7 colors, like a rainbow. As it passes through the atmosphere, the blue color intensifies. That's what we see.
- If you take 2 rubber balls and inflate them (to the same size), they will take a round shape. This means that the pressure of the blown air was transmitted equally in all directions.
- Now place one of the inflated balloons in the refrigerator and the other in a bucket of warm water. After 10-15 minutes, the cooled ball will decrease in size, and the heated one will increase. Therefore, the air When heated it expands and when cooled it contracts.
- If you have a syringe without a needle at home, pinch its tip with your finger and try to compress the air in the syringe with the piston. The air volume will noticeably decrease. Release the piston - the air volume will return to the same level. Therefore, the air elastic
- In frosty weather, people put on fur coats and warm coats, and birds ruffle their feathers to trap air between the fibers and feathers. Because the air is poor conductor of heat. Therefore, plants under a blanket of snow do not freeze even in extreme cold.
Man has learned to use all these wonderful properties of air in everyday life. Let us remember the elastic tires of cars and bicycles, pumps and many other inventions of mankind. The air makes light yachts and huge sailing ships rush across the waves, rotates the wings of windmills, and makes the ball bounce.
Where is the cleanest and healthiest air?
We need clean air to breathe with sufficient oxygen content. But in cities where all the roads are clogged with cars, the air is polluted by their exhaust gases. Add pollution and emissions from factory pipes. Sometimes they form harmful smog, which hangs over the city like clouds, making it difficult to breathe.
But in forests and parks it is very easy to breathe, because our green helpers absorb harmful carbon dioxide and release oxygen. Seaweed also produces oxygen, which is why the air on the sea coast is so healing.
But now people are trying to reduce harmful emissions into the atmosphere. Car engines are being created that run on electric and even solar energy. Instead of smoking thermal chimneys, nuclear and solar power plants are being built.
If this message was useful to you, I would be glad to see you
Air is in us and around us; it is an indispensable condition for life on Earth. Knowledge of the properties of air helps a person to successfully use them in everyday life, farming, construction and much more. In this lesson we will continue to study the properties of air, conduct many exciting experiments, and learn about the amazing inventions of mankind.
Topic: Inanimate nature
Lesson: Properties of Air
Let us repeat the properties of air that we learned about in previous lessons: air is transparent, colorless, odorless, and does not conduct heat well.
On a hot day, window glass is cool to the touch, and the window sill and objects standing on it are warm. This happens because glass is a transparent body that allows heat to pass through, but does not heat up itself. The air is also transparent, so it allows the sun's rays to pass through well.
Rice. 1. Window glass conducts the sun's rays ()
Let's carry out a simple experiment: lower a glass turned upside down into a wide vessel filled with water. We will feel a slight resistance and see that the water cannot fill the glass, because the air in the glass does not “give” its place to the water. If you tilt the glass slightly without removing it from the water, an air bubble will come out of the glass and some of the water will enter the glass, but even in this position of the glass, the water will not be able to fill it completely.
Rice. 2. Air bubbles come out of the tilted glass, giving way to water ()
This happens because air, like any other body, occupies space in the surrounding world.
Using this property of air, man learned to work underwater without a special suit. For this purpose, a diving bell was created: people and the necessary equipment stand under the bell-cap, made of transparent material, and the bell is lowered under the water using a crane.
The air under the dome allows people to breathe for a while, long enough to inspect the damage to a ship, bridge supports or the bottom of a reservoir.
To prove the following property of air, you need to tightly cover the hole of the bicycle pump with your left hand and press the piston with your right hand.
Then, without removing your finger from the hole, release the piston. The finger with which the hole is closed feels that the air is pressing very hard on it. But the piston will move with difficulty. This means that air can be compressed. Air has elasticity because when we release the piston, it returns to its original position.
Elastic bodies are those that, after compression stops, return to their original shape. For example, if you compress a spring and then release it, it will return to its original shape.
Compressed air is also elastic; it tends to expand and take its original place.
In order to prove that air has mass, you need to make a homemade scale. Attach the deflated balloons to the ends of the stick using tape. Place the long stick in the middle of the short one, so that the ends balance each other. Let's connect them with thread. Attach a short stick to two cans with tape. Let's inflate one balloon and attach it to the stick again with the same piece of tape. Let's install it in its original place.
We will see how the stick tilts towards the inflated balloon, because the air filling the balloon makes it heavier. From this experiment we can conclude that air has mass and can be weighed.
If air has mass, then it must exert pressure on the Earth and everything on it. That’s right, scientists have calculated that the air in the Earth’s atmosphere exerts a pressure of 15 tons on a person (like three trucks), but a person does not feel this, because the human body contains a sufficient amount of air, which exerts a pressure of the same force. The pressure inside and outside is balanced, so the person does not feel anything.
Let's find out what happens to air when heated and cooled. To do this, let’s conduct an experiment: heat a flask with a glass tube inserted into it with the heat of our hands and see that air bubbles come out of the tube into the water. This happens because the air in the flask expands when heated. If we cover the flask with a napkin soaked in cold water, we will see that the water from the glass rises up the tube, because when cooled, the air is compressed.
Rice. 7. Properties of air during heating and cooling ()
To learn more about the properties of air, let's conduct another experiment: we attach two flasks to a tripod tube. They are balanced.
Rice. 8. Experience in determining air movement
But if one flask is heated, it will rise higher than the other, because hot air is lighter than cold air and rises. If you attach strips of thin, lightweight paper over a flask of hot air, you will see how they flutter and rise upward, showing the movement of heated air.
Rice. 9. Warm air rises
Man used knowledge of this property of air to create an aircraft - a hot air balloon. A large sphere filled with heated air rises high into the sky and can support the weight of several people.
We rarely think about it, but we use the properties of air every day: a coat, hat or mittens do not warm themselves - the air in the fibers of the fabric does not conduct heat well, therefore, the fluffier the fibers, the more air they contain, and therefore the warmer the thing, made from this fabric.
The compressibility and elasticity of air is used in inflatable products (inflatable mattresses, balls) and tires of various mechanisms (cars, bicycles).
Rice. 14. Bicycle wheel ()
Compressed air can stop even a train at full speed. Air brakes are installed in buses, trolleybuses, and subway trains. The air provides the sound of wind, percussion, keyboard and wind instruments. When the drummer hits the taut drum skin with his sticks, it vibrates and the air inside the drum produces sound. Hospitals have ventilators installed: if a person cannot breathe on his own, he is connected to a device that delivers oxygen-enriched compressed air into the lungs through a special tube. Compressed air is used everywhere: in book printing, construction, repairs, etc.
How a person uses the properties of air is presented in this article.
How does a person use the properties of air?
Air is used by humans in a variety of ways.
- The most important thing is breathing. After all, the air itself contains oxygen, and we breathe it, we need it.
- Such a simple function of the human body as hearing would be absolutely impossible if the air did not contribute to the propagation of sound vibrations.
- The property of air is compression, used in various pneumatic devices, from the simplest pistols to various jackhammers and the like.
- The creation of air support is widely used both in aviation and in similar sectors of the national economy.
- Balloons, aerostats, and other such aircraft that are lighter than air also use this property of mass.
- With the help of winds, sailing ships move, and windmills and wind power plants rotate.
- Oxygen is a vital condition for a process such as combustion, and this, of course, also uses the properties of air.
Thus, we have come to the unequivocal and final conclusion that the use of the properties of air is very important for the very existence of humanity, and all life on Earth.
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