What are the characteristics of air?

Approximately: nitrogen 78%, oxygen 21%, noble gases, carbon dioxide, other gases and impurities Aerodynamics is a branch of mechanics, which mainly studies the mechanical characteristics of objects in relative motion with gases, gas flow laws and accompanying physicochemical changes. It is a discipline that has grown up on the basis of fluid mechanics with the development of the aviation industry and jet propulsion technology.

If we want to continue to introduce a brief history of the development of aerodynamics and the research content and research methods, it will take a long time.

Discus, kites, and bats all follow aerodynamic principles in the air, while bees are typical of those who do not.

Characteristics of air:

Occupies space, has no fixed shape, has fluidity, is easily compressed, and has weight. The air is transparent, colorless and odorless, it is mainly composed of nitrogen and oxygen, which has an important impact on human survival and production.

Description. 1. The air is directly invisible, intangible, colorless, odorless and transparent gas.

An ordinary plastic bag can be prepared. Tie the bag tightly with your hand. You can see the pockets bulging. It's air.

2. Occupy space.

Place a plain napkin in a beaker. Then place the beaker upside down in the sink and submerge it all. Take it out, why is this piece of paper not wet? It turned out that the beaker was filled with air, and the air took up the space, providing a dry environment for the paper.

3. It will flow.

One beaker is filled with air and the other is filled with water. When we tilt the beaker filled with air, since the air is lighter than the water, the air will flow upwards into the water-filled beaker above, and the water will be driven out. Air flows upwards in water.

Features are:

1. It can flow and have wind;

2. It can accept harmful gases, resulting in opening pollution;

3. The gas content of the pollutant can be diluted, the concentration of the pollutant can be reduced, and the pollution can be eliminated;

4. Promoting air flow is a good way to control air pollution.

5. The air can be compressed to reduce the volume. Conforms to the gas equation of state.

1) In its natural state, air is colorless and odorless;

2) Air has mass;

3) Air has weight;

4) Air has volume, and in different environments, its volume will change, that is, the density is variable;

5) Air is thermally conductive.

In this air, you should also know some of the components it contains, after all, there must be carbon dioxide and oxygen, so pushing can also support combustion, and it can also allow human beings to live.

Air is compressible, and the air after the air compressor does mechanical work to reduce its volume and increase the pressure is called compressed air. Compressed air is an important power source. Compared with other energy sources, it has the following obvious characteristics:

Clear and transparent, easy to convey, no special harmful properties, no danger, not afraid of overload, can work in many unfavorable environments, air is everywhere on the ground, inexhaustible.

Air occupies a certain space, but it does not have a fixed shape and volume. When pressure is applied to the air in a closed container, the volume of the air is compressed, increasing the internal pressure. When the external force is withdrawn, the air returns to its original volume under the action of internal pressure.

If there is an object in the container that can move, when the air returns to its original volume, the object will be pushed outward by the pressure of the air inside the container.

Air is a colorless and odorless gas that can be compressed into high-pressure air to inflate tires, air is everywhere, and it is difficult to find a vacuum in nature! If you think this answer is a little inspiring, please click on the "....Then click "Accept".

Air refers to the mixture of gases in the earth's atmosphere, therefore, the composition of air is quite complex, however, air specifically refers to the mixture of gases in which the vast majority of organisms on the earth can live;

So, 1) in its natural state, air is colorless and odorless; 2) Air has mass; 3) Air has weight; 4) Air has volume, and in different environments, its volume will change, that is, the density is variable; 5) Air is thermally conductive.

Lesson 1 "Feel the Air".

1.Air energy.

It occupies space, the shape is not fixed, it has mass, but it is light.

2.Air is colorless, transparent, odorless, and flowing.

3.Air is everywhere on Earth.

4.Air contains nitrogen, oxygen, carbon dioxide.

Wait. 5.The oxygen in the air helps the burning of matches, and plants and animals need to breathe air.

6.Air bubble map.

Characteristics, composition, role.

Lesson 2 "Can Air Take Up Space".

1.Before punching, air occupies space and water cannot enter the cup; After punching, the air flows out and the water enters the cup; After pumping, the air reoccupies the space and the water in the cup is significantly reduced. Conclusion: Air occupies a certain amount of space and fills everywhere.

Lesson 3 "Compressed Air".

1.Air occupies a certain amount of space, and the space occupied by air can be compressed or expanded.

2.Compressed air is resilient.

Lesson 4 "Does Air Have Mass".

1.Air has a certain mass.

2.Mass is one of the essential characteristics of air and can be measured.

3.Mass is one of the essential properties of all substances, and air, as a substance, has mass.

Lesson 5 "What is the mass of a bag of air".

1.When measuring air quality, select "light, weight, and size objects" as the measurement standard.

2.Objects of the same mass may have different volumes.

Lesson 6 "Let's Make a Hot Air Balloon."

1.Hot air will rise and cold air will fall.

2.Hot air balloon ascent principle: When the air in the pocket is heated, the volume expands and the weight becomes lighter, so it will rise.

3.Hot air balloon descent principle: After being away from the heat source, the air in the pocket becomes colder, the volume decreases, and the weight becomes larger and falls.

Lesson 7 "The Causes of the Wind".

1.The rise of hot air causes air movement.

2.When hot air rises, the vacated area (low pressure area) will be filled by nearby cold air, creating the wind we normally feel.

3.The hot and cold changes in the air cause air to flow, which is the main reason for the formation of natural winds.

Lesson 8 "Air and Our Lives".

1.The earth is surrounded by a thick layer of air, which people call the atmosphere.

2.Oxygen and carbon dioxide in the air are important for life.

3.Air can help with combustion.

4.Wind has energy, and wind energy is a clean and renewable energy source.

Air is one of the four classic elements – air, water, earth, and fire.

1.It has an indeterminate shape and volume.

2.It has no color and no smell.

3.It has mass and weight because it is a substance.

4.The weight of the air creates atmospheric pressure.

5.There is no air in outer space.

6.Air is a mixture of 78% nitrogen, 21% oxygen, argon, carbon dioxide and a small amount of other gases. On average, there is about 1% water vapor.

7.Animals live on aerobic respiration and need to breathe oxygen from the air. During breathing, the lungs pump oxygen into the bloodstream and carbon dioxide back into the air.

Plants need carbon dioxide from the air to survive. They release the oxygen we breathe. Without it, we would die of suffocation.

8.The wind makes the air move, which causes the weather.

9.The air can be contaminated with some gases (such as carbon monoxide), smoke, and dust. This air pollution causes a variety of problems, including smog, acid rain, and global warming. It can harm people's health.

10.Airplanes use propellers to pass air through the wings, which allows them to fly.

1. Knowledge points about air.

1 The composition of air is calculated by volume fraction, and nitrogen accounts for 1%.

Seven. Ten. 8. Oxygen accounts for 10 percent.

Two. Ten. 1. Rare gas accounts for 0 percent.

Nine. Fourth, carbon dioxide contains 0.03 percent.

2. How to prove that the air contains nitrogen, oxygen, water vapor and carbon dioxide?

Air can make nitrogen fertilizer, which proves that there is nitrogen in the air.

The fact that the wooden strips burn in the air proves that there is oxygen in the air.

Crispy biscuits that soften when left in the air for a while are evidence of water vapor in the air.

The clarified lime water is left in the air for a period of time and becomes cloudy, proving that there is carbon dioxide in the air.

3. The purpose of filling nitrogen in the bulb is to prolong the service life of the bulb, and the purpose of filling nitrogen in the food bag is to prevent corrosion.

4. Nitrogen can be flushed in food bags, and the reason for its antiseptic is that nitrogen is chemically inactive.

5 Sulfur dioxide, carbon monoxide, nitrogen dioxide, respirable particulate matter, and ozone are tentatively designated as air pollution indexes.

6. Experiment to determine the oxygen content in the air.

1) Purpose: To determine the oxygen content in the air.

2) Phenomenon: At the beginning, white smoke comes out of the combustion of red phosphorus, and after cooling, the water enters the gas cylinder along the conduit, and the volume of water entering the water is about equal to one-fifth of the volume of air in the gas cylinder.

Today, the teacher asked us to do a small experiment, the teacher first took out two balloons that did not blow air, and then took out the scale made by himself, the scale has a yellow wooden stick, and a red line tied to the positive ** of the wooden stick, the teacher finally took a needed prop double-sided tape.

The teacher first attached double-sided tape to both sides of the stick, and then glued two balloons that did not blow air to the sides of the scale. It turned out to be as heavy as two balloons that didn't blow air.

Then the teacher invited a student to come up to the stage to blow up the balloon, and the student gently held the balloon's bulging cheeks and blew it with all his strength, but he still couldn't blow the balloon big.

The teacher invited another student to come up to the stage to blow up the balloon, and the student easily held the balloon in his hand and easily blew the balloon into a balloon twice the size of his own. ”

Finally, the teacher tied the blown balloon with a rubber band.

Then the teacher glued the blown balloon and the unblown balloon on it, and this time, the weight on both sides was different, and we saw it, which was incredible. After the first experiment, the teacher told us to play breath holding, and the game began, and the students closed their mouths and pinched the box tightly, but the students' faces turned blue, as if they were struggling and couldn't hold on, but the students were still persistent. Seeing that my classmates were almost unable to hold on, I felt very uncomfortable in my own heart.

In the end, the teacher came to the conclusion that people are inseparable from air, just as fish cannot do without the sea.

Teacher's comment: Qin Tao, your essay is very complete, and some good words and sentences are used, which makes the essay more active. After the first experiment, do you understand anything? The second experiment begins, so pay attention to the transition.