Air and not a lot of weight. Does air have weight? Which air is the heaviest

City Scientific and Practical Conference

"Planet of the Erudite"

Does air have weight?

The world

4 "A" class, MBOU secondary school No. 14

Supervisor:

Dzerzhinsk

2013

2. Air cleaning.

3. Air has weight.

4. Conducting experiments.

Introduction

Our entire planet is shrouded in a transparent veil - air. We don't see it, we don't feel it. But if it suddenly disappears, water and all other liquids will instantly boil on Earth, and the rays of the Sun will burn all living things.

A person can go without food for five weeks, without water for five days, and without air for a maximum of five minutes. Air is needed by humans, animals, and plants to breathe, and therefore to live. And the wind? It's air movement! Without wind, clouds would always be above the sea or river. This means that rain without wind could only fall over water. Under the action of air and water, geological processes take place on the surface of the Earth, weather and climate are formed. By burning fuel (and oxygen, a component of air, must necessarily participate in this), people have long received heat, which is necessary both in everyday life and in production.

Air is the most important source of chemical raw materials. Just two centuries ago, scientists learned that air is a mixture of many gases, mainly oxygen and nitrogen, argon and carbon dioxide. Due to the urgency of this problem, we have identified the following purpose of the study: determine if air has weight?

Research objectives:

Review best practices on air science;

Determine the properties of air;

Conduct an experiment to determine the weight of air;

Draw conclusions.

1. Importance of air for humans.

For a person, temperature, humidity, air movement are of great importance. For example, if you are lightly dressed and engaged in simple work, the best air temperature is 18-20 C. The harder the work, the lower the air temperature can be, but not so much that it becomes difficult to breathe, as in severe frost. People feel best when the air humidity is 40-60 percent. Dry air is usually well tolerated, and high air humidity has an unfavorable effect: at high temperatures, the body overheats, and at low temperatures, it becomes supercooled.

2. Air cleaning.

The amount of carbon dioxide, chemical compounds that are emitted by industrial enterprises and cars is growing in the air.

There is a widespread movement in the world in defense of nature. We have passed laws and are developing new ones, according to which the heads of enterprises are responsible for cleaning and neutralizing gases before they are released into the atmosphere.

Plants, the lungs of the planet, play a huge role in air purification. They trap dust, soot, absorb carbon dioxide and release oxygen. Among other natural filters, poplar and sunflower are the best at purifying air from pollution. Studies have shown that on busy highways, along which pyramidal poplars were planted and sunflower fields stretched, the air remained clean.

3. Air has weight.

Air has weight. In a liter bottle, for example, there is more than one gram of air. With its weight, the air presses on us and on all objects around us. If, for example, you pump out air from a tin can, it will flatten.

At a temperature of 0 °C and normal atmospheric pressure, the mass of air with a volume of 1 m3 is 1.29 kg.

4. Conducting experiments.

Experience can prove that air has weight. In the middle of a stick sixty centimeters long, we will strengthen the rope, and we will tie two identical balloons to both ends of it. Let's hang the stick by the string and see that it hangs horizontally. If you now pierce one of the inflated balloons with a needle, air will come out of it, and the end of the stick to which it was tied will rise up. If you pierce the second ball, then the stick will again take a horizontal position.

This happens because the air in the inflated balloon is denser, and therefore heavier, than the one that is around it.

Another experience:

Get an empty clear plastic bottle. This experience will show whether it is as empty as it seems. Dip the bottle into the basin of water so that it begins to fill. See what happens to the water. You can see bubbles coming out of the neck. It is the water that displaces the air from the bottle. Most things that look empty are actually filled with air.

Feel the air

Is there air around? It's very easy to find out. Wave a piece of cardboard in front of your face. The cardboard will make the air move and you will feel it blow on your face.

Paper racing.

Air can move objects. We propose to arrange such a game: each player will need a piece of cardboard and a sheet of paper. One side of the sheet needs to be bent. Instead of finishing tape, stretch the thread. Now, on command, wave the cartons behind the sheets of paper, and the air will move them forward.

Heavy newspaper.

Take half a piece of newspaper and spread it out on the table. Place a ruler under the newspaper so that its end protrudes beyond the edge of the table. Click on the ruler and try to tear it off the table.

It turns out that this is not so easy to do, because air pressure presses the newspaper against the table.

Flattened package.

For the experiment, take a small juice bag with a hole for the tube. Suck out the juice from the bag through a straw. Keep pulling air through it. See what happens. When part of the air leaves the bag, the outside air will squeeze its walls. Take out the straw and look at the bag.

The walls parted again, because the air entered the bag and straightened it. See what happens to the bag if you blow even more air into it.

Thus, we have proved that air has weight.

Conclusion.

How much air weighs depends on when and where it is weighed. The weight of air above a horizontal plane is atmospheric pressure. Like all objects around us, air is also subject to gravity. This is what gives the air a weight that is equal to 1 kg per square centimeter. The density of air is about 1.2 kg / m3, that is, a cube with a side of 1 m, filled with air, weighs 1.2 kg.

An air column rising vertically above the Earth stretches for several hundred kilometers. This means that a column of air weighing about 250 kg presses on a person standing straight, on his head and shoulders, the area of \u200b\u200bwhich is approximately 250 cm2!

By the way...

In everyday life, when we weigh something, we do it in air, and therefore we neglect its weight, since the weight of air in air is zero. For example, if we weigh an empty glass flask, we will consider the result obtained as the weight of the flask, neglecting the fact that it is filled with air. But if the flask is closed hermetically and all the air is pumped out of it, we will get a completely different result ...

Bibliography

1. "Ecology, environment and man"

2. Encyclopedia "The World Around Us"

3. Website http://*****/

How much does air weigh and does it weigh at all? We live inside the air, surrounded by it, and do not feel its weight. It may seem that he is weightless. In fact, air has volume and mass. And we feel it when the wind blows - the wind bends the trees to the ground, tears off the hats from the heads.

Does air have weight?

Air does have weight! There is an easy way to be sure.

Take 2 balloons and a straight stick. Tie the balls from different ends of the stick (the length of the threads should be the same). Now tie a rope exactly in the middle of the stick. If everything is done correctly, then holding the rope, the stick will be in a horizontal position - a kind of scales have turned out. Now take one of the balloons and inflate it even more. What will happen? The side of the stick with the balloon you just inflated will be lower because the balloon now has more air and weighs more.

But a fair question may arise - why does a balloon that is filled with air and surrounded by air on the outside weigh more? The answer lies in density.

In a liquid, everything that has a greater density than the environment will sink. When you added air to the balloon, you increased its overall density, since the air inside the balloon is under b about more pressure than outside. More pressure means more density, so the heavy air inside the balloon outweighs the balloon with less air.

How much does air weigh?

At the Earth's surface, one cubic meter of air weighs about 1.25 kg(data for dry air).

Although we do not feel the air around us, the air is not nothing. Air is a mixture of gases: nitrogen, oxygen and others. And gases, like other substances, are composed of molecules, and therefore have weight, albeit small.

This is because the air in the inflated balloon denser, which means that heavier than the one around it.

How much air weighs depends on when and where it is weighed. The weight of air above a horizontal plane is atmospheric pressure. Like all objects around us, air is also subject to gravity. This is what gives the air a weight that is equal to 1 kg per square centimeter. The density of air is about 1.2 kg / m 3, that is, a cube with a side of 1 m, filled with air, weighs 1.2 kg.

We would not be able to withstand such a weight if it were not opposed by the same pressure inside our body. The following experience will help us understand this. If you stretch a paper sheet with both hands and someone presses a finger on it from one side, then the result will be the same - a hole in the paper. But if you press two index fingers on the same place, but from different sides, nothing will happen. The pressure on both sides will be the same. The same thing happens with the pressure of the air column and the counter pressure inside our body: they are equal.

Air has weight and presses on our body from all sides.
But he cannot crush us, because the counter pressure of the body is equal to the external one.
The simple experience depicted above makes this clear:
if you press your finger on a sheet of paper on one side, it will tear;
but if you press on it from both sides, this will not happen.

By the way...

Svetlana Chebysheva

Experience number 1. "Where is the air hiding?"

Equipment: cellophane bags, toothpicks.

Tell me, can you see the air around us? (no, we don't see)

So what is air? (invisible).

Let's catch some air.

Take plastic bags from the table and try to catch air.

Roll up the packages.

What happened to the packages? (they puffed up, took shape)

Try squeezing the package. Why doesn't it work? (there is air inside)

Where can this property of air be used? (inflatable mattress, life buoy).

Let's conclude: Air has no form, it takes the form of the object into which it enters.

Now look at your hand through the bag. Do you see a hand? (we see).

So what is air? (it is transparent, colorless, invisible).

Let's check, is there really air inside?

Take a sharp stick and carefully pierce the bag. Bring it to your face and press it with your hands.

What do you feel? (hiss).

This is how air comes out. We don't see it, but we feel it.

What can be concluded now? Air cannot be seen, but it can be felt.

Conclusion: Air is transparent, invisible, colorless, without form.

Experience number 2. "How to see the air?"

Equipment: straws for a cocktail, glasses with water.

Blow through the tube onto your palm.

What did the palm feel? (air movement - breeze).

We breathe air through the mouth or through the nose, and then we exhale it.

Can we see the air we breathe?

Let's try. Immerse the tube in a glass of water and blow.

Bubbles appeared on the water.

Where did the bubbles come from? (This is the air we exhaled).

Where do the bubbles float - rise up or sink to the bottom?

(Air bubbles rise up).

Because air is light, it is lighter than water. When all the air is out, there will be no bubbles.

Conclusion: Air is lighter than water.

Experience number 3. "Air is invisible"

Equipment: a large transparent container with water, a glass, a napkin.

At the bottom of the glass, you need to fix a paper napkin. Turn the glass upside down and slowly lower it into a container of water.

To draw the children's attention to the fact that the glass must be held very evenly. They took the glass out of the water and touched the napkin, it was dry.

What happens? Does water get into the glass? Why not?

This proves that there was air in the glass, which kept the water out of the glass. And since there is no water, it means that she cannot wet the napkin.

The children are invited to lower the glass into the jar of water again, but now they are invited to hold the glass not straight, but slightly tilted.

What appears in the water? (visible air bubbles).

Where did they come from? Air leaves the glass and water takes its place.

Conclusion: The air is transparent, invisible.

Experience number 4. "Air Movement"

Equipment: Fans made from colored paper in advance.

Guys, can we feel the movement of air? What about seeing?

When walking, we often observe the movement of air. (trees sway, clouds run, turntable spins, steam from mouth).

Can we feel the movement of air in the room? How? (fan).

We cannot see the air, but we can feel it.

Take the fans and wave them in the face.

What do you feel? (Feel the air moving).

Conclusion: The air is moving.

Experience number 5. "Does air have weight?"

Equipment: two equally inflated balloons, a toothpick, scales ( can be replaced with a stick about 60 cm long. Fasten a rope in its middle, and balloons at the ends).

Invite the children to think about what would happen if you pierced one of the balloons with a sharp object.

Poke one of the inflated balloons with a toothpick.

Air will come out of the balloon, and the end to which it is tied will rise up. Why? (The balloon without air has become lighter).

What happens when we pierce the second ball too?

Poke a second ball with a toothpick.

You will regain your balance. Balloons without air weigh the same as inflated ones.

Conclusion: Air has weight.

When we want to emphasize the lightness, almost "weightlessness" of something, we usually say "air", thereby emphasizing that the air seems to us to be something without weight. People have been sure of this for many centuries, and confidence was reinforced by the authority of such a respected scientist as Aristotle. This great ancient Greek philosopher once wondered if air had weight. As befits a scientist, he decided to test this in an experiment. On one side of the scales he placed a leather skinskin inflated with air, on the other - the exact same skinskin, only empty. The scales are balanced, therefore, the air weighs nothing!

Let's not judge strictly: at that time, physics was only in its infancy, and Aristotle, like any pioneer, could not avoid mistakes. To understand what the great scientist's mistake was, let's remember the exact meaning of the word "weight": the force with which the body acts on a support or suspension. What we call weight in everyday life and measure in kilograms is mass, the property of bodies to change their speed when a force is applied to them. There is no need to confuse these concepts: in weightlessness, bodies lose weight, not mass, so that in a spaceship the cabinet will hang in the air, but it will not be easier to move it from its place than on Earth. So, it is weight that is measured with the help of scales, but this weight corresponds to a certain mass, and since it is mass that interests us, for simplicity, we are talking about grams and kilograms, and not about Newtons, in which force is measured, but measured - that is precisely the force, it is precisely with the force that the error came out. When the leather skinskin was inflated, its volume increased, therefore, the buoyancy force of the surrounding air acting on it changed (the law of Archimedes, which had not yet been discovered at the time of Aristotle), so the scales were balanced.

G. Galileo went the other way. He weighed not a bag, but a hollow copper ball, which cannot change its volume. The researcher put it on the scales, and then pumped out the air from the balloon. And what? The ball has become lighter! This meant that the "weightless" air weighed!

At that time, such a statement could look extremely bold (it's no joke - to argue with Aristotle himself, whose views were "sanctified" by the authority of the Catholic Church!), But now we understand that this is logical. In order for a body to have weight (i.e., to act on a support), in essence, little is needed - for the force of gravity to act on it. It works on air. If this were not so, we would not have an atmosphere left, all the atoms of the gases that make it up would fly apart in outer space, therefore, the air also has a weight that acts on the earth's surface and everything that is on it. This weight is really small - a thimble of water, for example, weighs more than a liter of air, but ... there is a lot of it! If we take air from the earth's surface to the top of the atmosphere over an area of one square centimeter, this will be the weight corresponding to one kilogram. The area of the human palm is about 70 square centimeters, therefore, the air has such an effect on it as if we were holding an object weighing 70 kg in the palm of our hand! And on the human body as a whole, the air acts with a force corresponding to 15 tons, these are three five-ton trucks!

But we do not feel this heaviness for one simple reason: there is also air inside our body, and it acts with the same force, balancing the weight of the air outside. It cannot be otherwise, because our biological species originated on this planet, in the conditions of this atmosphere. But the atmosphere of Venus, for example, would crush us in no time!