Why ice does not sink in water, but floats on its surface. Do we know everything about the properties of ice? How to explain complex physical processes to a child

To begin with, the places where polar research is carried out are dominated by a polar climate. These places are usually the Arctic and Antarctic.

The difference between the Arctic and Antarctic

Antarctica, which is part of Antarctica, is the coldest continent on the planet, temperatures in summer reach -30 ° C, in winter - -60°C. It also recorded the lowest temperature on the planet - -91.2 ° C. As for the Arctic, the climate here is not so severe. The Arctic includes the islands of the Arctic Ocean, which thaws in summer.

Types of modern equipment and equipment

In the Arctic and Antarctic, when sent on an expedition in the summer, temperatures drop only to -45 ... 50 ° C. To withstand such a "light" temperature, polar explorers use special overalls. Today the popular suits of the ECWCS family belong to the third generation. Overalls manufacturers assure that they maintain a comfortable temperature inside, even at -60 ° C.

The variety of footwear of our polar explorers has not changed since the times of the USSR. They use high fur boots, felt boots and rubber boots. Although the assortment has not changed, the shoe filler has undergone a correction, for example, earlier high fur boots were made from fox fur, and now from refined sheepskin. Fur boots are the most uncomfortable shoes, unlike boots with rubber soles.

No matter how strange it may sound, polar explorers need personal weapons. Everyone knows that a large number of wild animals live within the polar belt, some of them are dangerous for the researcher. Therefore, weapons are used against polar bears, walruses, and elephant seals.

Polar explorers study ice, oases, the origin and structure of ice. DAll of these studies require special equipment. Ice picks, ice axes and special ice saws are used to study ice. While searching for oases, polar explorers travel enormous distances along the coast. But geologists, to study the origin of ice, use a drill hammer, air and gas photography.

Let me summarize. What do polar explorers need:

• specialized overalls;
• insulated shoes;
• personal weapons;
• research tools.

Think about what precautions you need to take when going to the pole ADDITIONAL Precautions at the poles:
-Going to the pole, take with you as much warm clothes as possible
-If it's summer at the Pole, the temperature can still reach 0. In this case, you need to follow the rules for moving on fragile ice
In the event of a fall under the ice:
-do not panic
- call for help
- after getting out, crawl on the ice (do not get up, this will increase the pressure on the crust)
For frostbite:
- In case of frostbite of the 1st degree, the cooled areas should be warmed to redness with warm hands, light massage, rubbing with a woolen cloth, breathing, and then apply a cotton-gauze bandage.
- In case of frostbite II-IV degree, rapid warming, massage or rubbing should not be done. Apply a heat-insulating bandage to the affected surface (a layer of gauze, a thick layer of cotton, again a layer of gauze, and on top of an oilcloth or rubberized cloth). The affected limbs are fixed with the help of improvised means (a board, a piece of plywood, thick cardboard), applying and bandaging them over the bandage. Quilted jackets, jerseys, woolen fabric, etc. can be used as a heat-insulating material. The victims are given hot drinks, hot food, and a small amount of alcohol.

Topic: Arctic Ocean .

The purpose of the lesson: Form the concept of the Arctic Ocean as a natural community.

Educational: Formation of knowledge about the nature of the Arctic Ocean:To get acquainted with the inhabitants of the Arctic Ocean, to be able to explain the features of the adaptation of living organisms to living in the Arctic Ocean.

Developing: Develop the ability to work with information (process it in various ways, is critical of information), develop speech, memory.Determine the topic and objectives of the lesson; receive information from different sources;

​ analyze the read text.

Educational: educate curiosity, interest in the subject, broaden the horizons of students, develop a desire to learn new things,listen to the answers of comrades; listen and understand the teacher's speech.

Equipment: electronic presentation,textbook, map of natural areas of Russia, dictionary.

During the classes

I . Organizing time.

Hello guys. We have guests in class. Let's welcome them.

The world around us

Interesting to know

His secrets and mysteries

Are you ready to unravel?

Checking homework.

2. Updating knowledge

Guess the riddles:

It is made up of seas.
Come on, answer quickly.
This is not a glass of water
Ah, a huge ... ocean

There are many different bodies of water on the earth's surface. What do you think is the largest body of water? (ocean)

Readingin dictionary about what isocean.

(Ocean - part of the World Ocean, located between the continents)

How many oceans are on Earth? (4) Working with the world map.

What is the biggest? And which one is small?

What deep? Which one is not very deep?

What is the warmest ocean? And which one is the coldest?

Is there life in the ocean?

And in the cold?

Today we will look into this cold ocean.

2. Work on the topic of the lesson.

In what climatic conditions do you think the Arctic Ocean is located?

Yes, it's very cold there. Both flora and fauna, all must be adapted to the harsh living conditions.

If we go to the North for a long, long time, without turning anywhere and without deviating, then we will get to the North Pole. Since ancient times, this region of the Earth has been called the Arctic - from the Greek word arkticos - northern, as the ancient Greeks called the constellation Ursa Major located in the northern part of the sky

Today at the lesson we have another meeting of the club "We and the world around us." We dedicate it to the study of the Arctic Ocean. Let's divide into 4 groups: geographers, biologists, zoologists and ecologists. The meeting of our club will be held according to the plan: (on the board)

Location of the Arctic Ocean and features of inanimate nature (a group of geographers).

Plants of the Arctic Ocean (a group of biologists).

Animals of the Arctic Ocean (a group of zoologists).

The Arctic and people (a group of ecologists).

We give the floor to a group of geographers.

Location and features of inanimate nature

The Arctic Ocean is the coldest ocean in the world. Most of the surface of the ocean and its islands is covered with perennial ice up to 5 meters thick throughout the year. Only in some places on the islands there is no ice, but even here the earth freezes many meters deep. Soil is not formed on such islands.

The nature of the Arctic Ocean is very harsh. In winter there is POLAR NIGHT. From mid-October to February, the sun is not visible at all. Strong winds blow, a blizzard sweeps for weeks, the air temperature often drops to -60◦С. During the polar night you can observe one of the amazing natural phenomena - the NORTHERN LIGHTS. Eyewitnesses say that the aurora is like a bizarre curtain that sways in the dark sky. The curtain is divided into luminous multi-colored stripes, shining with the pure colors of the rainbow.

POLAR DAY in SLO in summer. There is light around the clock for several months. But the sun does not rise high above the horizon, and the temperature is rarely higher than 3-4◦С. Therefore, even during the long polar day, the age-old ice does not have time to melt.

Fizminutka .

Three bears were walking home.

Dad was big.

Mom is a little smaller.

Well, the son is just a baby.

He was very small

Walked with rattles.

Let's give the floor to a group of biologists.

Plants

Harsh natural conditions are tolerated only by resistant and unpretentious plants. Large areas are occupied by stone placers. There is almost no soil. In the summer, the snow melts in places, and the stones are exposed. On them - then LICHES grow, similar to gray scale. Lichens are amazing organisms. The bulk of the lichen is made up of the thinnest white or colorless tubules. These are mushroom threads. Any mushroom body consists of such tubules. And between the mushroom tubes are emerald balls. These are tiny algae. Yagel - like all lichens, consists of two organisms - a fungus and an algae, combined into one. When wet, reindeer moss is soft and elastic. But after drying, it becomes brittle, crumbles easily. Its smallest crumbs are easily carried by the wind and are able to take root. It is in this way that the reindeer moss basically reproduces. Yagel is the main food of reindeer. Deer unmistakably find it by smell even in winter under the snow.

In the southern regions of the ocean, you can find here and there POLAR POPPIES, creeping POLAR WILLOWS. They can easily be mistaken for herbaceous plants, because they are only 5-10 centimeters high.

Let's give the floor to the group of zoologists.

Animals

Walruses and seals are kept from freezing by a thick layer of subcutaneous fat. Walruses are close relatives of seals, large and strong, and few dare to attack them. They have two long fangs, which they use in combat and to get out of the water onto the ice to rest. Walruses have strong lips that allow them to suck edible molluscs from their shells. A walrus can eat 3,000 clams in a day.

The POLAR BEAR has thick fur that retains heat well. For days the giant of the Arctic wanders through the snowy desert in search of prey. It can lie for hours near a hole in the ice, waiting for a seal to emerge for a portion of air. Polar (white) bears are the largest and strongest animals of the Arctic Ocean, no one attacks them. In the middle of winter, their cubs are born in snow-covered lairs. The mother feeds them with her milk, but she herself does not eat anything until it is warm enough that she can go hunting. Polar bears have an excellent sense of smell and can run very fast across the ice, chasing prey. They swim and dive well. In summer they feed on grass, lichens, blueberries and lemmings.

On the rocky shores - bird colonies. Numerous seabirds nest here: puffins, guillemots, puffins, various types of gulls. Geese and ducks live along the coast. Among them, the most famous eiders have soft warm fluff. Some animals can live all year round in the Arctic Ocean. Other animals visit these places only in summer, when the ice melts and the sea is cleared of ice. Plants that grow in summer are the main food source for many animals.

What adaptations do they have to these living conditions?

Let's take one of the animal species and bring it to us.

For example: A polar bear, can it live in our conditions?

Why not?

Working with a book

- Guys, listen. Now I will ask you questions, and you must answer.

Let's see who of you is the most attentive and active.

What polar explorers do you remember?

What did the explorers think before?

What have you learned?

What is in the "Top" of the Earth?

What apparatus is used to study the ocean today?

Word to our environmentalists.

Arctic Ocean and man .

There are no permanent human settlements in the Arctic Ocean. However, people live here. The shortest route from the Atlantic to the Pacific runs through the Arctic Ocean. Therefore, caravans of merchant ships regularly move along the Northern Sea Route, with powerful icebreakers paving their way through the ice.

There are many scientific stations on the islands and in the ice of the Arctic Ocean. Here, polar explorers observe the weather, study where ice floes drift in the ocean, explore the nature of the North. The data they collect helps pave the way through the ice, and meteorologists make weather forecasts.

In the seas of the Arctic Ocean, people are engaged in fishing and hunting. Unfortunately, due to the fact that people are more and more mastering the SLO, its nature is in danger. Animals such aspolar bear, walrus, bowhead whale, white goose, musk ox.

Reserves have been created on the Taimyr Peninsula and on Wrangel Island to protect these rare animals.

Based on the plant and animal world, what can people do?

Despite the cold, we need the Arctic Ocean.

vocabulary work

What is a reserve?

Open the dictionary and find what is a reserve?

Fizminutka .

Moves to a song about penguins

4. Consolidation of the passed.

a) frontal survey:

Compare the natural conditions of your area with the natural conditions of the Arctic.

What plants and animals are typical for the Arctic zone?

Why have people been exploring the Arctic for a long time?

What measures are people taking to protect the nature of the northern region?

Why are the animals of the Arctic dominated by those fed by the sea?

b) power circuits:

Algae - crustaceans - fish - birds

Algae - crustaceans - fish - seals

Fish - seals - polar bears

c) Fill in the table of today's expedition (mutual check in pairs)

The Arctic - the realm of snow and ice

Geographical position

Arctic Ocean, northern seas, islands

illumination

Polar day and polar night, Northern Lights

Flora and fauna

Lichens, mosses, polar poppy, cranberries, cloudberries, crustaceans, fish, auks, polar bear, walrus, seal

human activities

Scientific stations, Northern Sea Route, fishing, hunting

d) solve the crossword: (on the board)

The solution of the crossword "SLO".

If you guess the crossword correctly, you will read the word in the center.

Questions.

1. These birds gather in the summer on rocky shores in noisy "bird colonies", they love to eat fish very much.

2. A close relative of the seal.

3. Birds that lay their eggs directly on bare rock ledges.

4. The polar bear loves to hunt them very much.

5. The most common plant in the polar regions.

6. The largest inhabitant of the seas and oceans.

7. Small inhabitants of the seas that feed on fish.

Answers. 1. Seagull. 2. Walrus. 3. Guillemots. 4. Seal. 5. Lichens. 6. Whale. 7. Crustaceans.

What did we learn in the lesson? (Work with the text; work in pairs, find the information you need)

What did you learn?

5. Homework. Prepare a story about the inhabitants of the Arctic Ocean.

- the smallest ocean on Earth, located between Eurasia and North America. Area 14.75 million sq. km, average depth 1225 m, maximum depth 5527 m in the Greenland Sea. The volume of water is 18.07 million km³.

This ocean is characterized by a harsh climate, an abundance of ice and relatively shallow depths. Life in it is completely dependent on the exchange of water and heat with neighboring oceans.

The Arctic Ocean is the smallest of the Earth's oceans. He is the shallowest. The ocean is located in the center of the Arctic, which occupies the entire space around the North Pole, including the ocean, adjacent parts of the continents, islands and archipelagos.

A significant part of the ocean area is made up of seas, most of which are marginal and only one is inland. There are many islands in the ocean located near the continents.

History of ocean exploration. The exploration of the Arctic Ocean is the story of the heroic deeds of many generations of sailors, travelers and scientists from a number of countries. In ancient times, Russian people, Pomors, traveled on fragile wooden boats and boats. We wintered on Grumant (Svalbard), sailed to the mouth of the Ob. They hunted fish, hunted sea animals and knew well the conditions of navigation in polar waters.

Using information about the voyages of the Russians, the British and the Dutch made attempts to find the shortest routes from Europe to the countries of the East (China and India). As a result of the voyage of Willem Barents at the end of the 16th century. a map of the western part of the ocean was drawn up.

The Great Northern Expedition (1733-1743) laid the foundation for the systematic study of the ocean shores. Its participants accomplished a scientific feat - they passed and put on the map the coast from the mouth of the Pechora to the Bering Strait.

The first information about the nature of the circumpolar regions of the ocean was collected at the end of the 19th century. during the drift of the Fram by F. Nansen and the voyage to the Pole at the beginning of the 20th century. G. Sedov on the schooner “St. Foca.

The possibility of passing through the ocean in one navigation was proven in 1932 by the expedition of the icebreaker Sibiryakov. Members of this expedition, led by O. Yu. Schmidt, measured the depths, measured the thickness of the ice, and observed the weather.

In our country, new methods for studying this ocean have been developed. In 1937, the first polar station "North Pole" (SP-1) was organized on a drifting ice floe. Four polar explorers led by ID Papanin made a heroic drift on an ice floe from the North Pole to the Greenland Sea.

Airplanes are now being used to study the ocean, landing on ice floes and making one-time observations. Images from space provide information about changes in the state of the atmosphere over the ocean, about the movement of ice.

As a result of all these studies, a large amount of material has been accumulated on the nature of the Arctic Ocean: on the climate, the organic world; the structure of the bottom topography was specified, and near-bottom currents were studied.

Many secrets of the nature of the Arctic Ocean are already known, but much remains to be revealed to future generations, including, perhaps, some of you.

The bottom relief has a complex structure. The central part of the ocean is crossed by mountain ranges and deep faults. Between the ridges lie deep depressions and basins. A characteristic feature of the ocean is a large shelf, which makes up more than a third of the area of ​​the ocean floor.

Climatic features are determined by the polar position of the ocean. It is dominated by arctic air masses. Fog is frequent in summer. The air masses of the Arctic are much warmer than the air masses that form over the Antarctic. The reason for this is the reserve of heat in the waters of the Arctic Ocean, which is constantly replenished with the warmth of the waters of the Atlantic and, to a lesser extent, the Pacific Ocean. Thus, oddly enough, the Arctic Ocean does not cool, but significantly warms up vast expanses of land in the Northern Hemisphere, especially during the winter months.

Under the influence of western and southwestern winds from the North Atlantic, a powerful flow of warm waters of the North Atlantic Current enters the Arctic Ocean. Along the coasts of Eurasia, waters move from west to east. Across the ocean, from the Bering Strait to Greenland, waters move in the opposite direction - from east to west.

The most characteristic feature of the nature of this ocean is the presence of ice. Their formation is associated with low temperature and relatively low salinity of surface water masses, which are desalinated by a large amount of river water flowing from the continents.

The removal of ice to other oceans is difficult. Therefore, multi-year ice 2-4 m thick and more prevails here. Winds and currents cause the movement and compression of ice, the formation of hummocks.

The bulk of organisms in the ocean are algae that can live in cold water and even on ice. The organic world is rich only in the Atlantic region and on the shelf near the mouths of rivers. Plankton is formed here, algae grow at the bottom, fish (cod, saffron cod, halibut) live. Whales, seals, walruses live in the ocean. Polar bears live in the Arctic, seabirds leading a colonial lifestyle and living on the shores. The entire population of the giant "bird colonies" feeds in the ocean.

There are two natural belts in the Arctic Ocean. The boundary of the polar (Arctic) belt in the south roughly coincides with the edge of the continental shelf. This deepest and harshest part of the ocean is covered with drifting ice. In summer, ice floes are covered with a layer of melt water. This belt is unsuitable for the life of organisms.

The part of the ocean adjacent to the land belongs to the subpolar (subarctic) belt. Basically, these are the seas of the Arctic Ocean. Nature is not so harsh here. In summer, water off the coast is free of ice, heavily desalinated by rivers. The warm waters penetrating here from the Atlantic create conditions for the development of plankton, which fish feed on.

Types of economic activity in the ocean. The Arctic Ocean is of exceptional importance for the countries whose shores are washed by its waters. The harsh nature of the ocean makes it difficult to find minerals in it. But deposits of oil and natural gas have already been explored on the shelf of the Kara and Barents Seas, off the coast of Alaska and Canada.

The biological wealth of the ocean is small. In the Atlantic region, fish are caught and algae are harvested, and seals are hunted. Whale hunting in the ocean is strictly limited.

Polar ice blocks and icebergs drift in the ocean, and even in drinks the ice never sinks to the bottom. It can be concluded that ice does not sink in water. Why? If you think about it, this question might seem a little strange, because ice is solid and - intuitively - should be heavier than liquid. While this statement is true for most substances, water is the exception to the rule. Water and ice are distinguished by hydrogen bonds, which make ice lighter in the solid state than when it is in the liquid state.

Scientific question: why ice does not sink in water

Imagine that we are in a lesson called "The World Around" in 3rd grade. “Why doesn’t ice sink in water?” the teacher asks the children. And the kids, not having deep knowledge in physics, begin to reason. "Perhaps it's magic?" says one of the children.

Indeed, the ice is extremely unusual. There are practically no other natural substances that, in the solid state, could float on the surface of a liquid. This is one of the properties that makes water such an unusual substance and, to be honest, it is this that changes the path of planetary evolution.

There are some planets that contain huge amounts of liquid hydrocarbons such as ammonia - however, when they freeze, this material sinks to the bottom. The reason why ice does not sink in water is that when water freezes, it expands, and with it, its density decreases. Interestingly, the expansion of ice can break rocks - the process of glaciation of water is so unusual.

Scientifically speaking, the freezing process sets up rapid cycles of weathering and certain chemicals released at the surface are capable of dissolving minerals. In general, there are processes and possibilities associated with the freezing of water that the physical properties of other liquids do not imply.

Density of ice and water

So the answer to the question of why ice doesn't sink in water, but floats on the surface, is that it has a lower density than liquid—but that's a first-level answer. To better understand, you need to know why ice has low density, why things float in the first place, how density leads to floating.

Recall the Greek genius Archimedes, who found out that after immersing a certain object in water, the volume of water increases by a number equal to the volume of the immersed object. In other words, if you place a deep dish on the surface of the water and then place a heavy object in it, the volume of water that will be poured into the dish will be exactly equal to the volume of the object. It doesn't matter if the object is fully or partially submerged.

Water properties

Water is an amazing substance that basically feeds life on earth, because every living organism needs it. One of the most important properties of water is that it has the highest density at 4°C. Thus, hot water or ice is less dense than cold water. Less dense substances float on top of denser substances.

For example, while preparing a salad, you may notice that the oil is on the surface of the vinegar - this can be explained by the fact that it has a lower density. The same law is also valid for explaining why ice does not sink in water, but sinks in gasoline and kerosene. It's just that these two substances have a lower density than ice. So, if you throw an inflatable ball into the pool, it will float on the surface, but if you throw a stone into the water, it will sink to the bottom.

What changes happen to water when it freezes

The reason ice doesn't sink in water is because of the hydrogen bonds that change when water freezes. As you know, water consists of one oxygen atom and two hydrogen atoms. They are attached by covalent bonds that are incredibly strong. However, the other type of bond that forms between different molecules, called a hydrogen bond, is weaker. These bonds form because the positively charged hydrogen atoms are attracted to the negatively charged oxygen atoms of neighboring water molecules.

When the water is warm, the molecules are very active, move around a lot, quickly form and break bonds with other water molecules. They have the energy to approach each other and move quickly. So why doesn't ice sink in water? Chemistry hides the answer.

Physical chemistry of ice

As the temperature of the water drops below 4 °C, the kinetic energy of the liquid decreases, so the molecules no longer move. They do not have the energy to move and are as easy as at high temperature to break and form bonds. Instead, they form more hydrogen bonds with other water molecules to form hexagonal lattice structures.

They form these structures to keep the negatively charged oxygen molecules apart. In the middle of the hexagons formed as a result of the activity of molecules, there is a lot of emptiness.

Ice sinks in water - reasons

Ice is actually 9% less dense than liquid water. Therefore, ice takes up more space than water. Practically, this makes sense because the ice expands. This is why it is not recommended to freeze a glass bottle of water - frozen water can create large cracks even in concrete. If you have a liter bottle of ice and a liter bottle of water, then an ice water bottle will be easier. The molecules are farther apart at this point than when the substance is in the liquid state. This is why ice does not sink in water.

As ice melts, the stable crystalline structure breaks down and becomes denser. When the water warms up to 4°C, it gains energy and the molecules move faster and farther. This is the reason why hot water takes up more space than cold water and floats on top of cold water - it has less density. Remember, when you are on the lake, while swimming, the top layer of water is always pleasant and warm, but when you put your feet down, you feel the coldness of the lower layer.

The significance of the process in the functioning of the planet

Despite the fact that the question "Why doesn't ice sink in water?" for grade 3, it is very important to understand why this process is happening and what it means for the planet. Thus, the buoyancy of ice has important implications for life on Earth. in cold places in winter - this allows fish and other aquatic animals to survive under the ice sheet. If the bottom were frozen, then there is a high probability that the entire lake could be frozen.

In such conditions, not a single organism would have survived.

If the density of ice were higher than the density of water, then the ice would sink in the oceans, and the ice caps, which would then be at the bottom, would not allow anyone to live there. The bottom of the ocean would be full of ice - and what would it all turn into? Among other things, polar ice is important because it reflects light and keeps planet Earth from getting too hot.

Young children very often ask interesting questions to adults, and they cannot always answer them right away. In order not to seem stupid to the child, we recommend that you familiarize yourself with a full and detailed, reasonable answer regarding the buoyancy of ice. It floats, not sinks. Why is this happening?

How to explain complex physical processes to a child?

The first thing that comes to mind is density. Yes, in fact, ice floats because it is less dense than. But how to explain to a child what density is? Nobody is obliged to tell him the school curriculum, but to reduce everything to the fact that it is quite real. Indeed, in fact, the same volume of water and ice has different weights. If we study the problem in more detail, then we can voice several more reasons, in addition to density.
not only because its reduced density prevents it from sinking lower. The reason is also that small air bubbles are frozen in the thickness of the ice. They also reduce the density, and therefore in general it turns out that the weight of the ice plate becomes even less. When the ice expands, it does not capture more air, but all those bubbles that are already inside this layer are there until the ice begins to melt or sublimate.

We conduct an experiment on the force of expansion of water

But how can you prove that ice is actually expanding? After all, water can also expand, how can you prove it in artificial conditions? You can conduct an interesting and very simple experiment. To do this, you need a plastic or cardboard cup and water. Its amount does not have to be large; you do not need to fill the glass to the brim. Also, ideally, you need a temperature of about -8 degrees or lower. If the temperature is too high, the experience will last unreasonably long.
So, the water is poured inside, we must wait for the ice to form. Since we have chosen the optimal temperature at which a small amount of liquid will turn into ice within two to three hours, you can safely go home and wait. You need to wait until all the water turns into ice. After some time, we look at the result. A deformed or ice-torn cup is guaranteed. At lower temperatures, the effects look more impressive, and the experiment itself takes less time.

Negative consequences

It turns out a simple experiment confirms that ice blocks really expand when the temperature decreases, and the volume of water easily increases when it freezes. As a rule, this feature brings a lot of problems to forgetful people: a bottle of champagne left on the balcony on New Year's Eve for a long time breaks due to ice exposure. Since the expansion force is very large, it cannot be influenced in any way. Well, as for the buoyancy of ice blocks, here you can not prove anything. The most curious can easily conduct a similar experience in spring or autumn on their own, trying to drown pieces of ice in a large puddle.