In which kettle will water cool faster

Physics lesson in grade 8 “Physics over a cup of tea

Purpose: repetition of the topic “thermal phenomena”, consolidating the skills of applying the acquired knowledge in everyday practice, the development of observation and interest in the subject.

Equipment: electric carrier; teapot; glasses with cup holders, cards. Tasks, tests, multimedia installation

Organizing time. 2. The introductory word of the teacher. 3. Work in groups. 4. Experiments for a cup of tea. 5.Frontal conversation. 6.Work on Perov’s picture “Tea Party in Mytishchi”. 7. Physmine. Eight. Working with a schedule evaporation and condensation. Nine. Fixing (test). Ten. Homework. Eleven. The result of the lesson. 12. Reflection.

In the class we place the tables and sit the students in groups. Tables can be covered with a tablecloth, put cups, and in the center. A dish with sweets and cookies

Teacher: Hello. Today we have an extraordinary lesson. It’s about tea. Tea drink in many countries of the world. There are their national characteristics of tea drinking, and even tea ceremonies. Many do not even suspect that tea. This most popular drink in the world for about 5,000 years. The history of the birth of tea is rooted in ancient times, covered with old legends and myths.

Tea appeared in Russia in 1638, when the Mongolian Altyn Khan sent 4 pounds of tea as a gift to Tsar Mikhail Fedorovich as a gift.

Our current tea party also has its own characteristics. This tea party is physical! We will try to combine pleasant with useful and repeat the features of thermal phenomena behind tea. What does the physicist have to do with tea? Well, let’s try to figure it out together. So, proceed to cooking tea.

Pour water into the kettle. What is boiling?

How much water should be poured into the kettle so that it does not spill through when boiling? (When heated, the water expands and spills over the edge.)

Teacher: In the meantime, the kettle boils, work in groups and discuss the proposed issues. Each team records all the physical phenomena that occur during the water heating within 5 minutes and explains these phenomena, and then in turn answer questions.

One. What phenomenon underlies water heating, because the heat is transmitted to the kettle from below, and water is a poor heat conductor.

(Answer: convection, energy is transferred by jets of fluid, due to this water heats up throughout the volume.)

We took such a beautiful, transparent kettle for cooking tea. But what do you think, which kettle, black or white, will take the mistress if she wants the water to be preserved hot for as long as possible and why?

(Answer: The black heated body radiates heat faster than white)

Why are a samovar or a kettle cover a lid?

(Answer: with the lid open, part of the molecules with large kinetic energy will fly away from the kettle, taking away energy with it, so the water will boil faster if you close the lid)

The question is why it is boiling before boiling, the water in the kettle begins to make noise? (Water adjacent to the bottom of the kettle turns into steam, which forms small bubbles. As lighter bubbles, these are replaced up, here the water is colder and the steam in the bubbles turns into water and the walls of the bubbles under pressure from the surrounding water are closed, slammed. From these numerous crackling and there is a noise that we hear before boiling.)

which, kettle, water, cool

The question at what temperature water will boil? (Answer: 100 0 s.)

The question is always water at the same temperature? Why it depends? (Answer: No, the boiling point depends on atmospheric pressure; and in the mountains at a height it is below t.To. There is below atmospheric pressure.

The question of what is a simple way to increase the boiling point of water in the kettle? (Answer: Increase the pressure above the surface of the water. To do this, tightly close the kettle with a lid, put the load on top, insert the cork into the nose.)

The question is in which kitchen appliances this method is used- increasing pressure over boiling liquid? (Answer: In the Skorovarkuki. Increased pressure is caused by an increase in boiling temperature.)

The question from the nose bursts out of the way, but the couples are invisible! What is it really?

(Answer: these are droplets of water in the air. Fog. Escaping from the nose of the kettle, he condenses in the cool air, forming the smallest droplets of water, and we see them.)

The question is why the handle of the samovar is made by plastic? (Plastic does not conduct heat well.

How to brew tea correctly? (Student’s message.)

It’s time to brew tea, yes to treat guests! The taste of tea depends on whether it is welded correctly. This means that tea must be brewed so that the substances that are part of the tea leaf are possible to go into the water in the possible amount. It is known that the taste of tea depends on the temperature at which it is welded. The higher the temperature at the time of the hotel, the tastier the tea. Therefore, in order for the internal walls of the teapot to have a higher temperature at the time of welding, it is recommended to rinse the kettle with boiling water before filling tea once or twice. Then less heat will “go” to its heating. Then cover the kettle with a napkin or towel so that the nose and lid are closed. This is necessary to preserve the aroma. It is impossible to cover the kettle with a heater, tea should not be praut, otherwise it will smell like a broom.

Please tell me the question, why is a hole in the cover of the teapot?

(Answer: If there were no holes, then steam would accumulate above the water, the pressure increased, under the influence of which the water would have poured out of the nose.)

You can pour tea into glasses. But an experienced mistress knows that before pouring tea into a glass so that he does not burst from hot water.

The question of what needs to be done and why? (Answer: put a metal spoon in a glass, it will take part of the heat, the water temperature will become lower, the thermal expansion of the internal walls will be less and the deformation will not be destructive, and then pour boiling water.)

Compare the speed of cooling tea in two different circles with the same masses of hot water.

Find out how the mass of water is spent in the same circles, on the speed of cooling.

3.Pour a little hot tea on a saucer and let it cool. Take a hot glass and overturn it in a saucer. After a short time, all the tea from the saucer will gather under a glass.

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MOBU “Nurminskaya secondary school”

The dependence of the water cooling temperature in the kettle

Theme of my project: The dependence of the water cooling temperature in the kettle on its shape

Problem: From grade 1, we study mathematics and all the time say that mathematics is used everywhere. At school, I see the use of mathematics in chemistry lessons (proportions), physics (work with formulas), geography (scale, calculation), technology (drawings and calculations), etc. D. And how mathematics is used in my everyday life?. I asked myself a question. I saw the answer to this question and applied when I went to the store, when I thought what grades would go out for a quarter. But I still have questions: how else mathematics is used for example in the kitchen? And since I really love hot tea, I decided to study the question of which kettle better retains the temperature of the water?

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The world of diversity of dummies in the modern world is very great. It is very difficult to make the right and economical option.

Target: Conduct a study and establish the dependence of the safety of the water temperature in the kettle on its shape. It is clear that the temperature of the water in the kettle depends on what material the kettle is made of. But this is physics. I decided to consider which form the kettle holds the temperature better (cylindrical, in the form of sphere, hemispheres or other. Forms). After the study, advise friends and loved ones what kind of kettle is better to have in the kitchen.

Calculate the surface area of ​​teapots of various shapes.

Conduct a poll by students “What shape is a kettle in your house”.

Create an advertising booklet for the right choice. Teapot

Hypothesis: It is better to hold the temperature of heating that kettle that is smaller than the surface area (teapots are made of one material and have the same volume of 500 ml)

I put forward the hypothesis immediately, relying on my life experience. As you all know, a hot drink in a saucer cools faster than in a glass, t. To. The larger the surface area, the faster the cooling. After that, it became clear to me what formulas I need to study and apply. Now a little about teapots.

But you know that teapots are of different types:

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Tapes for plates. It is usually a metal container with a handle, which is placed on the kitchen plate to heat water. Usually electric or gas. Less often for wood or coal. Even less often in the oven

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Hage kettle (Kostrovoy). Unlike the kettle for the stove, is designed to suspend the bonfire. And is usually used in marching conditions.

Electric kettle. Uses for heating an internal source of thermal energy (usually a heat element with a spiral), powered by electricity

Hinged teapot. Used to save space and is suspended on the wall. Through the filter, water enters it directly from the water supply. The tap is located at the bottom of the kettle, which allows you to completely empty the kettle. Looks like a flattened suspension samovar.

Custard. Dishes for pouring tea sheets (including in a tea bag) with hot or boiling water in order to make tea. Can be ceramic, earthenware, faor, metal, glass.

Tetsubin. A variety of Japanese cast.Iron teapot. Since when heated, iron enters water, water from such a kettle can be considered a food source of iron.

In a figurative sense, “teapots” are also called inexperienced people, beginners in some matter. This is from the 60s when the passion for mountaineering and skiing began. Beginners loved to pose for photographs resting one hand in the side, and taking the other a little to the side and putting ski sticks stuck in the ground on top. In shape it resembled a kettle. From climbers, the nickname migrated to motorists, and now to inexperienced PC users not least thanks to a series of books ” for dummies”. By the way, in the original this series is called for dummies. What actually translates as “for idiots”. Perhaps the Americans somehow react differently to such a definition, but in the Russian translation series they decided to replace this name with a milder.

I took the main information from the textbook “Geometry 10-11”, figured out the concepts of the sphere, cylinder, truncated cone and rectangular parallelepiped.

Ball. A body that consists of all points of space located at a distance, no more than a given point from this point.

Cylinder. A geometric body limited by a cylindrical surface and two parallel planes crossing it.

Frustum. A geometric body limited by a cylindrical surface and two parallel planes crossing it.

Rectangular parallelepiped

Rectangular parallelepiped. This is a voluminous figure that has six faces, and each of them is a rectangle

I chose these geometric bodies, t. To. Collar teapots most often have these forms. Then I studied the formulas of the volume and surface area of ​​these bodies, all the components included in them. All calculations were repelled from one number. Volume 300 ml. Having performed the necessary actions, having received the results of the surfaces of these bodies, he compared and concluded: it turns out that a small surface area has a ball!

How the teapot was invented?

The first electric kettle was born in the 19th century in Germany invention attributed it to a certain colonel Crompton, who came up with an electric heating element into a stand of an ordinary metal kettle for heating water.

The bottom line is that any model of electric kettle is striving to heat water to a temperature of 100 g. Depending on the power and volume of the device, it takes a different period of time for this process. The maximum water temperature can be 120-150 degrees.

How to boil water correctly and what temperature is needed to brew tea

One of the important stages to obtain a delicious, healthy and aromatic infusion is to obtain boiling water. But remember, the thrown water, as well as re.Boiled water. Dead water!

Water usually contains a lot of microscopic salts, and if it is crossed, then their concentration will increase. Boiling water should be young. If the water did not have time to boil, tea leaves will not turn around, do not fall to the bottom, but will swim on the surface. Tea will not brew and the aroma of tea will not open either. And each tea also has its own temperature requirements. Therefore, after the water boiled, If you need a temperature below than 100 degrees, it is allowed to cool. When there is no armometer for water at hand, they use the rule, water cools in about a temperature of 85 degrees in five minutes.

To get young boiling water, you need to monitor the water in the kettle. The treatise of the famous Lou Yu said that when the “crab eye” appears first. Small bubbles at the bottom and at the same time light clicking begins. This is the first stage of boiling water. Water temperature-approximately 70-80 s.

Then the bubbles increase, the crackling becomes more often and merges into a slight noise and the second short stage is called the “fish”. The temperature is about 80-85C.

Then “pearl threads” begin to rise along the walls of the teapot. A sort of threads of bubbles, the water begins to seethe, the noise changes a little and it becomes as if deaf. This is the third stage. It is she who is considered the most suitable for filling tea into the water (if you cook tea by Lu Yu) or removing water from the fire. The temperature is about 85-92s. Also, this stage is very short. This stage is called the “noise of the wind in the pines”. If you listen to the water at this moment, you will understand why. But since in order to catch it, we need to practice, we recommend that you shoot the kettle not the third stage.

When stormy waves go along the surface of the water. The so.Called “volumetric boil”. This is the fourth stage of brewing boiling water. The fourth stage of boiling water, according to Lu Yu, is not suitable for brewing tea. And the whole point is that the oxygen contained in water is lost, they leave the water with steam, from which the water changes the taste.

If the water is hard or not clean, then there will be no classic stages of boiling or they will be greased.

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The water boiled and we got young boiling water. Further, if you need to give water to cool. If we don’t remember what temperature we were recommended in the description for tea, then we adhere to the general rule:

The water temperature from 90 degrees to 95 is suitable for brewing black teas, such as Puer, completely fermented (these are red teas), as well as strongly fermented Ulunskaya.

The temperature of water from 80 to 90 degrees is brewed mainly poorly fermented Taiwanese Ulun teas.

Low water temperature, which is below 80 degrees, is suitable for green, white and yellow teas.

It is important to brew tea with the desired temperature, because if you brew delicate green or white tea with boiling water, then there will be no freshness, there will be no lightness, there will be no sweetness, there will be no rich aftertaste, but there will be a taste of bitterness and unpleasant astringency. Only properly brewed tea will give us amazing sensations, feelings of pleasant lightness, purity of thought and, finally, pleasant communication, if brewed not only for yourself.

What to boil water?

As you can see, in both cases we use glass. It is chemically inert and allows you to observe water.

Other materials:

Plastic (electric teapots). The most inappropriate option. Plastic is not inert chemically. In addition, it is worth avoiding teapots that prevent the formation of scale. The heating element will remain clean and shiny, but the water will remain rigid, and calcium enters the body and can provoke the formation of stones in the kidneys.

Iron (metal teapots for heating on fire). Not particularly suitable for boiling water option. Metal in one way or another is in contact with water, changing its taste. That is why it is better not to get rid of scale on the walls of metal teapots or use enameled dishes.

Fire-clay. The most canonical (based on old treatises about tea) option for boiling water. But also the rarest in a city apartment. Clay passes oxygen, enriches water, holds heat for a long time. And although through the clay walls you can’t see the stages of boiling water, by sounds made by such a kettle, you can easily determine what kind of boiling stage is located.

Russian phrases and expressions from which foreigners “breaks the brain

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The mind cannot understand Russia. I am sure that absolutely everything will agree with me! In fact, there are a lot of things that are inherent exclusively to the inhabitants of our country. I present to your attention a second selection of phrases and expressions that we use in speech often and without thinking. However, many foreigners can slightly “break the brain” from them.

How to understand this to an American? The person asked a question, you answered him with one sentence consisting of three. Each of which is already an answer that contradicts the other. And how the interlocutor understood? What?

I crossed the borsh because I went too far with salt.

What did you do with salt? I went too far with salt? But you just said that the borsch was pouring?

The kettle boils for a long time. The kettle does not boil for a long time.

Go explain to any foreigner that the phrases “a kettle boils for a long time” and “a kettle does not boil for a long time” mean the same. Their head will boil faster than the kettle.

Such combinations in the Russian language are not so few.

The kettle cools for a long time. The kettle does not cool for a long time.

The student solves the problem for a long time. The student does not solve the problem for a long time.

The sun comes in for a long time. The sun does not come in for a long time.

He decided to go for a long time. I did not dare to go for a long time.

The child falls asleep for a long time. The child does not fall asleep for a long time.

We decided to send to go buy a drink.

A proposal consisting of 5 verbs and nothing more. No commas. Even the most Russified Americans can cause bewilderment, at least with this phrase.

And how can they translate this proposal into English? And will they be able to?

How can this be understood at all to a person who has a native language. Not Russian?

Like a pig. Get drunk like a pig.

In the first case, a person eats too much food and does it ugly. In the second case, there is no need at all.

Keep your tail with a gun.

You and I understand what the phrase means. If you are asked to hold the tail with a gun, then you need to be on a check, careful. But what will be an American reaction?

Horror, how good I am.

Bus inscription: All hares. Goats!

What does it mean at all? Hare. This is a hare, but not a goat. Only a goat can be a goat, but not a hare most likely, this is exactly what a typical American will think, who does not know that the words hares and goats are a figurative meaning.

Study of the influence of the shape, color and size of the kettle on the speed of cooling water in it. Author: Bakhkhalov Vadim 8 and class

Nowadays, there are many teapots, different in shape, color and capacity. Choosing the right one is not so easy. Recently, special teapots have been advertised with ergonomic design, in which water boils faster, electricity consumption is smaller and water cools more slowly.

In physics lessons, we got acquainted with the types of heat transfer: thermal conductivity, convection, radiation. And we know that the dark body radiates stronger than white. The idea arose: whether the color plays the color in boiling and cooling of water. Ergonomic design is an advertising trick, or a mathematical pattern is taken into account here: that with a smaller surface there is less heat loss of heat.

I need to establish the dependence of boiling and cooling of water on color, size and volume in the kettle. To do this, you just need to take several different teapots, observe cooling water for a certain time and compare the results. I conducted experiments with seven teapots. In each of them I poured 1 liter of water, boiled and watched it cool. Measured the temperature thermometer after 1 minute. The measurement data entered into tables.

Measurement results and kettles used. Ŧ, in min 14 16 18 20 22 22 26 28 30 32 34 36 T. In ° C 72 70 68 66 64 63 61 60 59 57 56 56 1). Teaker B Raun. Black, 1.6 liters. Ŧ, in min 14 16 18 20 22 22 26 28 30 32 34 36 T. In ° C 72 70 68 66 64 63 61 60 59 57 56 56

2) Scarlett kettle. Blue with an ergonomic design of 1.8 liters. Ŧ, in mines 1 2 3 4 5 6 7 8 9 10 11 12 13 16 16 T. In ° C 84 82.5 81 80 79 78 76.5 75 74 73 72 71.5 71 70 68 ŧ, in min 18 20 22 22 22 26 28 30 32 34 36 38 40 42 44 T. In ° C 67 65.5 64 63 61.5 60 59 58 56 55 54.5 54 53.5

3) Scarlett kettle. White, 1.8 liters ŧ, in mines 0 1 2 3 4 5 6 7 8 9 10 11 12 13 16 16 T. In ° C 93 90 88 86 84 83 81 80 77.5 76 75 74 74 73 72 70 ŧ, in mines 18 20 22 22 22 28 30 32 34 T. In ° C 68 66 65 63 62 61 59 58 57

4) Tefal kettle. 1liter, white. Ŧ, in mines 0 1 2 3 4 5 6 7 8 9 10 T. In ° C 92 91 89 88 86 85 84 82 81 80 78 ŧ, in min 12 14 16 16 20 22 22 28 30 32 T. In ° C 76 74 72 70 68 66 64 62 60 58 56

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5) Braun teapot. 3 liters, white ŧ, in mines 0 1 2 3 4 5 6 7 8 9 10 T. In ° C 98 96 94 92 90 87 86 84 83 81 79 ŧ, in min 12 14 16 16 16 22 22 28 30 32 T. In ° C 76 74 72 70 65 65 64 63 59 57 I decided to conduct the same experience on the same kettle, but with an open cover. Ŧ, in mines 0 1 2 3 4 5 6 7 8 9 10 T. In ° C 93 89 85 83 80 78 76 75 73 71 70 ŧ, in min 12 14 16 18 T. In ° C 67 64 50 40

6) Philips kettle. Iron, 1.7 liters ŧ, in mines 1 2 3 4 5 6 7 8 9 10 T. In ° C 102 98 96 94 92 91 90 88 86 84 ŧ, in min 12 14 16 16 16 20 22 22 28 30 32 T. In ° C 83 8 1 79 76 74 72 70 68 66 64 62

The water cooled the longest in the iron teapot of Philips on the openest water in the open braun kettle and in the Tekta T EFAL (closed) on the basis of the experiments and the data obtained, I built graphs of water temperature about the time.

Graphs of water temperature in teapots from time.

Conclusion: teapots of different colors, shapes cool the same. A teapot with an ergonomic design was no exception. The next stage of research: I calculated how much energy is spent on boiling 1 liter of water in different teapots. The results of the measurement of electricity consumption and the cost of one boiling are entered into the table.

Teapot energy consumption cost Braun. Black, 3000 W 120 W/h 1.14 rubles Tefal, White, 2000-2200W 120 W/h 1.14 rubles Scarlett. Ergonomic design, 2000W 110 W/h 1.05 rubles, let the teapot boiled 5 times during the day, then the savings of ergonomic design will be 50 W/h per day. Savings per month: 1500 W/h = 1.5 kW/h. The cost of saved energy: 1.5 kW/h 0.95 = 1.43 Thus, using the advertised teapot of ergonomic design, the family saves 1,43 kopecia per month. At today’s prices, this is very insignificant. Even if we assume that the kettle was included more often, the savings result in 3 rubles. This is also imperceptible. Thus, when using different teapots, the savings are small and the electricity consumption is one.

I conducted research, studying the pattern of boiling and cooling of water in various teapots (color and shape) established: 1) that color and shape do not affect this temperature interval (20 ÷ 100) on the speed of cooling water. 2) ergonomic design is an advertisement, since the speed of cooling is the same with an ordinary kettle (black or white) 3) saving in money, I counted 1.5 rubles, which is very slight. 4) the open cover had a significant impact on the speed of cooling. 5). The water boils in all teapots the same, the difference is 10. 15 seconds. Conclusion:

In this temperature range, convection flows have a significant effect on the speed of cooling, not radiation. And convection on color and form does not depend. Ergonomic design. Advertising trick. Color and shape is design. Therefore, regardless of capacity, color and shape, you can choose the kettle that you like, there will be no difference. Conclusion:

How much a kettle cools to 80 degrees?

80 degrees. 1 minute; 70 degrees. 8 minutes; 60 degrees. 16 minutes; 50 degrees. 25 minutes.

The exact temperature at which hot water becomes boiling water is not determined (the boiling point of water varies with height), but in science and the preparation of coffee, a range of 90-95 ° C is usually used. Boiling water is accompanied by abundant discharge of steam, while free molecules are released from the composition of the liquid.

which, kettle, water, cool

Test with answers: “Types of heat transfer”

One sausage is covered with soot, the other is whitewashed with lime. They are filled with hot water of the same temperature. In which flask water cooled faster: a) in the white.White flask b) in both flasks, the temperature of the water will decrease equally B) in the smoked flask

Когда белье на открытом балконе высохнет быстрее: а) в ветреный день б) в безветренный день в) во время дождя

In which of the listed heat transfer bodies occurs mainly by thermal conductivity: a) air b) water c) brick

Convection is the process: a) penetration as a result of the thermal motion of the atoms of one body into the intervals between atoms of another body b) the heat transfer to the streams of substance c) the emission and absorption of thermal electromagnetic radiation without direct contact between the bodies

What substance has the smallest thermal conductivity: a) aluminum b) lead c) air

Water boils in a burning gas burner on a burning gas burner. Which of the processes listed below is made by the smallest contribution to the boiling process: a) diffusion b) evaporation inside the air bubbles when boiling B) convection of water layers inside the kettle

which, kettle, water, cool

What substance has the smallest thermal conductivity: a) lead b) aluminum c) fur

One type of heat transfer: a) thermal conductivity b) thermal conductivity c) heat resistance

What substance has the greatest thermal conductivity: a) aluminum b) air c) fur

One type of heat transfer: a) greenhouse radiation b) thermal radiation c) heat production

What substance has the greatest thermal conductivity: a) lead b) fur c) air

On which of the heat transfer methods the heating of solid bodies is based: a) radiation b) convection c) thermal conductivity

So that fruit trees do not freeze, their trunk circles for the winter are covered with sawdust. Sawdust possess thermal conductivity: a) bad b) good c) unknown what

What type of heat transfer is accompanied by the transfer of matter: a) thermal conductivity b) convection c) radiation

In what method of heat transfer heat is heated in a pan on a gas stove: a) thermal conductivity b) by radiation c) convection

Which of the substances listed below has the greatest thermal conductivity: a) fur b) steel c) wood

Will the body temperature change if it absorbs the radiation energy more than emits: a) the body cools b) the body temperature does not change c) the body will heat up

Which of the substances listed below has the lowest thermal conductivity: a) steel b) sawdust c) lead

In what color do the outer surfaces of the aircraft, artificial satellites of the Earth, balloons be painted to avoid overheating: a) in light, silver color b) in dark color B) red in red

What is a possible method of heat transfer between the bodies separated by the airless space: a) thermal conductivity b) radiation c) convection

What substance has the smallest thermal conductivity: a) cast iron b) silver c) paper

Metal handle and wooden door will seem to the touch equally heated at temperatures: a) below body temperature b) equal to body temperature c) above body temperature

What substance has the smallest thermal conductivity: a) silver b) cast iron c) straw

What happens to the temperature of the body if it absorbs as much energy as it radiates: a) the body heats b) body temperature does not change c) the body cools

What substance has the greatest thermal conductivity: a) silver b) straw c) paper

On what heat transfer method is based on water heating: a) thermal conductivity b) radiation c) convection

What substance has the greatest thermal conductivity: a) cast iron b) paper c) straw

Double frames are protected from the cold, because the air between them has thermal conductivity: a) good b) bad c) does not have thermal conductivity

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