The sources of heat.
Text 1
What Heat is.
Heat is one of the most important forms of energy. When we think of heat, we usually think of how heat makes us feel. On a hot day, for example, it may make usfeel uncomfortable. But heat is far more important in our lives than simply how it may make us feel.
We must have a carefully controlled amount of heat to live. Our bodies use the food we eat to produce the heat that keeps our temperature at about 98.6 °F (37 °C). If our body temperature rises too far above normal or falls too far below normal we can die. In cold weather, we wear heavy clothes to hold in our body heat. During warm weather, we wear light clothes to let the un-needed heat escape.
No one knows how high temperatures may climb, but the temperature inside the hottest stars is many millions of degrees. The lowest possible temperature, called absolute zero, is -459.67 °F (-273.15 °C).
In our homes, we use heat in many ways. Heat warm our homes and cooks our food. It also provides hot water, dries the laundry, and makes electric light bulb give off light
In industry, the uses for heat are almost endless. Heat is used to separate metals from their ores and to refine crude oil. It is used to melt, shape, cut, coat, and harden metals and to join metals together. Heat is also used to make or process foods, glass, paper, textiles, and many other products.
Heat also runs our machinery. The heat from burning fuels in engines provides the power to move airplanes, automobiles, rockets, and ships. Heat causes the wheels of giant turbines to spin, driving generators that produceelectricity. Electricity provides light and furnishes power to run all kinds of equipment—from electric pencil sharpeners to electric trains.
This article discusses where heat comes from and what heat is, how it travels, and what it does. The article also describes how we have put heat to work and discoveries we have made about heat. Anything that gives off heat is a source of heat. The heat that we use or that affects life and events on the earth comes from six main sources. They are (1) the sun, (2) the earth, (3) chemical reactions, (4) nuclear energy, (5) friction, and (6) electricity.
We control some of these sources, and others we do not. We use the sources we control, such as electricity andnuclear energy, to heat buildings and do other work. But the sources we do not control also benefit us. For example, the sun provides the heat and light that make life possible. All sources of heat, even those that we normally control, can do great damage if they get out of control. For example, fires, which are chemical reactions, destroy much property every year.
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1.Study the following words:
un-needed, laundry, light bulb,crude oil, to spin, property, pencil sharpeners,
driving generators, endless, provide, to melt, earth
2. Complete the sentences with appropriate words from the text:
a) ….. warm our homes and cooks our food.
b)….. is used to separate metals from their ores and to refine crude oil.
c) Heat causes the wheels of giant turbines to spin, driving generators that produce……….
d) ….. provides the heat and light that make life possible.
e) The heat from burning … in engines provides the power to move airplanes, automobiles, rockets, and ships
3. Give the English definitions of the following words:
Heat, laundry, fuel, wheel, friction
4. Put questions to the following sentences:
a) Heat is one of the most important forms of energy.
b) Electricity provides light and furnishes power to run all kinds of equipment—from electric pencil sharpeners to electric trains.
c) Heat is also used to make or process foods, glass, paper, textiles, and many other products.
d) The heat that we use or that affects life and events on the earth comes from six main sources.
Text 2
The sources of heat.
The sun is our most important source of heat. If the sun should ever cool, the earth would become cold and lifeless. Only a tiny fraction of the heat produced in the sun strikes the earth. Yet it is enough to keep us and all other organisms on the earth alive.
The sun's heat is absorbed by the seas, the ground, plants, and the atmosphere. Large amounts of heat can be collected by using such devices as large solar furnaces. These furnaces have mirrors that reflect the sun's light from a wide area onto one spot Some solar furnaces can generate enough heat to melt steel. Smaller ones can gather enough heat to cook food.
The earth itself contains much heat deep inside, when a volcano devices, some of this heat escapes to the surface. The lava from a volcano is rock melted by the deep within the earth. Some of the earth's heat also escapes in geysers. These springs shoot forth boiling water that has been heated by hot rocks within the earth. People have begun to use the earth's heat to generate electricity, heat houses, and do other work..
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Chemical reactions can produce heat in a number of ways. A chemical reaction in which a substance combines with oxygen is called oxidation. Rapid oxidation produces heat fast enough to cause a flame. When coal, wood, natural gas, or any other fuel burns, substances in the fuel combine with oxygen in the air to form other compounds. This chemical reaction, which is known as combustion produces heat and fire. People use fire in many ways. Fire in a gas stove produces heat to cook food. Coal, oil, or gas fires in furnaces and boilers heat buildings. Fire heats metals red-hot so that they can be shaped into a variety of forms. Special cutting torches can produce flames hot enough to cut through metal.
Another example of combustion is the burning of gasoline in the cylinders of an automobile engine. This process produces heat that causes the gases in the cylinders to expand and move parts that make the engine work..
The rusting of iron is also an example of oxidation. Unlike fire, however, rusting occurs so slowly that little heat and no flames are produced.
The mixing of certain kinds of chemicals also produces heat. For example, if sulfuric acid and water are combined, the mixture becomes boiling hot
In all living things, food is changed into heat—as well as energy and living tissue —by the process of metabolism. Metabolism is a complicated series of chemical reactions carried out by living cells.
1.Study the following words:
Lifeless, tiny fraction, device, substance, combustion, flame, rusting, torches,
sulfuric acid, earth complicated, occur
2. Complete the sentences with appropriate words from the text:
1. ….. is a complicated series of chemical reactions carried out by living cells.
2. If the sun should ever cool, …. would become cold and lifeless.
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3. This process …. heat that causes the gases in the cylinders to expand and move parts that make the engine work.
4. The rusting of iron is also an example of ….
5. …. heats metals red-hot so that they can be shaped into a variety of forms
3. Define the part of the speech of the following words:
Oxidation, electricity, acid, compound, rapid, mixture, mixing, cells, carried,. unlike, boiling, tissue
4. Discuss the questions:
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