Text № 2. Energy

In the language of science energy is the ability to do work. There are various forms of energy, such as: heat, mechani­cal, electrical, chemical, atomic and so on. One might also mention the two kinds of mechanical energy — potential and kinetic, potential energy being the energy of position while kinetic energy is the energy of motion. It is well known that one form of energy can be changed into another.

A waterfall may serve as an example. Water is falling from its raised position, energy changes from potential to kinet­ic energy. The energy of falling water is generally used to turn the turbines of hydroelectric stations. The turbines in their turn arrive the electric generators, the latter produc­ing electric energy. Thus, the mechanical energy of falling water is turned into electric energy. The electric energy, in its turn, may be transformed into any other necessary form.

When an object losels Its potential energy, that energy is turned into kinetic energy. Thus, in the above-mentioned example when water is falling from its raised -position, it certainty loses its potential energy, that energy changing into kinetic energy (Fig. 1).

Fig. 1. Examples of kinetic energy.

We have already seen that energy of some kind must be employed to generate the electric current. Generally speaking, the sources of energy usually employed to produce current are either chemical, as in the battery, or mechanical, as in the electromagnetic generator. Chemical sources of current having a limited application the great quantities of electric energy generated today come from various forms of mechan­ical energy.

Rising standards of modern civilization and growing indus­trial application of the electric current result in an increas­ing need of energy. Every year we need more and more energy. We need it to do a lot of useful things that are done by electricity.

However, the energy sources of the world are decreasing at the same time as the energy needs of the world are increasing. These needs will continue to grow as more motors and melted metals are used in industry and more electric current is employed in everyday life. As a result, it is necessary to find new sources of energy.

The sun is an unlimited source of energy. However, at present, only a little part of solar energy is being used di­rectly. How can we employ solar energy directly to produce useful energy? This is a question which has interested scien­tists and inventors for a long time. Lavoisier and other great scientists of the past melted metals with the help of solar furnaces. Today, solar furnaces illustrate just one of the numerous ways to harness the sun. Using semiconductors, scientists, for example, have transformed solar energy into electric energy.

Exercise 10. Write down into your vocabulary all new words and word combinations and find their translations and transcriptions.

Exercise 11. Translate the following sentences paying attention to the absolute participle construction:

1. An object losing its potential energy, that energy is turned into kinetic energy. 2. Water falling from its raised position, energy is changed from potential to kinetic energy. 3. My friend was reading an English article, his brother watching television. 4. Electrical devices find a wide appli­cation in every house, a refrigerator being one of them. 5. There being a hydroelectric station at the waterfall, the energy of the falling water is used to drive the turbines. 6. The energy sources of the world decreasing, the scientists must find new sources of energy. 7. There are different sources of energy, the sun being an unlimited source of all forms of energy. 8. In­dustrial applications of energy increasing, more and more energy is needed every year:

Exercise 12. Give short answers to the following questions:

1. Can one form of energy be changed into another form? 2. Does a generator produce mechanical energy? 3. Is the sun an unlimited source of energy? 4. Can we employ solar energy directly? 5. Have scientists transformed solar energy into electric energy? 6. Is potential energy the energy of motion? 7. Do we need more and more electric energy every year? 8. Are there various forms of energy? 9. Do you use electric energy every day? 10. Can the energy of falling water be used to drive turbines? 11. Is kinetic energy the energy of posi­tion?

Exercise 13. State the energy change that takes place in each of the following devices:

Model: The motor changes electrical energy into mechan­ical energy.

1. generator, 2. lamp, 3. battery, 4. washing machine, 5. electric furnace, 6. vacuum cleaner, 7. semiconductor.

Exercise 14. Prepare a project on this theme.

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