Part c.

Exercise 1. Read and translate the text.

Law of Conservation and Transformation of Energy.

If a given amount of energy is put into a machine, precisely that very amount will be developed, neither mo­re nor less. This law is universally known and all physi­cal phenomena follow it.

We have seen a number of cases where one kind of energy has actually been transformed into another. Whe­never energy in one form is expended, an equal amount of energy in some other form takes its place.

We have different units in which various forms of ener­gy are measured but after the conversion of work into heat, or chemical energy into work or into electrical energy the actual amount of energy is the same as before the change. In other words, when energy is spent there is still as much energy as before. This fact which is one of the fundamen­tals of physics is known as the Law of the Conservation and Transformation of Energy.

According to the aforesaid law energy can neither be created, nor destroyed although its form can be changed. All the transformations, the endless number of chemical changes that are always taking place are only changing energy from one form into another without affecting the total. Though it is quite true that energy cannot disappear, it is an unpleasant fact that it very easily turns into a use­less form.

All machines and appliances that have ever been built and rebuilt by man since prehistoric times have some ener­gy "loss", that energy being converted into useless heat due to friction. Hence, the useful work to be done by a machine is less than the total work performed by it. The energy lost for work is not really lost but only converted into another form. No machine can be made completely frictionless but the undesirable effects of friction can be reduced, of cour­se. Friction reducing the efficiency of our machines, one might think that it is always undesirable. However, it would be a misconception of that phenomenon, since but for friction it would be impossible to control the motion of any machine.

We have already noted that we always lose some useful energy when machines are used. Why then do we use them in spite of that disadvantage? We often use machines to transfer energy from one place to another and to transform energy. The dynamo, for example, changes mechanical energy into electric energy. The energy of water is also transformed into electric energy by means of hydraulic turbines.

Wherever there is motion, we see the process of conver­sion of mechanical energy into heat. Is it possible to re­convert heat into mechanical energy? Yes, undoubtedly, it is. Besides, just as mechanical energy and heat can be interconverted, so can heat and chemical energy be converted one into another.

Exercise 2. Answer the following questions.

1. What laws are discussed in this article?

2. Can energy be created and destroyed?

3. Is energy easily turned into a useless form?

4. Why is energy converted into useless heat?

5. What reduces the efficiency of machines?

6. Is friction always undesirable?

7. What machines changes mechanical energy into electric energy?

8. By what means is the energy of water transformed into electric energy?

9. When is mechanical energy converted into heat?

10. Can chemical energy be converted into heat?

Exercise 3. Give different Ukrainian meanings of the following words:

only, power, case, for, but, mean, since, one, very, still, as.

Exercise 4. Form new words, using, prefixes and suffixes.

End, appear, peasant, history, uses, vary, real, convert, friction, advantage,

Exercise 5. Translate the following sentences, paying attention to the words in bold type.

1. Steel used for making different parts of machines.

2. For 2 thousand years it was believed that all heavy objects feel faster than light ones. For Aristotle had stated that it was so.

3. The engineers saw that all the devices but one were operating in the proper way.

4. There is but one way for solving the problem but is will take too much time.

5. The metric system is adopted by all countries of the world but England and America.

6. One cannot but mention here that the first work on electricity was written by Lomonosov.

Exercise 6. Speak about the main idea (ideas) of the text.

Exercise 7. Write out keywords and phrases. Make up a short summary of the text.