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. Fo r 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.

Lesson 2.

Part A.

ability	здібність, здатність
acceptable	прийнятний
accurate	точний, правильний
amount	кількість, загальна сума
appear	з’являтись, здаватись
associate	тісно пов’язаний, сполучати
assume	припускати, вважати, набирати
average	середній, звичайний
capable	здатний, здібний
carefully	ретельно
cause	причина, підстава, спричиняти
cellar	льох, підвал
certainly	звичайно, напевно
change	зміна, переміна
consider	розглядати, обдумувати
contemporary	сучасний
convert	перетворювати
create	творити, утворювати
crucible	критичний, вирішальний
define	визначати, окреслювати
definite	визначений, точний
depend	залишати, покластися
destroy	руйнувати
determine	визначати, примушувати
due to	завдяки
energy	енергія
equal	рівний
exist	існувати
expect	сподіватися, чекати
explain	пояснювати
extremely	вкрай
fluid	рідкий, текучий, рідина
forget	забувати
friction	тертя
furnace	піч, топка
furthermore	до того ж, крім того
gain	одержувати, заробляти
grain	гроно
heat	теплота
hence	віднині
however	проте, незважаючи на
increase	зростати, збільшувати
indicate	вказувати, означати
internal	внутрішній
lake	озеро
mean	засіб, спосіб
measure	міра, захід
melt	розчинятися, танути
mercury	ртуть
motion	рух
object	предмет, об’єкт, мета
observation	спостереження
perform	виконувати, здійснювати
phenomenon	явище
prove	доводити
random	випадковий
remain	залишатися
require	вимагати, потребувати
rise	піднімати, зростати, збільшуватись
sensation	почуття, відчуття
state	стан, становище, заявляти
substance	речовина, матерія
supply	постачання, постачати
suppose	гадати, вважати
surrounding	середовище, оточення
term	період, строк, термін
transmit	передавати
volume	том, кількість, ємність
weight	вага, гиря

Exercise 1. Read and translate the text.

What is Heat?

When heat, a form of energy, is supplied to a substance, we expect it to produce a rise of temperature. In other words, heat usually causes an increase in the average kinetic energy of the random motion of the molecules of which the substance is made up. However, heat may also produce a change of state without any temperature change.

Today heat is known to be a form of energy. But about a century ago heat was considered to be a kind of a weightless substance which was neither created, nor destroyed. This substance called "caloric" was believed to pass from a hotter body to a colder one, eventually both of them coming to the same temperature. To explain that phenomenon was easy: a hot body, it was supposed, contains more of the heat fluid, i.e. caloric, than a cold one; and this fluid flows from hot to cold. Again, people knew that it takes more caloric to raise the temperature of a pound of water 10⁰ than a pound of iron. They naturally supposed water to have higher caloric content than the iron. In fact, the caloric theory of heat as it was called accounted for almost everything that was known about heat at that time, except one important phenomenon, namely: the production of heat due to friction. However, numerous laboratory experiments demonstrated that each time when mechanical energy was expended as a result of friction, a corresponding amount of heat was produced.

In spite of that inability to explain the production of heat by friction, the caloric theory of heat seemed to be the only acceptable theory.

Great scientist and poet Lomonosov was among the first to find and state that heat phenomena were due to the motion of molecules. That statement of his resulted from many carefully performed laboratory experiments, from study and observation.

Lomonosov's theory laid the foundation for the present day molecular-kinetic theory of heat. As was often the case he left his contemporaries far behind and his statement was finally proved long after his death. The caloric theory of heat is known to have existed almost up to the middle of the 19th century.

The unit of heat is called a therm or a calorie; the latter term appears to come from the Latin word "calor" which means heat.

A calorie is defined as the amount of heat required at a pressure of one atmosphere to raise the temperature of onegram of water one degree Centigrade. (We know the gram to be a metric weight equal to 15.432 grains of the English system of weights).

One should not think that the very amount of heat which will raise the temperature of one gram of water from 0 to 1⁰ C will also raise the temperature of the same mass of water from, say, 60 to 61⁰ C. Experiments have shown that the quantities of heat to be required in these two cases are slightly different. Hence, the true calorie is defined as that quantity of heat which will raise the temperature of 1 gr of water from 19.5 to 20.5⁰C.