Active Words and Expressions

to cause, certain, collision, compression, conduction, ex­pansion, to expect, to explain, friction, molecule, not at all, on the contrary, to place, quantity, to take place, term

_Exercises

/. Translate the following sentences using the infinitive constructions:

I. Мы знаем, что тепловая энергия — это энергия моле- кулярного движения. 2. Известно, что молекулы движутся в различных направлениях. 3. В течение долгого времени считали, что тепло — это невесомое вещество. 4. Говорят, что молекулы воды движутся быстрее, когда ее нагревают. 5. Считают, что молекулы холодного вещества движутся медленнее. 6. Известно, что при нагревании тела расширя- ются. 7. Студенты, наверное, понимают разницу между постоянным и переменным током.

II. Find the infinitive in the text and define its function.

III. Translate the following questions and answer them:

1. Что такое тепло? 2. Почему предполагали, что тепло — это невесомое вещество? 3. Могли ли люди наблюдать некоторые тепловые эффекты? 4. Что происходит благода­ря трению и сжатию? 5. Какие тепловые явления (pheno­mena) установил Ломоносов? 6. Из чего состоит вещество? 7. Как называются мельчайшие частицы вещества? 8. Что происходит, когда тело нагревается? 9. Существует ли за­метная разница температур между холодным и горячим телом? 10. Какой прибор используется для измерения тем­пературы?

IV. Translate the following sentences and define the func- tion of the word one.

1. Observations show that a hot object radiates more heat than a cold one. 2. One can say that heat is one form of ener-

gy. 3. This problem is more complicated than the one you have told me about. 4. The direct current is the flow of elec­trons in one direction. 5. Heat is known to pass from a hotter body to a colder one. 6. There are many hydropower stations in the USSR, the one on the Angara being the largest.

^{V. Arrange the following words in pairs of:}

(a)	antonyms:	^(b) synonyms:
at rest	positive	to employ	to move
solid	right	to make	similar
fast	the last	to travel	various
useful	decrease	different	fluid
^charge	liquid	like	to do
hot	in motion	to receive	^to^get
dark	invaluable	^liquid	to use
negative	slow
the first	useless
increase	discharge
^wrong	cold
valuable	light

VI. (a) Form verbs from the following nouns:

increase, weight, statement, movement, difference, com­pression, collision, flow, application, requirement, knowl­edge, education, expansion

(b) Use the verbs formed in sentences of your own.

VII. What do the following words mean in addition to their meaning and use in the previous texts:

current, table, iron, power, needle, pressure, wire, state

VIII. Translate the following sentences, paying attention to the words in bold type:

1. Static charges are known to be at rest. 2. Alternating current changes its direction many times a second. 3. We know the electric charges to be positive and negative. 4. Some liquids are known to conduct current without any changes to themselves. 5. On the contrary the electrolytes are known to change greatly when the current flows through them. 6. One can charge dissimilar objects by rubbing them.

IX. Make up 4 sentences using the infinitive constructions according to the models given below:

Models: 1. I heard my friend speak over the radio.

2. My teacher wants me to speak English well.

X. Speak on the work of the following scientists using the words given below:

Franklin: to prove, unlike, charge, to rub, dissimilar, object, rubber, negative, glass, positive.

Volta: continuous current, to produce, the first, unit, electric, pressure, volt, voltaic pile.

Lornonosov: to state, heat, phenomena, molecular, motion, atomic, theory, law, conservation, matter.

XI. Read and retell the following story:

_{HEAT AND COLD}

At a physics lesson the teacher asked the children about the effects of heat and cold on the body.

"Heat makes things bigger and cold makes things smaller," answered a clever boy.

"Quite right," said the teacher. "Can you give an exam­ple?"

"In summer, when it is hot, the days are longer, but in winter, when it is cold, the days are shorter," answered the clever boy.

LESSON THIRTEEN

THE INFINITIVE