Part c.

Exercise 1. Read and translate the text.

Internal Energy.

A thermometer tells you the temperature of a substance but not the amount of internal energy in it. We know a cup of water at boiling point to be hotter than the water in a lake, however, the lake contains much more energy than the cup does. A large piece of ice will melt if thrown into the lake but only a small piece of ice could be melted by the hot water in the cup. The lake can give up more energy than the cup of water, even though the lake is at a much lower temperature. Thus, to measure the amount of energy given to an object, one must do more than simply determine its temperature change.

Here is another example to be considered. Let us take a small cup of boiling water and a large container also full of boiling water.

Both of them, certainly, have the same temperature. Thermometers would show the same reading for both the water in the cup and that in the container. They do not, however, contain the same amount of energy. It takes much more heat to make the water boil in the large container than it is required to boil the small cup of water. Again we see that the temperature of an object does not indicate the amount of energy to be contained in that object.

The amount of energy in a given body appears to depend on the nature of the body as well as on its size and temperature. Two bodies of equal weight but of dissimilar materials may have the same temperature but contain quite different amounts of energy. A 100-gram ball of iron at a given temperature is known to contain a smaller quantity of energy than does a 100-gram aluminium ball at the same temperature. „But what does the expression the same temperature really mean?” – one might ask. Two bodies are assumed to have the same temperature if when one of these bodies is placed in contact with the other one neither will transfer heat to the other.

A heated metal ball to be placed in contact with a piece of ice will transmit its heat to the piece of ice, that heat melting the ice. The fact that the metal ball loses heat shows that the two materials are not at the same temperature. If this metal ball is placed in the crucible of an electric furnace, the ball will gain sufficient heat from the crucible to make it melt. It shows that the crucible is much hotter than the ball. In any process where heat is transferred the body which is at a lower temperature is the one that gains heat.

To know the quantity of energy present in a body is very important, therefore, we shall shortly see what units are to be used for measuring the quantity of heat and how one can find the amount of energy which a given body contains.

Exercise 2. Answer the following questions.

1. What does a thermometer tell us?

2. Does a thermometer tell you the amount of internal energy in a substance?

3. Why can the lake give up more energy than a cup of boiling water?

4. What does the amount of energy in a given body depend on?

5. What will happen to a piece of ice if it is placed in contract with heated metal ball?

6. Does the temperature of an object indicate the amount of energy contained in it?

7. Is heat transferred from a cold body to a hotter one?

8. What does the expression “the same temperature” mean?

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

amount, point, indicate, depend, iron, mean.

Exercise 4. Form new words using prefixes and suffixes.

measure, internal, change, consider, boil, similar, quantity, heat, sufficient, transfer, important.

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

1. If the water is heated in a closed container, the temperature and the pressure both rise.

2. Both Lomonosov and his friend Rihman worked at atmospheric electricity. Both of them made experiments on that subject.

3. Take both a small cup of boiling water and a large container also full of boiling water; you will find that both of them have the same temperature.

4. “Work” is both a word used in everyday life and a scientific term.

5. Gases have neither size nor shape.

6. Neither of the two experiments was carried on successfully.

7. Heat was considered to be a weightless substance which was neither created nor destroyed.

8. Neither of the observed substances could be heated to a high temperature.

Exercise 6. Write out the keywords and phrases and make up a plan of the text.

Exercise 7. Make a short summary of the text (5-7 sentences).