Lesson nine Text: What is heat?

I. Read and translate:

What makes one thing hot and another cold? What do the terms ‘hot’ and ‘cold’ really mean? Scientist have worked for a long time to find answer to this question.

Lomonosov was the first to state that heat phenomena were due to molecular motion.

At present, we know that heat is a form of energy. Besides, we know the fact that all substances are made up of little particles called molecules. For example, what process takes place when we place a kettle full of cold water on the fire, in other words, when we want to heat water? The molecules begin to move much faster then, so that every time there is a collision, they jump away from each other much farther than they did before. As a result, the drop of water becomes larger, this means, it expands. In scientific language this property is called expansion.

The much faster molecular movement makes the water first warm, then hot. On taking our kettle from the fire, we expect the molecules to slow down, and indeed the water begins to get colder. When our tea is said to be hot it really means that its molecules are travelling very fast. On the contrary, when the tea is cold, they are moving more slowly.

II. Find:

ANTONYMS		SYNONYMS
at rest solid fast useful charge hot dark negative the first increase wrong valuable	positive right the last decrease liquid in motion invaluable slow useless discharge cold light	to employ to make to travel different like fast to receive liquid	to move quick similar various fluid to do to get to use

III. Form verbs:

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

IV. Translate:

1. Известно, что молекулы движутся в различных направлениях. 2. Говорят, что молекулы воды движутся быстрее, когда её нагревают. 3. Считают, что молекулы холодного вещества движутся медленно. 4. Известно, что при нагревании тела расширяются. 5. Нам известно, что тепло может изменять состояние вещества без изменения температуры.

V. Translate and answer:

1. Что такое тепло? 2. Из чего состоит вещество? 3. Как называются мельчайшие частицы вещества? 4. Что происходит, когда тело нагревается? 5. Существует ли разница температур между холодным и горячим телом? 6. Какой прибор используется для измерения температуры?

VI. Read and translate the following story:

Heat and cold

At a physics lesson the teacher asks 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”, says 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.