Heat transfer

TEXTS FOR LISTENING

ANNOTATION

ANY

SOME

1) деякі, декілька; в стверджувальних реченнях:

We’ll discuss some problems at the conference.

2) перед незлічуваними іменниками, замінюючи артикль; на українську мову не перекладається:

Let’s have some tea.

3) приблизно; вживається перед числівником:

There are some 20 people in the room.

1) будь-який; перед злічуваним іменником в однині в стверджувальному реченні:

You can buy this book at any book-stand.

2) який-небудь; перед іменником у запитальному реченні:

Is there any news from him?

3) ніякий; в заперечних реченнях:

He has not asked any questions.

1. The title (headline) of the article (text) is....

2. The author of the article (text) is... (unknown); group of authors.

3. The article (text):

- to be devoted to; - to be interesting; - to be worth reading.

- to be useful; - to be scientific;

4. The article/the author:

- to speak about; - to mention; - to discuss;

- to describe; - to underline; - to report;

- to pay attention to; - to consider; - to touch upon;

- to prove; - to do research in; - to study;

- to point out; - to single out; - to analyze;

- to characterize; - to substantiate; - to generalize;

- to give reasons for; - to argue; - to classify (group)

- to give photos, figures, facts, tables, equations, formulas, graphs, proofs; details, definitions, arguments, results.

5. The main idea is....

6. I recommend everybody to read it.

Heat can travel throughout a burning building by one or more of four methods: conduction, radiation, convection, direct flame contact. The existence of heat within a substance is caused by molecular action. Thus, as the vibration of the molecules becomes more intense, the heat becomes more intense. Since heat is disordered energy, it never remains constant but is continually transferred from objects of higher temperature to those of lower temperature. The colder of two bodies in contact will absorb heat until both objects are the same temperature.

Heat may be conducted from one body to another by direct contact of the two bodies or by heat-conducting medium. The amount of heat that will be transferred and its rate of travel by this method depend upon conductivity of the material through which the heat is passing. Not all materials have the same heat conductivity. Aluminum, copper, and iron are good conductors. Other solids such as stone and wood are poor conductors. Fibrous materials, such as felt, cloth, and paper are poor conductors. Liquids and gases are poor conductors of heat because of the free movement of their molecules. Air is a very poor conductor. Double building walls which contain an air space provide additional insulation.

The next method of heat transmission is known as radiation of heat waves. Heat and light waves are similar in nature but they differ in length. Heat waves are longer than light waves and they are sometimes called infrared rays. Radiated heat will travel through space until it reaches an opaque object. As the object is exposed to heat radiation it will in return radiate heat from its surface. Radiated heat is one of the major sources of fire spread.

Дата добавления: 2014-12-29