Подберите русские эквиваленты к следующим словам и словосочетаниям

A	B
1. general 2. term 3. force 4. body 5. by another part 6. from a distance 7. area 8. straight line 9. magnitude 10. of indefinite length 11. opposite 12. point of application 13. to act 14. in special cases 15. equivalent 16. to represent 17. difference 18. to subtract	a. на расстоянии b. действовать c. точка приложения d. термин e. в особых случаях f. площадь g. противоположный h. тело i. представлять, изображать j. прямая линия k. величина l. другой частью m. вычитать n. неопределенной длины o. разность p. получать q. общий r. равнозначный s. направление t. сила

2. Ответьте на вопросы:

1. What is the word “force”?

2. What is a force always exerted by?

3. How may a force act?

4. What is the line of action of any force?

5. What quantities are forces?

6. Can ordinary arithmetic rules be applied to vector quantities?

7. How can forces be represented?

8. Where does a body move under the action of two forces?

Перескажите текст B.

4. Переведите следующие группы слов с предлогами:

At the theatre; at the lesson; at the blackboard; at the table; at the congress; at the window; from the Institute; in the room; on the table; in the bag; in the park; on the page ten; in foreign languages; after many years; after the lectures; for ten months; to be on each side; a lecture on the Moon; on the 7th of October; on Sunday; a specialist in chemistry; to meet in the evening; to come back in two years; to be in motion.

5. Переведите на английский язык следующие группы слов, используя в качестве определения существительное в притяжательном падеже:

Книга друга, открытие Ньютона, фамилия ученого, стол инженера, недельный отпуск, работа студентов, интересы народа, доказательства Максвелла.

Переведите на английский язык следующие группы слов, используя в качестве определения существительное с предлогом “of”.

Прогресс науки; библиотека института; название статьи; страница книги; план работы; развитие теории; обсуждение проблемы; направление силы; длина линии; величина заряда.

UNIT 4

Text A

Overview of Types of Welding

The different processes for joining metal parts can be systematically subdivided into different categories depending on their action principle. Their bond can be form-closed, frictional or positive-substance bond. Very often, it is not possible to make a clear distinction between closing shape and frictional bond, as some processes render a clear distinction between operating principles impossible.

A positive substance bond is mostly inseparable, and the bond takes place only by using additional material or consumables. The most frequent types of joints in this category are adhesive, soldered, brazed and welded joints. When welding materials, one has to distinguish between fusion welding and pressure welding.

Fusion and Pressure welding

Fusion welding leads to a welding of the pieces by applying heat at the point of connection which fuses the pieces together and even joins a material. After the hardening of the mixed components, a solid joint occurs. Unlike fusion welding, pressure welding depends on the application of high pressures and/or high temperatures, resulting in a strong plastification and a local deformation of the pieces to be joined in the welding area so that a bond between both pieces is made. The energy required for the welding process is of a different kind for both types of procedure.

Proven energy sources here are gas, arc welding, light, electron or plasma beams.

Ultrasonic welding belongs in the category of pressure welding and uses motion and kinetic energy for welding pieces together.

Depending on the kind of motion, a distinction in metal welding between cold-pressed welding, friction welding and ultrasonic welding can be made. All three procedures show a high similarity. Ultrasonic metal welding is a combination of cold-press welding and friction welding because of its mode of action.

Cold-press welding takes place at room temperature. By applying high pressures to both pieces the materials weld together. A strong material deformation at the welding zone accounts for the bond.

The differences between the various metal welding processes

In the friction welder, one or both pieces rotate while they are pressed together. The frictional heat which emanates together with the static pressure causes the bond between the pieces. The back pressure required for joining the pieces in comparison to cold-press-welding is drastically reduced because of the additional rotational energy. The matching of the surfaces promotes plastification and local deformation of the pieces being welded.

A considerably lower welding pressure

During ultrasonic metal welding, the rotational motion is replaced by mechanical linear vibrations. The welding surfaces are periodically scrubbed during the welding process. This further reduces the required welding pressure compared to friction welding, the final value being only about 1% of that required for cold-press welding.