Практическое занятие 5
СВЯЗЬ И СИСТЕМА GPS
COMMUNICATIONS AND GPS
Теоретическая часть
Данный лексический материал предназначен для знакомства и овладения общенаучными терминами, активному использованию предлагаемых слов и словосочетаний, подготовки к чтению, переводу и обсуждению общенаучных текстов.
circumference окружность
consequence последствие
delay задержка
to encounter сталкиваться
instantaneous мгновенный
орtical fiber оптоволокно
relevance уместность
wireless беспроводной
Задания
Задание 1. Прочитайте и переведите текст.
The speed of light is of relevance to communications. For example, given the equatorial circumference of the Earth is about 40,075 km and c about 300,000 km/s, the theoretical shortest time for a piece of information to travel half the globe along the surface is 0.0668 s.
When light is travelling around the globe in an optical fiber, the actual transit time is longer. Furthermore, straight lines rarely occur in global communications situations, and delays are created when the signal passes through an electronic switch or signal regenerator. A typical time as of 2004 for a U.S. to Australia or Japan computer-to-computer ping is 0.18 s. The speed of light additionally affects wireless communication design.
Another consequence of the finite speed of light is that communications between the Earth and spacecraft are not instantaneous. There is a brief delay from the source to the receiver, which becomes more noticeable as distances increase. The communications delay between Earth and Mars is almost ten minutes. As a consequence of this, if a robot on the surface of Mars were to encounter a problem, its human controllers would not be aware of it until ten minutes later; it would then take at least a further ten minutes for instructions to travel from Earth to Mars.
This effect forms the basis of the Global Positioning System (GPS) and similar navigation systems. A position on Earth can be determined by means of the delays in radio signals received from a number of satellites, each carrying a very accurate atomic clock, and very carefully synchronized. To work properly, this method requires that (among many other effects) the relative motion of satellite and receiver be taken into effect, which was how (on an interplanetary scale) the finite speed of light was originally discovered.
Задание 2. Ответьте на вопросы:
1. What is of relevance to communication?
2. Do straight lines occur in global communications situations?
3. Are communications between the Earth and spacecraft instantaneous?
4. How can a position on Earth be determined?
5. Are radio signals received from satellites or Martians?
Вопросы к практическому занятию
1. Можете ли вы сказать, о чем текст, основываясь на заголовке? Выскажите предположения.
2. Какие слова и словосочетания относятся к общенаучному стилю?
3. Озаглавьте каждый абзац текста так, чтобы заголовок выражал основную идею абзаца.
4. Изложите основное содержание текста.
Практическое занятие 6
ГРАВИТАЦИЯ
GRAVITATION
Теоретическая часть
Данный лексический материал предназначен для знакомства и овладения общенаучными терминами, активному использованию предлагаемых слов и словосочетаний, подготовки к чтению, переводу и обсуждению общенаучных текстов.
approximation приближенное значение
to coalesce срастаться, объединяться
to compel заставлять
curvature кривизна, изгиб
distinction отличие
to exert оказывать влияние/давление
fluid жидкость
to govern управлять
motion движение
theory of relativity теория относительности
tide прилив/отлив
vicinity округа, близость
Задания
Задание 1. Прочитайте и переведите текст.
Gravitation
Gravitation is a naturall phenomenon by which objects with mass attract one another. In everyday life, gravitation is most commonly thought of as the agency which lends weight to objects with mass. Gravitation compels dispersed matter to coalesce, thus it accounts for the very existence of the Earth, the Sun, and most of the macroscopic objects in the universe. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth, for the formation of tides; for convection (by which hot fluids rise); for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe.
Modern physics describes gravitation using the general theory of relativity, in which gravitation is a consequence of the curvature of space time which governs the motion of inertial objects. The simpler Newton’s law of universal gravitation provides an excellent approximation for most calculations.
The terms gravitation and gravity are mostly interchangeable in everyday use, but a distinction may be made in scientific usage. “Gravitation” is a general term describing the phenomenon by which bodies with mass are attracted to one another, while “gravity” refers specifically to the gravitational force exerted by the Earth on objects in its vicinity.
Задание 2. Ответьте на вопросы:
1. Is gravitation a natural phenomenon?
2. What is it responsible for?
3. How does modern physics describe gravitation?
4. Are the terms gravitation and gravity interchangeable in everyday use?
5. What provides an excellent approximation for most calculations?
Вопросы к практическому занятию
1. Можете ли вы сказать, о чем текст, основываясь на заголовке? Выскажите предположения.
2. К какому стилю литературы относится предлагаемый текст? Обоснуйте свой выбор.
3. Изложите основное содержание текста.
Практическое занятие 7
НЕЙТРОННАЯ РАДИАЦИЯ И РАСЩЕПЛЕНИЕ ЯДРА