Текст по теме "Метрическая система" и задания к нему

The metгic system

Physics measures such physical quantities as time, length, mass, density, velocity, area, volume, temperature and energy. Different units of length and mass exist. Nearly all of them are interrelated. Nowadays, three main systems of measurement are widely used: the British system of unity, the metric system of units and the Interactional system of units (SI).

With а few exceptions, all the nations of the world use the metric system. It is so easy that anyone who knows arithmetic can learn it quickly. Before the introduction of the metric system (metre-kilogram-second), the British foot- pound-second system was widely used. But the latter system (which is still in use in Great Britain and the USA) was very complicated and caused serious difficulties in the intemationa1 trade. For example, in the British system 1 mile is equal to 1760 yards, 1 yard - to feet and 1 foot- to 12 inches. This means that it's very difficult to convert units. But in the metric system each unit is а multiple of the following lower unit bу ten. Therefore, the conversion to а higher quantity is done bу moving the decimal point to the right to the required number of p1aces, and vice versa.

The idea of decimal system was realised only at the end of the 18^th century. In 1791, the French Academy of Science decided that the standard of length should bе one ten-millionth part of the distance from the Equator to the North Pole. The two French scientists charged with the task took this distance on а line running through Paris and divided it into 10 000 000 equal parts. They called one of the parts а metre ('measure'), which became the main unit. Metre was also used to measure area and volume. Thus а square metre and а cubic metre appeared.

The main advantage of the system is that for shorter measurements the metre is divided bу ten, so а decima1 system was used. Shorter units had Latin prefixes and longer ones - Greek prefixes. So, 'millimetre' is Latin for 'а thousandth part of а metre' and 'kilometre' is Greek for 'а thousand metres'.

As for the unit of mass, it was defined as the mass of а cubic centimetre of water at the temperature of 4°с (the temperature of its maximum density). As we know, the name of this unit is gramme.

The SI units is derived from the metric system and was internationally accepted in 1960. Besides metre (m), kilogram (kg) and second (s), its basic units are Kelwin (К), ampere (а), mole (mol), and candle (cd). This system was introduced in our country in the 1960s and every day we measure things bу the units from this system.

Active Vocabulary

advantage преимущества

area площадь

arithmetic арифметика

basic базовый

British Британский

candle 1. свеча 2. кандела

(единица измерения света)

cause служить причиной

centimetre сантиметр

charge поручать

complicated сложный

conversion пересчет,

convert переводить

(единицы)

cubic кубический

decimal десятичный

define определять

density плотность

derive выводить; проиcходить

distance расстояние

equal равный

equator экватор

exception исключение

gram(me) грамм

Greek греческий, греческий язык

inch дюйм

interrelated взаимосвянный

kilometre километр

Latin латинский; латинский язык

length длина

line линия

mass масса

measure мера

measurement измерение

metre метр

metric метрический

mile миля

millimeter миллиметр

mole моль (единица измерения)

multiply умножать

nation нация

nearly почти

North Pole Северный полюс

pound фунт

prefix (лингв.) приставка, префикс

quantity количество

realize реализовать

require требовать

science наука

scientist ученый

second секунда

trade торговля

square квадрат, квадратный

standard стандарт,

introduce зд. вводить

system система

kilogram(me) килограмм

ten-millionth десятимиллионный

therefore поэтому

thousand тысяча

through сквозь

thus таким образом

unit единица

unity единство

vice versa лат. наоборот

volume объем

widely широко

уагd ярд

EXERCISES

1. Answer the following questions to the text.

1. What quantities does physics mcasure? Аге most of them interrelated?

2. How many systems of measurement are widely used nowadays?

3. All the nations of the world use the metric system, don't they?

4. What was used before the metric system? Did the earlier system have any drawbacks?

5. When was the idea of decimal system realised?

6. What is the main unit of the metric system? How was it measured?

7. Were the units of area and volume defined as well?

8. Do shorter units have Greek or Latin prefixes?

9. What is а unit of mass?

10. Is there а difference between the metric system and the Sl system?

11. When was the SI system introduced in the USSR?

12. What synonyms to the phrase 'metric system' can you find in the text?

2. Study the Active Vocabulary. Inseгt the missing woгds.

1. Can you _ cubic metre into cubic centimetres?

2. The between Moscow and Samara is 1049

3. 'Biology' is а _word, and 'science' is а _one.

4. The teacher _ one of his pupils with а difficult task.

5. Newton was а great _ who formulated laws of gravitation.

6. What is the _ of this swimming pool? - The swimming pool is twenty-five _long and two _deep, and ten _wide. So, 1 _ twenty-five bу two and bу ten and 1 get five hundred __ .

7. The _of ice is more than the _of water as а liquid. But the _ of ice is less than the of water at 4 °С.

8. Who was the first traveler who reached the south ?

9. The_that studies stars is astronomy.

10. The _ units of the _ systems are а metre, а_and а_.