1. Complete the sentences from the text:

1. These two equal and opposite forces, …….., are not related to or by Newton's third law.

2. Newton's first law is a restatement of the principle of … .

3. Newton used the word “motion” to mean what is today called …. .

4. To every …. there is always opposed an equal reaction.

2. Answer the questions:

1.What is the second law of Newton?

2. Are two forces an action and reaction pair operating on different bodies as required by Newton's third law?

3. Are these two equal and opposite forces, acting on the same body, related to or by Newton's third law?

4. What is the first law of Newton?

3. Give the English definitions of the following words :

Net, equilibrium, velocity, deformation, gravity, device

Text 4 The ancient Chinese system

Vocabulary

1. fluctuate- колебаться

2. inclusion-включение

3. noteworthy-достойный

4. acoustic-акустика

5. predilection-склонность

6. vessel- сосуд

7. millet- пшено

Completely separated from the Mediterranean-European history of metrology is that of ancient China; yet the Chinese system exhibits all the principal characteristics of the Western. It employed parts of the body as a source of units—for example, the distance from the pulse to the base of the thumb. It was fundamentally chaotic in that there was no relationship between different types of units, such as those of length and those of volume. Finally, it was rich in variations. The mou, a unit of land measure, fluctuated from region to region from 0.08 to 0.13 hectare (0.2 to 0.3 acre). Variations were not limited to the geographic; a unit of length with the same name might be of one length for a carpenter, another for a mason, and still another for a tailor.

Shih huang-ti, who became the first emperor of China in 221 BC, is celebrated for, among other things, his unification of the regulations fixing the basic units. The basic weight, the shih, or tan, was fixed at about 60 kilograms (132 pounds); the two basic measurements, the chih and the chang, were set at about 25 centimetres (9.8 inches) and 3 metres (9.8 feet), respectively. A noteworthy characteristic of the Chinese system, and one that represented a substantial advantage over the Mediterranean systems, was its predilection for a decimal notation, as demonstrated by foot rulers dating back as far as the 6th century BC. Measuring instruments, too, were of a high order.

A unique characteristic of the Chinese system was its inclusion of an acoustic dimension. A standard vessel used for measuring grain and wine was defined not only as to weight but also as to pitch when struck; given a uniform shape and fixed weight, only a vessel of the proper volume would give the proper pitch. Thus the same word in old Chinese means “wine bowl,” “grain measure,” and “bell.” Measures based on the length of a pitch pipe and its subdivision in terms of millet grains supplanted the old measurements based on the human body. The change brought a substantial increase in accuracy.