III. Read the text and do the tasks following it

Практическое занятие № 1

Тема: Научные слова.

THE WORDS OF SCIENCE

I. First thoughts. What do we call the “words of science”? Where do the terms come from?

II. Study the words. Make sure you know them. Practice the pronunciation.

To accustom, to restrict, to adopt, current, force, resistance, to expand, to widen, to denote, to define, compound, strength, quantitative, weight, rate, fatigue, to crack.

III. Read the text and do the tasks following it.

There are many words of long standing which the scientist has been accustomed to use with a meaning that might or might not be the same as its customary one.

Sometimes he restricts the meaning of the word. The physicist adopted the word "current" when he described the changed properties of a wire connected to a voltaic battery as an electric current. In 1827, G. S. Ohm discovered the constancy of the relation between electromotive force and current and gave the ratio the name of "resistance."

Sometimes, a scientist will take an ordinary word and expand or widen its meaning, so that a single thing gives its name to a group or category.

"Salt," for example, is a material that is essential for human beings and animals, and has a long association with social history.

Its name appears in the English language in such a word—as "salary" meaning that the money one earns is meant, in the first turn, for buying what is most necessary for human existence.

The chemist, however, uses the word to denote a class of compounds, which he defines as the products of replacing the hydrogen of an acid, wholly or in part, by a metal or a metallic radicle. Common salt is a compound which comes only to a limited extent within the terms of this definition and only to this limited extent do these two salts mean the same thing.

Sometimes, a scientist will seize a word and force it to do work for which it has no qualifications. Such is the case of a family of related words — "force," "work," "power" and "weight."

In mechanics, force does not mean strength. It seems to say no more than that a force is a push or a pull, and since in physics all things must be measured it acquires, from Newton's Law of Motion, a quantitative sense which makes it the product of mass and acceleration. This, of course, is quite different from anything that the word "force" implies in everyday use.

A weight, one is surprised to learn, is not only the familiar block of metal with a ring on top, but a force. This is logical, because things fall under their own weight with an acceleration (due to gravity), so that the weight of a thing has to be the force with which the earth attracts it.

As to "work," the physicist has decided that a force works, or does work, only when it moves something. I may push and pull in vain at some immovable obstacle, and find that, nevertheless, mathematically I have done no work.

After this it is quite easy to accept the idea that power has come to mean the rate at which work is done; or that metals suffer from "fatigue" or that oils can be made "to crack."

Scientific words do not change their basic meanings in the course of centuries, as many ordinary words do. This singleness of meaning, this constancy in form and function, give to scientific words a character which distinguishes them from other words, but relates them to the symbols of mathematics.

IV. Comprehension Check.

1. Find the English equivalents for the following words and phrases: электрический ток, электродвижущая сила, усталость, расщеплять, вес, ускорение, ограничивать значение, сопротивление, класс соединений, определять (обозначать), количественное значение, неподвижное препятствие.

Read the text again to decide if the statements are true or false. Correct the false ones with the facts from the text.

1. Sometimes, a scientist uses an ordinary word to give its name to a group or category.

2. The word “salary” origins from the word “salt”.

3. In mechanics, force is used in the meaning of strength.

4. The weight of a thing is the force with which the earth attracts it.

5. Both scientific and ordinary words do not change their basic meanings in the course of centuries.

Make a plan to the text.

Give a summary of the test using the plan.

V. Discuss the following with your groupmates.

Are scientific terms always easy to understand? Why?

 

Практическое занятие №2

Тема: Свойства материалов.

PROPERTIES OF MATERIALS

I. First thoughts. What sciences study the properties of materials?

II. Study the words. Make sure you know them. Practice the pronunciation.

Ability, absorb, amount, application, brittle, constituent, crack, creep resistance, definition, density, ductility, failure, gradual, rigid, to sink, square root, stiffness, strain, strength, stress, tensile strength, toughness, yield strength, Young modulus.

III. Read the text and do the tasks following it.

Density (specific weight) is the amount of mass in a unit volume. It is measured in kilograms per cubic metre. The density of water is 1000 kg/m³ but most materials have a higher density and sink in water. Aluminium alloys, with typical densities around 2800 kg/m³ are considerably less dense than steels, which have typical densities around 7800 kg/m³. Density is important in any application where the material must not be heavy.

Stiffness (rigidity) is a measure of the resistance to deformation such as stretching or bending. The Young modulus is a measure of the resistance to simple stretching or compression. It is the ratio of the applied force per unit area (stress) to the fractional elastic deformation (strain). Stiffness is important when a rigid structure is to be made.

Strength is the force per unit area (stress) that a material can support without failing. The units are the same as those of stiffness, MN/m², but in this case the deformation is irreversible. The yield strength is the stress at which a material first deforms plastically. For a metal the yield strength may be less than the fracture strength, which is the stress at which it breaks. Many materials have a higher strength in compression than in tension.

Ductility is the ability of a material to deform without breaking. One of the great advantages of metals is their ability to be formed into the shape that is needed, such as car body parts. Materials that are not ductile are brittle. Ductile materials can absorb energy by deformation but brittle materials cannot.

Toughness is the resistance of a material to breaking when there is a crack in it. For a material of given toughness, the stress at which it will fail is inversely proportional to the square root of the size of the largest defect present. Toughness is different from strength: the toughest steels, for example, are different from the ones with highest tensile strength. Brittle materials have low toughness: glass can be broken along a chosen line by first scratching it with a diamond. Composites can be designed to have considerably greater toughness than their constituent materials. The example of a very tough composite is fiberglass that is very flexible and strong.

Creep resistance is the resistance to a gradual permanent change of shape, and it becomes especially important at higher temperatures. A successful research has been made in materials for machine parts that operate at high temperatures and under high tensile forces without gradually extending, for example the parts of plane engines.