ST 3. Dimensions of a solid body

ST 4. Do you know that…?

I. Робота в парах. Прочитайте та перекладіть подані інтернаціональні слова.

сapital

сode

сombination

сommerce

сoncept

distance

engineer

familiar

foot

fundamental

gramme

international

kilogramme

kilometre

list

manipulate

metre

metric

mile

minute

physics

standard

symbol

system

universally

yard

II. Запам’ятайте подані символи та слова.

III. Запам’ятайте подані абревіатури

IV. Прочитайте та перекладіть базовий текст №1(БТ 1).

PHYSICAL QUANTITIES AND UNITS OF MEASUREMENTS

1. Physics is a science based upon exact measurement, so you must be familiar with commonly used measuring devices and the units of measurements.

2. There are three basic concepts: length, mass and time.

3. The units used to measure them are called fundamental units.

4. All other units are called derived units because they can always be written as some combination of the three fundamental units.

5. Let’s take a few examples

Area = length x length x length;

Volume = length x length x length;

Speed = ;

Density =.

6. There are two widely used sets of fundamental units: the Metric System and the English System.

7. The Metric System or the International decimal system of weights and measures is based on the metre and kilogramme.

8. Using metric units distance (length) is usually measured in millimetres, centimetres, metres or kilometres; time is measured in seconds, minutes, or hours; and mass is measured in grammes or kilogrammes.

8. The English system uses the foot, yard and mile as units of length; the ounce, pound and ton as units of force and the second as the unit of time.

9. The chief advantage of the Metric System over the English units is that all metric units are divided into 10 or 100 parts.

10. This enables fractional distances and masses to be expressed as decimals.

11. Decimals, it is well known, are easier to manipulate in the addition, subtraction, multiplication and division of two or more quantities.

12. The Foot-Pound-Second (F.P.S.) System is used in Great Britain and the United States of America. The Metric System (metre-kilogramme-second) is invented in France and accepted universally in science but not in engineering or commerce.

13. Engineers and scientists have produced a code of standard symbols for convenient representation of physical quantities.

V. Знайдіть в базовому тексті відповіді на наступні запитання.

1. What units are used to measure length?

2. What units are used to measure mass?

3. What units are used to measure time?

4. What is the difference between the Metric System and the English System?

5. What is the advantage of the Metric System?

6. How can we represent physical quantities?

7. How do we represent units of measurement?

VI. Анотуйте базовий текст(BT1) українською та англійською мовами.

VII. Прочитайте та перекладіть додатковий текст №1(SТ 1).

MEASURING TEMPERATURE.

There are in general use today four different temperature scales. These are the Fahrenheit, Rankine, Centigrade and Kelvin or absolute. On the Fahrenheit scale the boiling point of water is fixed at 212º, its freezing point at 32º. The equivalent points on the Centigrade (sometimes called Celsius) scale are 100º and 0º, on the Rankine scale they are 672º and 492º and on the absolute scale temperature is measured in degrees Centigrade from the points at which molecular motion ceases. Absolute zero is -273.1 º C.

The thermometers are all identically made but each has a different scale. In the United States, the Fahrenheit scale is commonly used in civil life, and the Rankine scale is used by engineers. Centigrade and Kelvin scales are used in all countries for scientific measurements.

It is frequently necessary to change temperature readings from one temperature scale to another. Fahrenheit reading = Centigrade read + 32 and

Centigrade reading = (Fahrenheit read – 32) .

In short, to convert from the Fahrenheit scale to the Centigrade, subtract 32 and multiply by .

There are formulas for such changes:

º F = 32º + º C

º C = (º F – 32)

32º F = 0º C

64.5º F = 18º C (room temperature)

98.5º F = 37º C (blood heat)

Tº K=tº C+273º

To change the Fahrenheit (or Rankine) scale into the Kelvin scale,

the Fahrenheit scale is changed to a Centigrade scale and then to Kelvin.

The first and still most widely used hotness measuring instrument is the simple “liquid-in-glass” thermometer. The volume of liquid expands when hot so that increasing hotness is indicated by extention of the column of liquid (mercury or alcohol) in the glass stem of the thermometer. The stem has a very narrow uniform bore or capillary which is sealed at the “top” end. The space above the liquid is evacuated. At the “lower” end of the stem the capillary connects to the bulb or reservoir of liquid. The bulb is placed in contact with the sample.

The common thermometer uses a liquid as an agent to measure temperature and retains the liquid in a glass bulb. But if it is necessary to measure very low or very high temperatures, other than mercury thermometers must be employed. At temperatures below -39º C, mercury freezes and becomes a solid; at high temperatures glass melts and becomes a liquid. For both of these temperature extremes, electrical thermometers are commonly used. These instruments operate upon the principle that the resistance a wire offers to a flow of electric current through it changes with temperature. The higher temperature, the greater is the resistance.

An electrical thermometer is based upon a principle, discovered in 1821 by Seebeck, known as the thermoelectric effect. Two pieces of wire, one copper and one iron are joined together at the ends to form a complete loop. When one junction is heated and the other is kept cool, an electric current flows around the loop in the direction indicated by the arrows. The greater the difference in temperature between the two junctions, the greater is the electric current.

VIII. Перекладіть українською мовою наступні вирази:

General use, the boiling point of water, civil life, temperature readings, blood heat, top end, for these temperature extremes, melting point temperature, temperature scale, molecular motion, mercury thermometers, room temperature, heat measuring instruments, a glass bulb, the temperature recording device, in boiling water.

IX. Анотуйте додатковий текст № 1(ST1) українською та англійською мовами.

X. Виконайте наступні завдання:

1. Name the four temperature scales and draw their diagrams.

2. If a Centigrade thermometer indicates a temperature of 16º C, what a Fahrenheit thermometer read in the same room?

3. What temperature on the Centigrade scale and the Rankine scale is equivalent to the following?: 50º F, 77º F, 95º F, 85º F, -40º F?

XI. Прочитайте та перекладіть додатковий текст №2(SТ 2).

MEASUREMENT OF VOLUME

For measuring the volume of a liquid, different graduated glass vessels are available, the choice of which depends on the circumstances. Volumes are measured in cubic centimetres (cu. cm.) or millimetres (ml.). The litre is equal to 1000 cu. cm.

The unit of volume for all scientific purposes is the volume of cube each edge of which is one centimetre in length. This unit is called the cubic centimeter, and is generally written cu. cm. or cm³.

The unit of volume in the metric system is the litre, which is the volume of a kilogramme of pure water at the temperature of its maximum density (4º C). The litre in thus for all practical purposes equal to 1 cubic decimetre.

Different measuring vessels are used in the laboratories. They are: the measuring cylinder, flask, pipette, burette and others. The measuring cylinder is for measuring or pouring out various volumes of liquid; the measuring flask and pipette for obtaining fixed, pre-chosen volumes. The burette delivers any required volume up to its total capacity, usually 550 cu. cm., and is long and thin to increase its sensitivity. The divisions may represent 0.1 cu. cm., while in the case of the measuring cylinder they may represent 1.5 or 10 cu. cm. according to the size of the cylinder.

XII. Анотуйте додатковий текст № 2(ST2) українською та англійською мовами.

XIII. Прочитайте та перекладіть додаткові тексти №3, 4(SТ 3, 4).

DIMENSIONS OF A SOLID BODY

Distances of solid objects for example the diameter of a ball, cannot be measured directly with an ordinary scale. For such measurements as this, callipers are employed. These consist of a pair of hinged curved steel jaws. The jaws are closed until they both touch the object in the position for which a measurement is required and the distance between them is afterwards measured on a suitable place.

DO YOU KNOW THAT…?

The standard unit of mass is the kilogramme, a block of platinum preserved at the International Bureau of Weights and Measures near Paris.

Two copies of this kilogramme are kept in the Vaults of the US Bureau of Standards. The kilogramme is divided into one thousand equal parts called grams.

The standard metre is a platinum-iridium bar which is kept in the Vaults of the International Bureau of Weights and Measures near Paris (France).

When the standard metre was first devised it was intended that it has a length equal to ten-millionth part of the distance from one of the earth’s poles to the equator.

The standard metre is usually divided into 100 equal parts. Each of these parts is called centimetre.

The centimetre is divided into ten equal parts. Each of these parts is called a millimetre.

1 centimetre = 10 millimetres

The millimetre is divided into 1000 equal parts. Each of these parts is called a micron.

1 millimetre = 1000 microns

XIV. Запам’ятайте наступні міри довжини, маси, об’єму, площі, часу, кутів.

Співвідношення між одиницями вимірювання роботи і потужності

1 кВт (kW) = 1.36 кінс. сил. (h. p.)

1 кінс. сил. (h. p.) = 0.736 кВт (kW)

1 кВт · год. (kWhr) = 860 ккал. (kcal)

1 ккал. (kcal) = 0.001163 кВт · год. (kWhr)

XV. Робота в парах. Дайте відповіді на наступні запитання, використовуючи базовий та додаткові текст(ST2).

1. What do we need to make any measurement?

2. What are the quantities of fundamental significance?

3. Why must we consider the units of these quantities first?

4. What main systems of measurement do you know?

5. What is M.K.S. system?

6. In what is its advantage?

7. Describe the main units of this system.

8. What main units does the English System use?

9. What is the difference between the Metric System and English System?

10. Compare the main units of measurement of these systems.

11. Try to convert units of one system to units of the other system.