# Text 4. Systems of measurement

Metrology is the study of measurement. In general, a metric is a scale of measurement defined in terms of a standard: i.e. in terms of well-defined unit. Measurement is fundamental to most fields of science, including physics, chemistry and biology. Measurement is the estimation or determination of extent, dimension or capacity, usually in relation to some standard or unit of measurement. The process of measuring involves estimating the ratio of the magnitude of a quantity to the magnitude of a unit of the same type (e.g. length, time, mass, etc.). A measurement is the result of such a process, expressed as the product of a real number and a unit, where the real number is the estimated ratio. An example is 9 metres, which is an estimate of an object’s length relative to a unit of length, the meter. Unlike a count, or integer quantity of items that is known exactly, every measurement is an estimate that has some uncertainty. A count is a natural number and may be exact.

A system of measurement is a set of units which can be used to specify anything which can be measured. Some quantities are designated as fundamental units meaning all other needed units can be derived from them. In most systems, length (distance), weight and time are fundamental quantities; or as has been now accepted as better in science and engineering, the substitution of mass for weight, as a better more basic parameter.

Later science developments showed that either electric charge or electric current must be added to complete the minimum set of fundamental quantities by which all other metrological units may be defined. Other quantities such as power, speed are derived from the fundamental set; for example, speed is distance divided by time.

In antiquity, systems of measurement were defined locally, the different units were defined independently according to the length of a king’s thumb or the size of his foot, the length of stride, the length of arm and so on.

In the metric system and other recent systems, a single basic unit is used for each fundamental quantity. Often secondary units (multiples and submultiples) are used which convert to the basic units by multiplying by ten, i.e., by simply moving the decimal point. Thus, the basic metric unit of length is the metre or meter; a distance of 1.234m is 1234.0 millimetres, or 0.001234 kilometres.

The International System of Units (abbreviated SI) is the modern, revised form of the metric system. It is the world’s most widely used system of units, both in everyday commerce and in science. The SI was developed in 1960 from the metre-kilogram-second (MKS) system. There are two types of SI units, Base and Derived Units. Base units are the simple measurements for time, length, mass, temperature, amount of substance, electric current, and light intensity.

Derived units are made up of base units, for example density is kg/m3.

Before SI units were widely adopted around the world, the British systems of English units and later Imperial units were used in Britain, the Commonwealth and the United States. The Imperial units for distance, weigh and time are foot, pound and second. It is interesting to note that many Imperial units remain in use in Britain despite the fact that it has mostly switched to the SI system. Road signs are still in miles, yards, miles per hour, etc.

Examples of measuring instruments include the thermometer, speedometer, weighing scale and voltmeter. In order to measure accurately, measuring instruments must be carefully constructed and calibrated.

Exercise 39. Translate the following words and word combinations.

The metric system of measurement, decimal scale, light intensity, multiplication table, to a great extent, well-defined unit, units of measurement, real number, unit of length, fundamental units, basic parameter, science development, electric charge, amount of substance, electric current.

Exercise 40. Match the terms in the right and left columns.

 electrical quantities consume scale multiplication measure capacity metrology unit of weight magnitude quantity electric power substance a) речовина b) електроенергія c) кількість d) величина e) одиниця ваги f) метрологія g) ємкість h) вимірювати i) множення j) шкала, масштаб k) електричні величини l) споживати

Exercise 41. Write all derivatives of the following words and give their translation: revise, multiple, estimate, accept, define.

Example:

to measure – вимірювати (v)

measure – міра (n)

measurement – вимірювання (n)

measurable – те, що можна виміряти (adj)

measurability – вимірюваність (n)

measuring (device) – вимірювальний (пристрій) (а)

Exercise 42. Identify by suffixes: a) nouns; b) verbs; c) adjectives; d) participles among the following words. Translate them.

Substitute – substitution – substituted;

determine – determination – determinative – determined;

designate – designation – designated;

quantify – quantification – quantity;

derive – derivation – derivative.

Exercise 43. Fill in the gaps with the words given in brackets below and translate the sentences.

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