Definition of Measurement Units

Unit is a necessary and important quantity in physics. This article covers measuring units, length and weight of given objects, and the amount of a substance. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. A unit of measurement is a standardised quantity of physical property used as a component to express existing quantities of that property. 

Unit of measurement

A unit of measurement is a definite magnitude of a quantity, defined, and adopted by convention or law and used as a standard for measuring the same kind of quantity.

Measurement is a procedure of deducing how large or small a physical quantity is as described by a basic reference quantity of a similar kind. 

Units are precepts for measuring physical quantities that require realistic definitions to be useful. 

Magnitudes of measurements are typically given in terms of a specific unit. The most commonly used units define quantities of length (or distance), area, volume, and horizontal or vertical angles in surveying. 

The two systems used for specifying units of measure are the English and metric systems. Units in the English system are historical units of measurement used in systems. The metric system is a decimalised system of measurement developed in France in the late 18th century. Since the metric system is almost universally used, it is often referred to as the International System of Units and abbreviated SI.

Reproducibility of observed results is prominent in the scientific method. A standard system of units stimulates this. Scientific operations of units advance the theory of weights and measures historically expanded for commercial goals. 

Using a single unit of measurement for some quantity has obvious drawbacks. For example, it is impractical to use the same unit for the distance between two cities and the length of a needle.

Examples of Measurement Units

The following are the basic quantities being measured and the respective units used. 

Standard units are commonly used units of measurement, which help us measure length, height, weight, temperature, mass, and more. These units are standardised, which means that everyone gets the same understanding of the size, weight and other properties of objects and things.

Length of a given object 

We have different units of measurement to measure lengths. The bigger unit of measuring length is a kilometre. Smaller measurement units are decimeters, centimetres and millimetres.

We know that the standard unit of length is ‘metre’, which is written in short as ‘m’. A metre length is divided into 100 equal parts. Each part is named centimetre and written in short as ‘cm’. Mostly we use kilometres (km), metres (m), and centimetres (cm) as the units of length.

Looking at the ruler, you can find that one centimetre is divided into 10 equal parts marked by smaller lines. Each line represents 1 millimetre. So, 10 millimetres is equal to 1 cm. 10 mm = 1 cm.

The higher unit to measure the length is a kilometre. We already know that 1 kilometre = 1000 metres.

Weight of the given object 

Weight is the measure of how heavy an object is. It is measured in standard customary units.

The unit of measurement for weight is that of force, which in the International System of Units (SI) is the Newton. For example, an object with a mass of one kilogram weighs about 9.8 Newtons on the surface of the Earth and about one-sixth as much on the moon. 

We know the main standard unit of mass or weight is kilogram which we write in short as ‘kg’. 1000th part of this kilogram is a gram written in short as ‘g’. The following units express weights: tonne, kilogram, histogram, decagram, gram, decigram, centigram, and milligram. 

Amount of substance 

The amount of substance in a given sample of matter is defined as the quantity or number of discrete atomic-scale particles divided by the Avogadro constant NA. Depending on the context, the particles or entities may be molecules, atoms, ions, electrons, or others and should be specified. 

The mole is defined as the amount of substance in 12 grams of the carbon-12 isotope. As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule of the compound in daltons, and the molar mass of an isotope in grams per mole is equal to the mass number.

The SI unit of concentration of the amount of substance is the mole per cubic metre (mol/m3).

Conclusion

A unit of measurement is used as a standard to express a physical quantity. It can be said that the units of measurement were among the early tools evolved by humans. We can measure various quantities like length, weight, mass, temperature, etc. In this article, we have learned about the length and weight of an object and the amount of a substance. By learning units of measurement, you can measure quantities accurately.