The units of measurement should be universally accepted ,this means that the majority of the country should be allowed to select the unit by the different countries. There are many different types of units. The units can be converted into the other units of measurement. 

Example of a unit is, kilometre . This refers to 1000 metres being used as a unit or changing the unit of metres measuring the length into kilometres. 

History 

The units of measurement was one of the earliest forms to denote quantities which were required to get standardized. Initial units of measurement were brought as the uniform system of measurement during the 4thand 3rd BC. Various old books and civilisations have had some reference to earlier units of measurement in Egypt, Indus Valley Civilisation, etc.

Necessity of the units 

The units of measurement of any quantity is necessary and required for the following :-

  • Exact values – Units can be calculated therefore we can say that the exact quantity of contribution which can also be availed with the existence of these units of measurement. 
  • Variety – There are many different types and varieties of units which are followed and used in different parts of the world. Therefore , the units of measurements do provide a person with a variety of units required . 
  • Saves from disasters – A widely used unit system prevents ships, planes and helicopters from misreading the radio signals and important voice messages regarding measurements of dangerous circumstances . Eg:- if a plane is told that another plane is flying towards them and they need to ascend 1km to save the passengers but the plane’s system shows height in feet. Then there will be confusion in such cases. 

Types of units 

There are two types of units:- 

  • Derived units – These are those units which are obtained after multiplication, division and various calculations done to the base units of  the quantity. There are some activities which require the relation of two or more natural units ,these resulting units are known as derived units. Eg:- Measurement of speed, work, acceleration, energy, etc. 
  • Base units –  These are the units used to denote quantities such as length , time. Electric current etc. These units  do not need any other units for the derivation. Units like metre, kilo mere a few more are base units of measurement. 

SI units 

The full form of SI units is the International System of Units. Generally it was created as a modern version of the metric system. Currently, SI units are the largest used units of measurement. The SI unit system has 7 base units which are :- 

  • Seconds – It has a symbol of S and it is mainly used for denoting time. 
  • Metre – It is denoted by m and is used to measure length. 
  • Kilograms – Kilograms is written as kg. It helps in denoting and measuring mass of  a body. 
  • Mole – Mole is written as mol and it is a unit about the amount of substance . 
  • Ampere – it denotes electric current and is denoted as A . 
  • Kelvin  – Generally kelvin is the unit of temperature and is denoted as K . 
  • Candela – It denotes luminous temperature and is written as cd in short. 

Other than the main base units there are 22 official units which are derived units. Example :- kilogram per cubic metre is the SI unit of density. 

Unit Conversion

Due to a huge list of units and divided opinion of the people sometimes may require to change from one unit to the preferred unit. The process of conversion mainly surrounds multiplication or division of the result involving any specified required digits , etc. 

Example:- 200 K of temperature, have to convert it to Celsius. 

Formula :-  Temperature in °c  = Temperature in Kelvin – 273.15

Temperature in °c = 200 K -273. 15 

Temperature in °c  =  -73. 15 °c ( Ans) 

Conclusion

The conversion of units can be complicated at times for people . There are so many units of measurement already and changing them into the unit you require them to be in is necessary. However these units need to be conversed in a mathematical form using division and multiplication with particular numbers.