# Units of measure

Matter, being a body or a substance, and energy can be quantitatively evaluated. Each characteristic that can be quantified constitutes a physical quantity.

## Physical quantity

Length, mass, temperature, time, volume, strength, amount of matter, etc. These quantities are evaluated by the units of measure adopted by convention and each unit has its symbol.

For example, the m The symbol of the meter. The value of a quantity may be expressed by a number and a unit of measure. Example: 25 ° C, 100m.

## Unit of measure systems

A unit group is known as a unit of measure system. The most used is the SI (International System of Units). Note the SI units:

 GREATNESS UNIT NAME SYMBOL pasta kilogram Kg length subway m time second s electric current ampere THE temperaturethermodynamics Kelvin K area square meter m² pressure Pascal Pan force newton N light intensity Candela CD amount of matter Mol mol velocity meters per second m / s energy joule J Electric tension volt V volume cubic meter m³ potency watt W