why is SI importent?

Answer 1

you mean by metric units? it's used internationally

Answer 2

It is the system internationale or international system for naming and using units of measurement. It is important so that people from around the world measure things using the same units and they can thus compare those measurements much easier than if they used different units

Answer 3

The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent, as given in Table 1.


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Table 1. SI base units
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SI base unit
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Base quantity Name Symbol
length meter m
mass kilogram kg
time second s
electric current ampere A
thermodynamic temperature kelvin K
amount of substance mole mol
luminous intensity candela cd


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For detailed information on the SI base units, see Definitions of the SI base units and their Historical context.

SI derived units

Other quantities, called derived quantities, are defined in terms of the seven base quantities via a system of quantity equations. The SI derived units for these derived quantities are obtained from these equations and the seven SI base units. Examples of such SI derived units are given in Table 2, where it should be noted that the symbol 1 for quantities of dimension 1 such as mass fraction is generally omitted.