Everything Science Grade 10

CHAPTER 1. SKILLS FOR SCIENCE 1.3

SI Units ESAF

We will be using the SI units in this course. SI units are the internationally agreed upon
units.

DEFINITION: SI Units

The nameSI unitscomes from the FrenchSystème International d’Unités,

which meansinternational system of units.

There are seven base SI units. These are listed in table 1.1. All physical quantities have
units which can be built from these seven base units. So, it is possible to create a different
set of units by defining a different set of base units.
These seven units are called base units because none of them can be expressed as combi-
nations of the other six. These base units are like the 26 letters of the alphabet for English.
Many different words can be formed by using these letters.

Base quantity Name Symbol

length metre m

mass kilogram kg

time second s

electric current ampere A

temperature kelvin K

amount of substance mole mol

luminous intensity candela cd

Table 1.1: SI Base Units

The Other Systems of Units ESAG

The SI Units are not the only units available, but they are most widely used. In Science
there are three other sets of units that can also be used. These are mentioned here for

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