## BIG IDEAS - Seven fundamental units - the units in the revised SI are based completely on seven [[Physical constant|unchanging quantities]] >[!note] >The fundamental SI Units (base units) are all independent of each other and all scientific measurements are expressed in terms of these units. ## About Base Units There are **seven base** SI units based on physical quantities. All other physical quantities come from these base quantities. The MKS system is **meters - kilograms - seconds** as the base for the physical quantities of length, mass, and time. There are times the cgs system is appropriate: **centimeters - grams - seconds**. ![[Notes Vault/Physics Notes Vault/Measurements/SI Units/SI Base Units.png]] ## Examples ## Sources --- Return [[Home|Home]] | [[SI units]] | [[Physical constant|Physical constants]]