Reference Data for Engineers, 9th Edition

3 Units, Constants, and Conversion Factors

Revised byEugene A. Mechtly

SI Units

SI Base Units

SI Derived Units

SI Prefixes

Additional Information on the SI

Units outside the SI

Rules and Style Conventions

Dimensionless Quantities (Quantities of Dimension 1)

Decibels and Nepers

Numerical Values

Greek Alphabet

Fundamental Physical Constants

Conversion Factors

SI UNITS^*

There are two classes of units in the International System of Units (SI): base units and derived units. The units of these two classes form a coherent set of units. This coherent set of units is designated by the name “SI Units.”

SI Base Units

The SI is founded on seven base units, respectively, for seven base quantities. The base quantities are assumed to be mutually ...