View source for Centimeter-gram-second system

The '''centimeter-gram-second system''' (abbreviated cgs) of physical units of measure is a nearly obsolete system that was in widespread use in the nineteenth century, until the [[meter-kilogram-second system]] (mks), with its much larger units, replaced it. The main distinguishing feature of the cgs system is that most of its units are named for the physical properties they are supposed to measure, rather than for famous scientists, as is the case with the mks and [[International System of Units|SI]] systems.

== Definitions ==
=== Time ===
The one unit that cgs shares with SI is the unit of [[time]], the [[International System of Units#Second|second]]. Its definition history is the same as for the SI second.

=== Length ===
The cgs unit of [[length]] is the centimeter, or one-hundredth of a [[meter]].

=== Mass ===
The cgs unit of [[mass]] is the gram. Originally (see [[Metric system]]) this was the primary unit of mass. Today a gram is defined as one-thousandth of a [[kilogram]].

=== Dynamics ===
==== Force ====
The cgs unit of [[force]] is the '''dyne''' (from the [[Greek]] '''δύναμαι''' or ''dunamai'' I can). One dyne is the amount of force needed to accelerate a one-gram mass one centimeter per second per second.
==== Pressure ====
The cgs unit of [[pressure]] is the '''barye'''. One barye exerts one dyne of force on every square centimeter of area.

=== Work and power ===
The cgs unit of work and [[energy]] is the '''erg''' (from the [[Greek]] '''εργον''' or ''ergon'' work). One erg is the amount of work done when exerting a force of one dyne over one centimeter, or the energy required to do that work.

The cgs system does not, properly speaking, have a separate unit of power. Instead, it expresses power in ergs per second.


[[Category:Units of Measurement]]