Definition:CGS
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Definition
CGS is the centimetre-gram-second standard system of units of measurement.
This system is rarely used nowadays, the SI units having largely taken over.
CGS Base Units
| Name | Unit symbol | Dimension | Symbol |
|---|---|---|---|
| centimetre | $\mathrm{cm}$ | Length | $l$ |
| gram | $\mathrm g$ | Mass | $m$ |
| second | $\mathrm s$ | Time | $t$ |
CGS Derived Units
Dyne
The dyne is the CGS unit of force.
It is defined as being:
- The amount of force required to accelerate a mass of one gram at a rate of one centimetre per second squared.
| \(\ds \) | \(\) | \(\ds 1\) | dyne | |||||||||||
| \(\ds \) | \(=\) | \(\ds 10^{-5}\) | newtons |
Erg
The erg is the CGS unit of energy:
It is defined as being:
- the energy transferred to (or work done on) a body when a force of $1$ dyne acts on that body in the direction of the force's motion through a distance of $1$ centimetre.
Thus:
- $1 \, \mathrm {erg} = 1 \, \mathrm {dyn} \, \mathrm {cm}$
| \(\ds \) | \(\) | \(\ds 1\) | erg | |||||||||||
| \(\ds \) | \(=\) | \(\ds 10^{-7}\) | joules |
Also known as
CGS can also be presented as c.g.s.
The CGS system is also known as the Gaussian system, for Carl Friedrich Gauss.
This term is used usually in the context of atomic physics and solid-state physics, where their scale is more convenient than that of SI units.
Also see
Sources
- 1964: Milton Abramowitz and Irene A. Stegun: Handbook of Mathematical Functions ... (previous) ... (next): $2$. Physical Constants and Conversion Factors
- 1964: D.E. Rutherford: Classical Mechanics (3rd ed.) ... (previous) ... (next): Chapter $\text I$: Kinematics: $1$. Space and Time
- 1966: Isaac Asimov: Understanding Physics ... (previous) ... (next): $\text {I}$: Motion, Sound and Heat: Chapter $3$: The Laws of Motion: Mass
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): cgs
- 1990: I.S. Grant and W.R. Phillips: Electromagnetism (2nd ed.) ... (previous) ... (next): Chapter $1$: Force and energy in electrostatics: $1.1$ Electric Charge
- 1990: I.S. Grant and W.R. Phillips: Electromagnetism (2nd ed.) ... (previous) ... (next): Appendix $\text A$: Units
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): c.g.s. units
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): c.g.s. units