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
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