Dyne
The dyne (symbol dyn, from Greek δύναμις, dynamis, meaning power, force) is a unit of force specified in the centimetre–gram–second system of units (CGS), a predecessor of the modern SI. One dyne is equal to 10−5 N or to 10 nsn (nanosthenes) in the old metre–tonne–second system of units. Equivalently, the dyne is defined as "the force required to accelerate a mass of one gram at a rate of one centimetre per second squared":
- 1 dyn = 1 g⋅cm/s2 = 10−5 kg⋅m/s2 = 10−5 N
- 1 N = 1 kg⋅m/s2 = 105 g⋅cm/s2 = 105 dyn
The dyne per centimetre is the unit traditionally used to measure surface tension. For example, the surface tension of distilled water is 72 dyn/cm at 25 °C (77 °F);[1] in SI units this is 72×10−3 N/m or 72 mN/m.
| newton | dyne | kilogram-force, kilopond |
pound-force | poundal | |
|---|---|---|---|---|---|
| 1 N | ≡ 1 kg⋅m/s2 | = 105 dyn | ≈ 0.10197 kp | ≈ 0.22481 lbf | ≈ 7.2330 pdl |
| 1 dyn | = 10–5 N | ≡ 1 g⋅cm/s2 | ≈ 1.0197×10−6 kp | ≈ 2.2481×10−6 lbf | ≈ 7.2330×10−5 pdl |
| 1 kp | = 9.80665 N | = 980665 dyn | ≡ gn × 1 kg | ≈ 2.2046 lbf | ≈ 70.932 pdl |
| 1 lbf | ≈ 4.448222 N | ≈ 444822 dyn | ≈ 0.45359 kp | ≡ gn × 1 lb | ≈ 32.174 pdl |
| 1 pdl | ≈ 0.138255 N | ≈ 13825 dyn | ≈ 0.014098 kp | ≈ 0.031081 lbf | ≡ 1 lb⋅ft/s2 |
| The value of gn as used in the official definition of the kilogram-force (9.80665 m/s2) is used here for all gravitational units. | |||||
History
The names dyne and erg were first proposed as units of force and energy in 1861 by Joseph David Everett.[2] The natural units listed in the same text (see Farad in this reference), are those of the metre-gram-second amu.[clarification needed]
The names were reused in 1873 by a Committee of the British Association[3] (of which Everett was reporter) that proposed using the centimetre-gram-second system for electrical and dynamical systems.
References
- ^ [1][dead link]
- ^ Rossiter, William (1879). Dictionary of Scientific Terms. London and Glasgow: William Collins, Sons, and Coy. p. 109.
- ^ Thomson, Sir W; Professor GC, Foster; Maxwell, Professor JC; Stoney, Mr GJ; Professor Flemming, Jenkin; Siemens, Dr; Bramwell, Mr FJ (September 1873). Everett, Professor (ed.). First Report of the Committee for the Selection and Nomenclature of Dynamical and Electrical Units. Forty-third Meeting of the British Association for the Advancement of Science. Bradford: Johna Murray. p. 223. Retrieved 8 April 2012.
