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Dyne
The dyne (symbol "dyn", from Greek δύναμις (dynamis) meaning power, force) is a unit of force specified in the centimetre-gram-second (CGS) system of units, a predecessor of the modern SI. One dyne is equal to 10 µN (micronewtons), 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/s^{2} = 10^{−5} kg·m/s^{2} = 10^{−5} N
- 1 Newton = 1 kg•m/s^{2} = 10^{5} g•cm/s^{2} = 10^{5} 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 (SI unit) |
dyne | kilogram-force, kilopond |
pound-force | poundal | |
---|---|---|---|---|---|
1 N | ≡ 1 kg⋅m/s^{2} | = 10^{5} dyn | ≈ 0.10197 kp | ≈ 0.22481 lb_{F} | ≈ 7.2330 pdl |
1 dyn | = 10^{−5} N | ≡ 1 g⋅cm/s^{2} | ≈ 1.0197 × 10^{−6} kp | ≈ 2.2481 × 10^{−6} lb_{F} | ≈ 7.2330 × 10^{−5} pdl |
1 kp | = 9.80665 N | = 980665 dyn | ≡ g_{n}⋅(1 kg) | ≈ 2.2046 lb_{F} | ≈ 70.932 pdl |
1 lb_{F} | ≈ 4.448222 N | ≈ 444822 dyn | ≈ 0.45359 kp | ≡ g_{n}⋅(1 lb) | ≈ 32.174 pdl |
1 pdl | ≈ 0.138255 N | ≈ 13825 dyn | ≈ 0.014098 kp | ≈ 0.031081 lb_{F} | ≡ 1 lb⋅ft/s^{2} |
The value of g_{n} as used in the official definition of the kilogram-force 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.
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