Dyne

From Wikipedia, the free encyclopedia
Jump to: navigation, search

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/s2 = 10−5 kg·m/s2 = 10−5 N
1 Newton = 1 kg•m/s2 = 105 g•cm/s2 = 10 5 dyne

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.

Units of force
newton
(SI unit)
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 is used here for all gravitational units.

History[edit]

The names dyne and erg were first proposed as units of force and energy in 1861 by 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[edit]

  1. ^ [1][dead link]
  2. ^ Rossiter, William (1879). Dictionary of Scientific Terms. London and Glasgow: William Collins, Sons, and Coy. p. 109. 
  3. ^ 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.