Posted: Thu Dec 21, 2006 9:24 pm |
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Use google or learn SI units
EDIT:
50.5 cm = the distance light travels in vacuum in the duration of 15.4849761 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at 0K.
3.8 kg = 3.8 times the mass of the international prototype of the kilogram, which is made from an alloy of platinum and iridium of 39 mm height and diameter and is kept at the Bureau International des Poids et Mesures (International Bureau of Weights and Measures), near Paris.