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The kilogram doesn't weigh a kilogram any more. This sad news was announced during a seminar at CERN on Thursday, 26 October by Professor Klaus von Klitzing, who was awarded the 1985 Nobel Prize in Physics for the discovery of the quantised Hall effect. "We are about to witness a revolutionary change in the way the kilogram is defined," he declared.
Together with six other units – metre, second, ampere, kelvin, mole, and candela – the kilogram, a unit of mass, is part of the International System of Units (SI) that is used as a basis to express every measurable object or phenomenon in nature in numbers. This unit's current definition is based on a small platinum and iridium cylinder, known as "le grand K", whose mass is exactly one kilogram. The cylinder was crafted in 1889 and, since then, has been kept safe under three glass bell jars in a high-security vault on the outskirts of Paris. There is one problem: the current standard kilogram is losing weight. About 50 micrograms, at the latest check. Enough to be different from its once-identical copies stored in laboratories around the world.
To solve this weight(y) problem, scientists have been looking for a new definition of the kilogram.
Dang. That throws the easily memorable conversion of 1kg=2.2lbs right out the window.
(Score: 5, Informative) by Runaway1956 on Tuesday November 07 2017, @03:47AM (1 child)
Forget about Jupiter. A give mass will weigh dirrently, depending on where you weigh it, right here on earth.
https://en.wikipedia.org/wiki/Gravity_of_Earth#Variation_in_gravity_and_apparent_gravity [wikipedia.org]
Also, from the same page,
https://en.wikipedia.org/wiki/Gravity_of_Earth#Comparative_gravities_in_various_cities_around_the_world [wikipedia.org]
Comparative gravities in various cities around the world
Tools exist for calculating the strength of gravity at various cities around the world.[13] The effect of latitude can be clearly seen with gravity in high-latitude cities: Anchorage (9.826 m/s2), Helsinki (9.825 m/s2), being about 0.5% greater than that in cities near the equator: Kuala Lumpur (9.776 m/s2), Manila (9.780 m/s2). The effect of altitude can be seen in Mexico City (9.776 m/s2; altitude 2,240 metres (7,350 ft)), and by comparing Denver (9.798 m/s2; 1,616 metres (5,302 ft)) with Washington, D.C. (9.801 m/s2; 30 metres (98 ft)), both of which are near 39° N. Measured values can be obtained from Physical and Mathematical Tables by T.M. Yarwood and F. Castle, Macmillan, revised edition 1970.[14]
As you can see, you can move a "perfectly" defined and calculated kilogram from one spot on the earth to another, and find that your kilogram isn't so perfect after all.
BUT - as has already been pointed out, a kilogram isn't a unit of weight at all, but a unit of mass. Despite different weights in different places, that "perfect" example of a kilogram is still a kilogram. Outside influences simply act on that kilogram differently.
(Score: 2) by bob_super on Tuesday November 07 2017, @05:46PM
> and find that your kilogram isn't so perfect after all.
> Despite different weights in different places, that "perfect" example of a kilogram is still a kilogram. Outside influences simply act on that kilogram differently.
A lot of words to repeat what women all know: Men can't seem to measure properly.