Mass-Kilogram

Jason Jia: How is the kilogram being defined? The kilogram is defined as being equal to the mass of the //International Prototype Kilogram// (IPK), which is almost exactly equal to the mass of one litre of water. Jason Lim: Kho Wen Hao:

Samuel Kng:

Koh Han Wei: How **__//was//__** the kilogram being defined and how did it evolve? The gram was decreed to be equal to the mass of water in a centimeter cube, at waters melting point, 0°C, in France, on the 7th April 1795. They took the concept from the English Philosopher, John Wilkins, in 1668, when he thought of using a unit to define a mass. However, since trade usually handled objects a few hundreds of folds larger than a gram, they decided to make the kilogram, a more standard measurement used. It was soon realized that the definition of the original gram using 0 °C was highly unstable. Hence, two scientists, French chemist Louis Lefèvre-Gineau and Italian naturalist Giovanni Fabbroni, spent several years researching to increase the accuracy of the definition. 4 years after the first definition was placed, a new definition took over. They changed the temperature relative to the density from 0°C to 4°C, where water was supposedly the densest. They still realised that the old kilogram definition was a tad inaccurate, where a thousand cubic centimeters of water at its maximum density was 99.93% the target mass of the standard kilogram. The same year, a kilogram of pure platinum prototype was made the closely resemble the best definition. The standard of these two brilliant scientists stood for another ninety years.

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