One avoirdupois pound can be divided into 16 avoirdupois ounces and 7000 grains. The international avoirdupois pound has no descriptive definition. Of course, this unit is used also in another systems. The pound is used in the Imperial and United States customary systems of measurements. In this article we want to focus only on pound-mass. What does it mean? For instance, there are also pound-force. It is needed to emphasize that there are more than one kind of pound. You know a little about kilogram, so now we can move on to the pound. It can be also divided into 100 decagrams and 1000 grams. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10−34 when expressed in the unit J⋅s, which is equal to kg⋅m2⋅s−1, where the metre and the second are defined in terms of c and ΔνCs.” The official definition is: “The kilogram, symbol kg, is the SI unit of mass. The new definition of the kilogram is based on physical constants, especially Planck constant. The IPK was used until 2019, when it was replaced by a new definition. The IPK was made of 90% platinum and 10 % iridium. Then, in 1889 the kilogram was defined by the International Prototype of the Kilogram (in abbreviated form IPK).
This definition was simply but totally impractical to use. The kilogram was defined as the mass of one liter of water. The symbol of this unit is kg.įirst definition of a kilogram was formulated in 1795.
Sometimes the kilogram is written as kilogramme. It is a base unit in a metric system, known also as International System of Units (in abbreviated form SI).
0 kommentar(er)
