What is commonly used as a unit to measure people's weight, and what can be expressed in letters?

The unit in the weighing scale is generally kilograms, so people's weight is usually measured in kilograms/kilograms, which can be expressed by letters (kilograms).

1kg will be defined as "the mass unit corresponding to Planck constant 6.62607015×10-34js". Its principle is to convert the mechanical force required to move an object with a mass of 1 kg into an electromagnetic force that can be expressed by Planck constant, and then calculate the mass through the mass-energy conversion formula.

The kilogram is a metric unit of measurement, and one kilogram is equal to one kilogram, which is equivalent to two kilograms in China. ?

Plural form: kilograms.

Extended data:

nature

Kilogram is the unit of mass, and mass is equivalent to how "heavy" a thing is every day. However, quality is actually an attribute with "inertia"; In other words, an object will tend to maintain its current speed without external force. When an object with a mass of one kilogram is subjected to a force of one Newton, it will get an acceleration of one meter per square second (about one tenth of the acceleration of the earth's gravity).

The weight of matter depends entirely on the local gravitational intensity, while the mass is constant (assuming that the mass does not move relative to the observer at relativistic speed). Accordingly, astronauts in microgravity can lift objects in the space capsule effortlessly; Because objects are weightless. However, an object still maintains its mass in microgravity, and astronauts need to exert ten times the force to accelerate an object with ten times the mass at the same acceleration.

Development history

The original definition of kilogram is related to the unit of length;

179 1 year: 4℃ 1 cubic decimeter of pure water. The original device was platinum-iridium alloy, which was preserved in Paris and later called the international kilogram original device.

190 1 the third international metrology conference stipulated that the kilogram is the unit of mass (not weight), which is equal to the international original kilogram. The kilogram is represented by the symbol kg. The kilogram force is a commonly used unit of measurement in engineering technology, which is defined as the gravity of the international kilogram original device at the sea level of latitude 45. The symbol is kgf. The word "force" is often omitted in engineering books, which is easily confused with the unit of quality. So in the last century, China stipulated that the use of gravity is also called weight, and the unit is kilogram force.

In April 2008, researchers at the German National Institute of Metrology in Brunswick said that they would use pure silicon with a diameter of 10 cm (4 inches) to define a more standard measurement method.

Until 20 13, a Pt-Ir cylinder with the closest mass to kilograms was kept in a heavily guarded vault in the suburbs of Paris, France, as an internationally unified weight unit. However, due to consumption and wear, its mass is slowly decreasing, the accuracy of basic units is affected, and the error is getting bigger and bigger.

The new pure silicon fuselage is really special, and the construction cost is 2 million euros (about 3.2 million US dollars). Pure silicon combines the strength of Russian, Australian and German scientific elites. It takes five years to manufacture, and the mass is infinitely close to one kilogram. This is a nearly perfect sphere with high purity. 99.99% of the substance is a silicon isotope called silicon 28. Scientists in Brunswick, Germany, began thousands of experiments on pure silicon to calculate the number of silicon atoms that make it up.

2018 165438+1October16 the 26th international metrology conference adopted the resolution of "revising the international system of units", which formally updated the definition of the international standard quality unit "kilogram". ?

2065438+On May 20th, 2009, the new international system of units came into effect.

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