'Secrets' of the standard mass of US stored in a vacuum glass cage

The standard US kilogram block is K20, which is extremely well preserved and is vacuum-glazed.

We all know Americans use different units to calculate mass or distance, unlike most countries in the world that use metric systems. But in fact, Americans have also used the same measurement system of the world for a very long time.

Vlogger Derek Muller of Veritasium went to the US National Institute of Standards and Technology (NIST) to see K20 - one of 40 identical standard kilograms produced by the French in 1880, suggesting that Americans still use Use the kilogram at this time.

The American relationship with the metric system was very strong in the 19th century, when France introduced this metric to Americans and gave them the K20 block after signing the Meter Agreement in 1875. The 17 states agreed. Standard use of this measurement system.

The international standard kilogram block is produced and issued to countries around the world to help countries determine what a standard kilogram is.The standard US kilogram block is K20 , which is extremely well preserved and is vacuum-glazed.

Standard kilogram block K20 at the National Institute of Standards and Technology.(Photo: NIST).

The reason the standard kilogram block has to be extremely well preserved is because if only one molecule is added or lost from the standard kilogram, its mass will go away and the definition of kilogram will be changed.

'The standard kilogram is made up of 90% platinum and 10% iridium, with an exact weight of 1 kg used as the benchmark for mass measurement in the United States for the last 130 years , Derek Muller explained.

The standard kilogram is made up of these two elements, because of its high molecular density and good antioxidant capacity, making the standard kilogram block last long without the difference in measurement. Although machines are very good today, this kilogram is still an invaluable item, irreplaceable.

However, the K20 block did not work well for long. Derek said, the kilogram is a unit of measurement defined by physical entities rather than a mathematical constant or a fixed thing found in nature, which creates some difficulties.

Every decade in the 1800s, American scientists had to fly to Paris to check their K20 block to standardize with international standard kilograms in France, to ensure that the measurements in the two countries were not different. mismatches. Sometimes the results are skewed even though they are very well preserved, scientists predict that due to atmospheric pollution.

To this day, NIST and other agencies and organizations are constantly trying to define the kilogram more physically and accurately. From 2018, the kilogram will be determined by the Planck constant, creating a fixed value from measurements that can be used worldwide.

So, Americans abandoned the metric system later in 1987, because of the inaccuracies of these quantities. Americans measure everything from distance, mass, area or volume by units calculated from fixed constants in mathematics.