How do companies that make measuring tools like rulers make sure the product is accurate? Is there a universally ruler that is used to check? How do they make sure the measurements are exact?
In: Engineering
Official measurements are defined using actual physical items. Like there’s a one-kilogram metallic weight at some university (likely in the UK) that is the definition of a kilogram. I believe wavelengths of light are used to define distances. But those are really only useful in scientific situations (where they likely use lasers or other means to measure stuff anyway). The rulers and tape measures you use at home or school are just “close enough”. If you grab a tape measure from two different manufacturer, they will likely get out of sync the further along you go. After 25 feet, they might be off by 1/16 of an inch, for instance. Again, it’s close enough for daily use.
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