A unit of measurement is a standardized quantity of a physical property, used as a factor to express occurring quantities of that property. Units of measurement were among the earliest … See more

For most quantities a unit is necessary to communicate values of that physical quantity. For example, conveying to someone a particular length without using some sort of unit is … See more

One example of the importance of agreed units is the failure of the NASA Mars Climate Orbiter, which was accidentally destroyed on a mission to Mars in September 1999 (instead of entering orbit) due to miscommunications about the value of forces: different … See more

• Rowlett, Russ (2018) How Many? A Dictionary of Units of Measurement
• NIST Handbook 44, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices
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The use of a single unit of measurement for some quantity has obvious drawbacks. For example, it is impractical to use the same unit for the distance between two cities and the length … See more

Units can only be added or subtracted if they are the same type; however units can always be multiplied or divided, as George Gamow used to explain. Let $${\displaystyle Z}$$ be "2 metres" and $${\displaystyle W}$$ "3 seconds", then See more

• Dimensional metrology
• Forensic metrology
• Smart Metrology
• Time metrology
• Quantum metrology See more