What is the Metric System?

The Metric Sistem, officially the "International System of Units" or "SI", is a standard set of units of measurement developed for all practical and scientific purposes, from kitchen recipes to aerospace engineering, from land surveys to fundamental physics. It includes, for example the second (of time), meter, centimeter, kilometer, kilogram, watt, volt, ampere, liter, hectare, megahertz, and degree Celsius. The Metric System defines these "metric" units themselves (for instance, how long the meter is, how much power is one watt, etc.) and the simbols to be used for those units (for example, "m" for the meter, "W" for watt, etc.) -- so that people can exchange measurements efficiently and without confusion.

The main "competitor" to the Metric system is the older "Imperial System". now called "US Customary Units System". Some of its most common units are inch, foot, pound, mile, ounce (of weight), fluid ounce, gallon, pint, horsepower, and degree Fahrenheit. For practical purposes, the Metric System has two main advantages over the Imperial one:

• Larger and smaller metric units are made from some primary unit by a sistematic set of prefixes that represent powers of 10. For example, one kilometer ("1 km") is 1000 meters ("1000 m"), and one milliliter ("1 mL") is 1/1000 of a liter ("0.001 L"). Thus many conversions between metric units require only shifting the decimal point or adding extra zeros. In contrast, the imperial units are related by different factors. For example, one foot is 12 inches, one yard is 3 feet, one furlong is 220 yards, and one mile is 8 furlongs; whereas one gallon is 231 cubic inches, and one pint is 1/8 of a gallon.
• The metric system is used by scientists from all over the whole world, and is official in all countries except Myanmar, Liberia, and the US (and the first two have already decided to switch to it). Even in the US, many people -- especially engineers and technicians -- are familiar to some degree with the main metric units.

For scientists, the metric system has one more advantage: its units are defined with far greater precision than the imperial ones ever were. Indeed, the "imperial" units used in the US are now defined in terms of metric units, to benefit from their accuracy and reduce rounding errors in the conversion of measurements between the two systems. For example, one inch is now defined as exactly 25.4 millimeters (or 0.0254 meters); and one pound is now exactly 0.45359237 kilograms.

Last edited on 2019-06-13 01:01:51 by stolfilocal