Presentation on theme: "The SI System. What is the SI System? The SI System (or the International System of Units) is the modern form of the metric system derived from 7 base."— Presentation transcript:
What is the SI System? The SI System (or the International System of Units) is the modern form of the metric system derived from 7 base units and the convenience of using multiples and fractions of the number 10. The SI System is the world’s most widely used system of measurement with the USA being the only industrialized nation that does not use it as its primary system of units for commercial activity (although, the SI System is widely used in scientific fields in the USA).
The 7 Base units of SI System Unit NameUnit SymbolQuantity measured metermlength kilogramkgmass secondstime ampereAelectric current kelvinKtemperature molemolamount of a substance candelacdluminous intensity
How to use the SI System’s “Base 10” system. Factors > 1 For Example: A car weighs 3000 grams. In this case, a better way to represent the car’s mass would be to use the SI unit kilogram that best corresponds with the value. Therefore, the car weighs 3 kilograms, which is equivalent to 3000 grams. Namedeca-(unit)hecto-(unit)kilo-(unit)mega-(unit)giga-(unit)tera-(unit) SymboldahkMGT Factor 10 0 10 1 10 2 10 3 10 6 10 9 10 12
How to use the SI System’s “Base 10”. Factors < 1 Example A fly’s wings are 23/1,000,000 meters thick. In this case, a better way to represent the fly’s wing thickness would be to represent it in terms of micrometers. Therefore, the fly’s wings are 23 micrometers thick, which is equivalent to 23/1,000,000 meters. Namedeci-(unit)centi-(unit)milli-(unit)micro-(unit)nano-(unit)pico-(unit) Symboldcm µ np Factor 10 0 10 -1 10 -2 10 -3 10 -6 10 -9 10 -12
Note: There are more metric prefixes beyond those listed.
Metric System vs. English System of Units – Table of Conversions Common Length Conversions Common Mass Conversions
English System The English System of Units, or Imperial System, isn’t as ubiquitous as the metric system, but still used today, mostly in the building industry. It isn’t as convenient as the metric system, and its conversions are more difficult to calculate.
History and Progression of English Values for Mass
As you can see, the metric system, or SI system, is much more convenient for conversions between values of various magnitudes.