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The Metric System: History, Units, and Conversion Methods

Learn about the history of the metric system, its fundamental units, prefixes, and how to convert between different metric units.

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The Metric System: History, Units, and Conversion Methods

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  1. Topic: The Metric SystemDo Now: Calculate the volume of Fe. What element is Fe?mass of Fe(s) = 15.9 g density of Fe(s) = 7.87 g/cm3

  2. Measurement up to 1790:Not a pretty picture! Measurement requires standard and until 1790’s every region had own standard

  3. Standards • “standard: something used as comparison for measuring” • standard must: • be available for everyone to use to check measurements • be something in nature that is same everywhere • never vary

  4. Systeme International (SI) • based on metric system • invented in 1790* • Originally, earth-based standards • Volume & mass linked to length • Larger & smaller multiples of each unit related by powers of 10 *updated every few years (particularly in in 1960 and 1991)

  5. 3 Requirements 1790 – French Academy of Sciences created the metric system

  6. Smaller Units • 1/10 of a meter = decimeter (dm) • 1/100 of a meter = centimeter (cm) • 1/1000 of a meter = millimeter (mm) Larger Units • 10 meters = dekameter (dam) • 100 meters = hectometer (hm) • 1000 meters = kilometer (km)

  7. Prefix Symbol Value Power Use Giga G 1,000,000,000 109 Gigabyte Mega M 1,000,000 106 Megamillion Kilo k 1,000 103 kilometer deci d 0.1 10-1 decimeter centi c 0.01 10-2 centimeter milli m 0.001 10-3 millimeter micro  0.000001 10-6 micrometer nano n 0.000000001 10-9 nanometer Prefixes in the SI System Don’t copy…. where can you find?

  8. Fundamental or Base Units • Based on object or event in nature • The SI system has 7 fundamental units

  9. Quantity Name Abbreviation Length meter m Mass kilogram kg Time second s Temperature kelvin K Amount of Substance Mole mol Luminous Intensity candela cd Electric Current ampere A 7 Fundamental Quantities of SI

  10. Derived Units • Combinations of fundamental units • Examples: • Speed (meters/second) • Area (Length x Width) • Volume (Length x Width x Height) • Density (Mass / Volume)

  11. Prefixes • prefixes can be used with all 7 fundamental units! • Kilometer • Milliliter • Centigram • Microsecond • Nanokelvin

  12. 1790 - Jefferson • Proposed decimal-based measurement system for United States • Didn’t have prefix idea and system had too many names….and so we are stuck using feet, inches, cups, ounces, etc…

  13. What is a second? originally defined as 1/86,400th of average solar day Now: defined in terms of electron transitions in Cs-133 (Caesium – an element)

  14. What is a meter? OLD WAY1790: 1/10,000,000 th of distance from North pole to equator NEW WAY1983: distance light travels in vacuum in 1/299,792,458 th of second

  15. What is a Liter? • defined as cube measuring • 10 centimeters on each side • (1000 cm3) • Liter based on meter, which is based on Earth 10 cm 10 cm 10 cm

  16. What is a kilogram? defined as mass 1 Liter water at 4°C Why water? kilogram is based on liter, which is based on meter, which is based on Earth 10 cm 10 cm 10 cm

  17. Prototype kilogram stored in vault in France

  18. Kids Have Dropped Dead Converting Metric

  19. 1 2 3 MetersLitersGrams How do you use the “ladder” method? 1st – Determine your starting point. 2nd – Count the “jumps” to your ending point. 3rd – Move the decimal the same number of jumps in the same direction. Starting Point Ending Point __. __. __. 2 3 1 Ladder Method KILO1000Units HECTO100Units DEKA10Units DECI0.1Unit CENTI0.01Unit MILLI0.001Unit 4 km = _________ m How many jumps does it take? 4. = 4000 m

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