# Topic The Metric System Do Now Calculate the

• Slides: 15

Topic: The Metric System Do Now: Calculate the volume of Fe. What element is Fe? mass of Fe(s) = 15. 9 g density of Fe(s) = 7. 87 g/cm 3

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

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

Systeme International (SI) • based on metric system • invented in 1790* • Larger & smaller multiples of each unit related by powers of 10 • prefixes *updated every few years (particularly in in 1960 and 1991)

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)

Kids Have Dropped Dead Converting Metric

Ladder Method 1 2 KILO 1000 Units HECTO 100 Units 3 DEKA 10 Units Meters Liters Grams DECI 0. 1 Unit How do you use the “ladder” method? 1 st – Determine your starting point. 2 nd – Count the “jumps” to your ending point. 3 rd – Move the decimal the same number of jumps in the same direction. CENTI 0. 01 Unit MILLI 0. 001 Unit 4 km = _____ m Starting Point Ending Point How many jumps does it take? 4. __. __. = 4000 m 1 2 3

Prefixes in the SI System Prefix Symbol Value Power Use Giga G 1, 000, 000 109 Gigabyte Mega M 1, 000 106 Megamillion Kilo deci k d 1, 000 0. 1 103 10 -1 kilometer centi c 0. 01 10 -2 centimeter milli m 0. 001 10 -3 millimeter micro 0. 000001 10 -6 micrometer nano n 0. 00001 10 -9 nanometer decimeter

Fundamental or Base units • The SI system has 7 fundamental units • All other units of measurement can be derived from these base units • You already know 4. What are they?

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

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

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

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…

Prototype kilogram stored in vault in France

So…. Why is the SI more efficient then the US system?