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The Metric System Catherine Le (Ilona Davies) The Harker School 2007-2008 Brief History of Measurement QuickTime™ and a Sorenson Video decompressor are needed to see this picture. 2 The Metric System QuickTime™ and a Sorenson Video decompressor are needed to see this picture. 3 SI Units of Measurement: Metric System Scientists all over the world use a set of measuring units called the International System of Units (SI). SI is a revised version of the metric system, which is based on multiples of 10. SI is built upon seven base units and many derived units. For example, the base unit for length is meter (m) and the derived unit for volume (length x length x length) is cubic meters (m3). 4 SI Base Units (Video Review) Length Volume Meter (m) Liter (L or l) Mass Gram (g) 5 SI Base Units http://www.onlineconversion.com/ Reference: http://physics.nist.gov/cuu/Units/index.html 6 Examples of SI Derived Units Quantity Unit Symbol Area square meter m2 Volume cubic meter m3 Speed meters per second m/s Acceleration meters per second squared m/s2 Force newton N = kg.m/s2 Energy joule J = kg.m2/s2 Pressure pascal Pa = kg/m.s2 Density Grams per cubic centimeter g/cm3 7 Metric System of Measurement Measurements must have a value and a unit (for example, 53 meters). A metric prefix indicates how many times a unit should be multiplied or divided by 10. For example, 1000 meters = 1 kilometer. The prefix “kilo-” tells us that we need to multiply km by 1000 to convert to m. A conversion factor is a ratio of equivalent measurements that is used to convert a quantity of one unit to another. To convert s to ms, you would multiply by a conversion factor of 1000 ms/1 s. 8 Some SI Prefixes Prefix Factor Prefix Example mega- 106 M Megameter (1 000 000 meters) kilo- 103 k Kilometer (1000 meters) hecto- 102 h Hectometer (100 meters) deka- 101 da Decameter (10 meters) 100 Meter (1 meter) deci- 10-1 d Decimeter (0.1 meters) centi- 10-2 c Centimeter (0.01 meters) milli- 10-3 m Millimeter (0.001 meters) micro- 10-6 µ Micrometer (0.000 001 meters) 9 Metric Conversions QuickTime™ and a Sorenson Video decompressor are needed to see this picture. 10 Metric Conversions QuickTime™ and a Sorenson Video decompressor are needed to see this picture. 11 Metric Stairs UP RULE Kilo Decimal Moves Left one place for each step you go up. Hecto Deca Base Unit (Meter Liter Gram) Deci Centi Milli Decimal Moves Right one place for each step you go down. DOWN RULE 12 Checkpoint! What is the numerical value of the following prefixes? Deci = ________________ Hecto = ________________ Milli = ______________ Deca = ________________ Kilo = ___________________ What is the unit of measurement for the following? Length = _________________ Volume = _________________ Mass = ________________ 13 Checkpoint! 1 km = ____________ m 1 m = ____________ cm 1 mm = ____________dm 1 dm = ____________ dam 1 liter = ____________ cm3 (Hint: 1mL = 1 cm3) 1 kg = ____________ g 14