2. Metric System Simple & Consistent

3. Measurement up to 1790: not a pretty picture! standard measurement requires a recognizable standard for all but… until 1790’s every region had own standards

4. Standards “standard: something used as comparison for measuring” –standard must: available for everyonebe available for everyone to use be something in nature that is same everywherebe something in nature that is same everywhere never varynever vary

5. 1585 – Simon Stevin introduced use of decimals in Europe –to allow for parts of a whole predicted universal introduction of decimal coinage, measures and weights

6. 1670 – Gabriel Mouton based on size of earth1 st to propose decimal system of measurement based on size of earth Earth-based standard: 1  of longitude Earth is standard available to everyone! What an idea!

7. 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 (major changes in 1960 and 1991)

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

9. # 1 Basic Standard = Earth unit of length is portion of Earth's circumference

10. #2 Internal Consistency relatedunits for capacity (volume/space) and mass related to unit of length

11. #3 Ease of Use - Calculations multiplying or dividing basic units by factors of 10larger and smaller units created by multiplying or dividing basic units by factors of 10

12. Fundamental (Base) Units based on object/event in nature 7SI system has 7 fundamental units probably already know 4 of them any guesses as to which ones you know?

13. ABBREVIATIONUNITQUANTITY mmeterlength kgkilogrammass Kkelvintemperature ssecondtime cdcandela luminous intensity Aampere electric current molmole amount of substance 7 Fundamental Quantities of SI

14. Derived Units combinations of fundamental units examples: –speed –speed (meters/second) –area –area (length x width) –volume –volume (length x width x height) –density –density (mass / volume)

15. Ease of Use - Names larger & smaller multiples of same unit named by prefixes series of prefixes relating to base unit

16. smaller units 1/10 of meter = decimeter (dm) 1/100 of meter = centimeter (cm) 1/1000 of meter = millimeter (mm) larger units 10 meters = dekameter (dam) 100 meters = hectometer (hm) 1000 meters = kilometer (km)

18. UsePowerValueSymbolPrefix gigabyte 10 9 1,000,000,000 Ggiga megamillion 10 6 1,000,000Mmega kilometer 10 3 1,000kkilo decimeter 10 -1 0.1ddeci centimeter 10 -2 0.01ccenti millimeter 10 -3 0.001mmilli micrometer 10 -6 0.000001  micro nanometer 10 -9 0.000000001nnano Prefixes in the SI System

19. Prefixes used for all 7 fundamental units! meter –kilometer liter –milliliter gram –centigram second –microsecond kelvin –nanokelvin

20. 1790 - Jefferson proposed decimal-based measurement system for US cons: no prefixes & too many names

21. 1792 – U.S. Mint produced world’s first decimal currency (one dollar = 100 cents) 100 cents in dollar 4 quarters in dollar 10 dimes in dollar 20 nickels in dollar can see how this can be confusing: -names not related to each other -no consistency with parts of dollar

22. What is a meter? / 1790: 1/10,000,000 th of distance from North pole to equator / 1983: distance light travels in vacuum in 1/299,792,458 th of second

23. Liter What is a Liter? defined as cube measuring 10 centimeters on each side (1000 cm 3 ) 10 cm liter based on meter, which is based on Earth

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

25. second What is a second? originally defined as 1/86,400th of average solar day defined now in terms of electron transitions in Cs- 133

26. Kelvin What is a Kelvin? Kelvin is defined in terms of water & absolute zero 0 K = Absolute zero bp of H 2 O = 100  C = 373 K mp of H 2 O = 0  C = 273 K

27. mole What is a mole? amount any substance that has as many particles as # atoms found in 0.012 kg of carbon-12

28. kilogram prototype kilogram stored in vault in France