1. The Metric System
Simple & Consistent

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. 1585 – Simon Stevin Introduced use of decimals in Europe
Predicted universal introduction of decimal coinage, measures and weights

5. 1670 – Gabriel Mouton
1st to propose decimal system of measurement based on size of earth
Earth-based standard: 1 of longitude
The earth is standard available to everyone! What an idea!

6. 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)

7. 1790 – French Academy of Sciences created the metric system
3 Requirements

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

9. Internal Consistency 2.
Units for capacity (volume or space) and mass related to unit of length

10. Ease of Use - Calculations3.
Larger and smaller units created by multiplying or dividing basic units by factors of 10

11. Fundamental or Base Units
Based on object or event in nature
The SI system has 7 fundamental units
You already know 4. What are they?

12. 7 Fundamental Quantities of SI
Abbreviation
Name
Quantity m
meter
Length kg
kilogram
Mass s
second
Time K
kelvin
Temperature
mol
Mole
Amount of Substance cd
candela
Luminous Intensity A
ampere
Electric Current

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

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

15. 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)

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

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

18. Jefferson
Proposed decimal-based measurement system for United States
Didn’t have prefix idea and system had too many names

19. 1792 – U.S. Mint
Produced world’s first decimal currency (one dollar = 100 cents)

20. 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

21. 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

22. 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

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

24. What is a Kelvin? Kelvin is defined in terms of water & absolute zero
0 K = Absolute zero
bp of H2O = 100C = 373 K
mp of H2O = 0C = 273 K

25. What is a mole?
amount of any substance that has as many elementary particles as the number of atoms found in kilogram of carbon-12

26. Prototype kilogram stored in vault in France