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The Metric System

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The Metric System Simple & Consistent Measurement up to 1790: Not a pretty picture! Measurement requires standard and until 1790 s every region ... – PowerPoint PPT presentation

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Title: The Metric System


1
The Metric System
  • Simple Consistent

2
Measurement up to 1790Not a pretty picture!
  • Measurement requires standard
  • and until 1790s
  • 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 - Calculations
  • 3.
  • 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
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
17
Prefixes
  • prefixes can be used with all 7 fundamental
    units!
  • Kilometer
  • Milliliter
  • Centigram
  • Microsecond
  • Nanokelvin

18
1790 - Jefferson
  • Proposed decimal-based measurement system for
    United States
  • Didnt have prefix idea and system had too many
    names

19
1792 U.S. Mint
  • Produced worlds 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
10 cm
10 cm
10 cm
22
defined as mass 1 Liter water at 4C 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 0.012 kilogram of carbon-12

26
Prototype kilogram stored in vault in France
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