Title: The Metric System
1The Metric System
2Measurement up to 1790Not a pretty picture!
- Measurement requires standard
- and until 1790s
- every region had own standard
3Standards
- 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
41585 Simon Stevin
- Introduced use of decimals in Europe
- Predicted universal introduction of decimal
coinage, measures and weights
51670 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!
6Systeme 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)
71790 French Academy of Sciences created the
metric system
8Basic Standard Earth
- 1.
- unit of length is portion of Earth's
circumference
9Internal Consistency
- 2.
- Units for capacity (volume or space) and mass
related to unit of length
10Ease of Use - Calculations
- 3.
- Larger and smaller units created by multiplying
or dividing basic units by factors of 10
11Fundamental or Base Units
- Based on object or event in nature
- The SI system has 7 fundamental units
- You already know 4. What are they?
127 Fundamental Quantities of SI
13Derived Units
- Combinations of fundamental units
- Examples
- Speed (meters/second)
- Area (Length x Width)
- Volume (Length x Width x Height)
- Density (Mass / Volume)
14Ease of Use - Names
- Larger smaller multiples of same unit named by
series of prefixes relating to base unit
15Smaller 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)
16Prefixes in the SI System
17Prefixes
- prefixes can be used with all 7 fundamental
units! - Kilometer
- Milliliter
- Centigram
- Microsecond
- Nanokelvin
181790 - Jefferson
- Proposed decimal-based measurement system for
United States - Didnt have prefix idea and system had too many
names
191792 U.S. Mint
- Produced worlds first decimal currency (one
dollar 100 cents)
20What 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
2110 cm
10 cm
10 cm
22defined 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
23What is a second?
originally defined as 1/86,400th of average solar
day
Now defined in terms of electron transitions in
Cs-133
24What 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
25What 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
26Prototype kilogram stored in vault in France