The Metric System Simple & Consistent Chapter 2, pages

Measurement up to 1790: Not a pretty picture! standardMeasurement requires a standard and until about the 1790’s every region had it’s own standards.

Standards “A standard is something that is used as a comparison for measuring. available for everyone a standard should be something in nature that is the same all over the earth –The standard must be available for everyone to use when checking measurements. This means a standard should be something in nature that is the same all over the earth. never vary –The standard must never vary.“ Source =

JOHN QUINCY ADAMS - Report to the Congress, 1821 “Weights and measures may be ranked among the necessaries of life to every individual of human society. They enter into the economical arrangements and daily concerns of every family. They are necessary to every occupation of human industry; to the distribution and security of every species of property; to every transaction of trade and commerce; to the labors of the husbandman; to the ingenuity of the artificer; to the studies of the philosopher; to the researches of the antiquarian; to the navigation of the mariner, and the marches of the soldier; to all the exchanges of peace, and all the operations of war.”

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

Basic Standard = Earth 1.The unit of length was to be a portion of the Earth's circumference.

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

Ease of Use - Calculations multiplying or dividing the basic units by factors of 10 3.Larger and smaller units are created by multiplying or dividing the basic units by factors of 10.

Ease of Use - Names prefixes 3.Larger & smaller multiples of each unit named by a series of prefixes relating them to the base unit.

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

Smaller & Larger Units 1/10 of a meter = decimeter 1/100 of a meter = centimeter 1/1000 of a meter = millimeter 10 meters = dekameter 100 meters = hectometer 1000 meters = kilometer

What is a Liter? The Liter is defined as a cube measuring 10 centimeters on each side, or 1000 cm 3. So, the Liter is based on the meter, which is based on the Earth. 10 cm

What is a kilogram? 10 cm The mass of 1 Liter of water at 4°C. Why water? So, the kilogram is based on the Liter, which is really based on the meter, which is really based on the Earth.

Prototype kilogram in France. Tiger

Jefferson Proposed a decimal-based measurement system for the United States. Didn’t come up with the prefix idea and his system had too many names.

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

Systeme International (SI) Based on the 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 in 1960.

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

Derived Units Combinations of fundamental units Many, many derived units Examples: –Speed or meters/second –Area or Length X Width –Volume or Length X Width X Height –Density or Mass / Volume

QuantityNameAbbreviation Lengthmeterm Masskilogramkg TemperaturekelvinK Timeseconds Luminous Intensity candelacd Electric Current ampereA Amount of Substance Molemol 7 Fundamental Quantities of SI

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

What is a kelvin? The kelvin is defined in terms of water & absolute zero. 0 K = Absolute zero. BP of H 2 O = 100  C = 373 K FP of H 2 O = 0  C = 273 K

What is a mole? The amount of substance which has as many elementary particles as there are atoms in kilogram of carbon-12.

PrefixSymbolValueFactorUse GigaG 1,000,000, Gigabyte MegaM1,000, Megamillion Kilok1, kilometer decid decimeter centic centimeter millim millimeter micro  micrometer nanon nanometer Prefixes in the SI System

Prefixes The prefixes can be used with all 7 fundamental units! meter –Kilometer liter –Milliliter gram –Centigram second –Microsecond kelvin –Nanokelvin