Js082.k12.sd.us



The Metric System

 

 

Important dates in the history of the modern metric system (S.I.):

1670  metric system originated on about this date. Gabriel Mouton, a French vicar

1790  Thomas Jefferson proposed a decimal-based measurement system for the United States.

1792  The U.S. Mint was formed to produce the world's first decimal currency (the U.S. dollar consisting of 100 cents).

1866  The use of the metric system made legal (but not mandatory) in the United States by the Metric Act of 1866 (Public Law 39-183).  This law also made it unlawful to refuse to trade or deal in metric quantities.

1975  The Metric Conversion Act of 1975 (Public Law 94-168) passed by Congress. The Act established the U.S. Metric Board to coordinate and plan the increasing use and voluntary conversion to the metric system. However, the Act was devoid of any target dates for metric conversion.

1979  BATF requires wine producers and importers to switch to metric bottles in seven standard [liter and milliliter] sizes.

1983  The meter is redefined in terms of the speed of light by the 17th CGPM, resulting in better precision but keeping its length the same.

1988  The Omnibus Trade and Competitiveness Act of 1988 amended and strengthened the Metric Conversion Act of 1975, designating the SI metric system as the preferred measurement system, and requiring each federal agency to be metric by the end of fiscal year 1992.

1991  President George Bush signed Executive Order 12770, Metric Usage in Federal Government Programs directing all executive departments and federal agencies implement the use of the metric system. The Executive Order is also available as an appendix to: Interpretation of the SI for the United States and Federal Government Metric Conversion Policy

1994  The Fair Packaging and Labeling Act (FPLA) was amended by the Food and Drug and Administration (FDA) to require the use of dual units (inch-pound AND metric) on all consumer products.

1996  As of July 1996 all surface temperature observations in National Weather Service METAR/TAF reports are now transmitted in degrees Celsius.

2001 April 09  U.S. Stock Exchanges changed to decimal trading. The Securities and Exchange Commission has ordered that all stocks must be quoted in dollars and cents rather than fractions by this date. The switch to decimal trading brought the U.S. in line with the rest of the world's major exchanges. This follows the change of the Canadian Stock Exchanges to decimal trading in 1996.

One of the principal advantages of the Metric System is its use of only one unit (standard of size) for each parameter (thing that is being measured). The metric units are interrelated in such a way that only five fundamental standards are necessary. These fundamental standards are identified with an * in the tables below.

The 5 Standard Metric Units

Second - time

Gram - mass

degrees Kelvin - temperature

Candle - light

Coulomb - electrical charge

MECHANICS

|Parameter: |Metric Unit |English Units |

|Time duration, delay |second * s |second, minute, hour, day |

|frequency |Hertz 1/s |cycle per second |

|length |Meter |inch, foot, yard |

|distance, displacement |1/299 792 458 light sec |rod, chain, furlong, mile |

| |m | |

|velocity, speed |meter per second |foot per second |

|rate of change of position |m/s |mile per hour, knot |

|acceleration |meter per second squared |foot per second squared |

|rate of change of velocity |m/s2 | |

|mass |gram * |ounce, pound, ton |

|quantity of material |g | |

|force |Newton |pound-force |

|push, pull, or weight |kg m/s2 | |

|impulse |newton second |pound-force second |

|force times time |kg m/s | |

|momentum |kilogram meter per second |pound foot per second |

|mass times velocity |kg m/s | |

|work, energy |joule (pronounced "jewel") |foot pound-force |

|force times distance |= one newton meter | |

| |kg m2/s2 | |

|power |Watt |foot pound-force per second |

|rate of doing work |= one joule per second |horsepower |

| |kg m2/s3 | |

|area |square meter |square foot, square yard |

|size of a surface |m2 |acre, square mile |

|pressure |Pascal |pound-force per square inch |

|force per unit area |newton per square meter kg/m s2 | |

|volume, capacity |cubic meter (stere) |pint, quart, gallon |

| |m3 |cubic foot, cubic yard |

|density, heaviness |grams per cubic centimeter |pounds per cubic foot |

| |g/cm3 | |

HEAT

|Parameter: |Metric Heat Unit |English Heat Unit |

|heat energy |joule, calorie, Calorie |British Thermal Unit |

| |1 cal = 4.186 joules | |

| |1 Cal = 4186 joules | |

|temperature change |kelvin * |Fahrenheit degree |

|temperature |degrees kelvin |degrees Fahrenheit |

|  |  |  |

[pic]

LIGHT

|Parameter: |Metric Light Unit |

|luminous intensity |candle * |

|luminous flux |lumen |

| |one candle produces 4 pi lumens |

|illumination |lux |

| |lumen per square meter |

|focus |diopter |

| |reciprocal meters |

|astronomical distance |parsec |

|  |  |

[pic]

ELECTRICITY & MAGNETISM (There are no English electrical units)

|Parameter: |Metric Electrical Unit |

|electric charge |coulomb * |

| |96,500 coul = 1 faraday = 1 mole of electrons |

|electromotive force (EMF) |volt (joule per coulomb) |

|capacitance |farad (coulomb per volt) |

|electric current |ampere (coulomb per second) |

|electric energy |joule (watt second) -- (newton meter) |

| |KWH = 3,600,000 joules |

|electric power |watt (joule per second) |

|electrical resistance |ohm (volt per ampere) |

|electrical conductivity |siemens (coulomb per joule) |

| |(ampere per volt) |

|electrical field strength |volts per meter |

|electromagnetic inductance |henry (pl. henrys) |

|magnetic field intensity |oersted (formerly the gauss) |

|magnetic flux |weber (108 maxwells) |

|magnetic flux density |tesla weber per square meter |

|magnetomotive force |gilbert |

Each physical quantity (length, mass, volume, etc.) is represented by a specific SI unit. That unit is made larger or smaller by addition of a prefix to the stem unit.

[pic]

Commonly used metric system units and symbols:

|Type of Measurement |Unit Name |Symbol |

|length, width, distance, thickness, girth, etc. |meter |m |

|mass (often called weight) |kilogram* |kg |

|mass (larger) |metric ton |t |

|time |second |s |

|temperature |degree Celsius** |°C |

|area |square meter |m2 |

|area (land) |hectare |ha |

|volume (liquid or other) |liter |L*** |

|volume (larger) |cubic meter |m3 |

|density |kilogram per cubic meter |kg/m3 |

|velocity |meter per second |m/s |

|velocity (autos) |kilometer per hour |km/h |

|force |newton |N |

|pressure, stress |kilopascal |kPa |

|energy |kilojoule |kJ |

|power |watt |W |

*The gram (g) is the stem unit to which other prefixes are added.

**The kelvin (K) is the SI base unit of thermodynamic temperature.

***The capital el (L) is preferred as the symbol for liter in the USA; however the lower case el (l) also is correct and is used in many metric countries.

Derived Units

|Force |Newton |N |kg m s-2 |

|Energy |joule |J |kg m2 s-2 |

|Power |watt |W |kg m2 s-3 |

|Frequency |hertz |Hz |s-1 |

|Charge |coulomb |C |A s |

|Capacitance |farad |F |C2 s2 kg-1 m-2 |

|Magnetic Induction |tesla |T |kg A-1 s-2 |

| [pic] |The Metric Prefixes |

 

|Prefix: |Symbol: |Magnitude: |Meaning (multiply by): |

|Yotta- |Y |1024 |1 000 000 000 000 000 000 000 000 |

|Zetta- |Z |1021 |1 000 000 000 000 000 000 000 |

|Exa- |E |1018 |1 000 000 000 000 000 000 |

|Peta- |P |1015 |1 000 000 000 000 000 |

|Tera- |T |1012 |1 000 000 000 000 |

|Giga- |G |109 |1 000 000 000 |

|Mega- |M |106 |1 000 000 |

|myria- |my |104 |10 000 (this is now obsolete) |

|kilo- |k |103 |1000 |

|hecto- |h |102 |100 |

|deka- |da |10 |10 |

|- |- |- |- |

|deci- |d |10-1 |0.1 |

|centi- |c |10-2 |0.01 |

|milli- |m |10-3 |0.001 |

|micro- |u (mu) |10-6 |0.000 001 |

|nano- |n |10-9 |0.000 000 001 |

|pico- |p |10-12 |0.000 000 000 001 |

|femto- |f |10-15 |0.000 000 000 000 001 |

|atto- |a |10-18 |0.000 000 000 000 000 001 |

|zepto- |z |10-21 |0.000 000 000 000 000 000 001 |

|yocto- |y |10-24 |0.000 000 000 000 000 000 000 001 |

   

Commonly used metric prefixes

|Prefix Name |Prefix Symbol |Prefix Value |

|giga |G |1 000 000 000 |109 |

|mega |M |1 million or 1 000 000 |106 |

|kilo |k |1 thousand or 1000 |103 |

|hecto |h |100 |102 |

|deka |da |10 |10 |

|  |  |  |  |

|deci |d |1/10 or 0.1 |10-1 |

|centi |c |1/100 or 0.01 |10-2 |

|milli |m |1/1000 or 0.001 |10-3 |

|micro |µ |1/1 000 000 or 0.000 001 |10-6 |

|nano |N |1/1 000 000 000 or 0.000 000 001 |10-9 |

[pic]

Some special relationships:

• 1 milliliter = 1 cubic centimeter

• 1 milliliter of water has a mass of approximately 1 gram

• 1 liter of water has a mass of approximately 1 kilogram

• 1 cubic meter of water has a mass of approximately 1 metric ton

Legal/official (exact) definitions of inch-pound units as set by U.S. law:

• 1 inch = 25.4 millimeters

• 1 pound = 453.592 37 grams

• 1 gallon = 3.785 411 784 liters

Note: In Canada the inch and the pound are defined identically, but 1 Canadian gallon = 4.546 09 liters.

Approximate conversion factors between inch-pound units and the International System of Units (SI):

• Multiply inches by 2.54 to get centimeters (this conversion factor is exact)

• Multiply feet by 0.305 to get meters

• Multiply miles by 1.6 to get kilometers

• Divide pounds by 2.2 to get kilograms

• Multiply ounces by 28 to get grams

• Multiply fluid ounces by 30 to get milliliters

• Multiply gallons by 3.8 to get liters

[pic]

Some baseline temperatures in the three temperature scales

|temperature |kelvins |degrees Celsius |degrees Fahrenheit |

|symbol |°K |°C |°F |

|boiling point of water |373.15 |100. |212. |

|average human body temperature |  |37. |98.6 |

|average room temperature |  |20. to 25. |68. to 77. |

|freezing / melting point of water / ice |273.15 |0. |32. |

|absolute zero |0. |-273.15 |-459.67 |

[pic]

Temperature conversions between the three temperature scales:

kelvin / degree Celsius conversions (exact):

• kelvins = degrees Celsius + 273.15

• degrees Celsius = kelvins - 273.15

degree Fahrenheit / degree Celsius conversions (exact):

• degrees F = degrees C x 1.8 + 32.

• degrees C = (degrees F - 32.) / 1.8

[pic]

A degree Celsius memory device:

There are several memory aids that can be used to help the novice understand the degree Celsius temperature scale.

One such nemoic is:

When it's zero it's freezing,

when it's 10 it's not,

when it's 20 it's warm,

when it's 30 it's hot!

Or, another one to remember:

30's hot

20's nice

10's cold

zero's ice

 

Examples of everyday item equivalences for metric units of length, mass, volume, and temperature

(Drawings excerpted from the book, Quick Guide to the Metric System, by Valerie Antoine, USMA Executive Director)

|Length: |[pic] |

|1 meter (1 m) | |

|1 centimeter (1 cm) |[pic] |

|1 kilometer (1 km) |[pic] |

|Mass: |[pic] |

|1 kilogram (1 kg) | |

|1 gram (1 g) |[pic] |

|Volume: |[pic] |

|1 liter (1 L or 1 l) | |

|1 milliliter (1 mL or 1 ml) |[pic] |

|Temperature: |[pic] |

|degree Celsius (°C) | |

[pic]

  Scientific Notation

 

Learn how to write numbers in scientific notation



 

More info



 

Temperature conversions (°C °F)

 

Sources:













................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download