Introduction to the Metric System

1. Introduction to the Metric System Images found at http://flood.nhm.ac.uk/cgi-bin/dino/

2. SI (Metric) System of measurement • Definition: System of measurement invented by the French in 1790. Also called the International System of Units (SI system). • The SI system is the most used system of measurement on Earth (all countries except the U.S. use this system) • Common units: • Length: meter • Volume: liter • Mass: Kilogram

3. WHY DO WE USE THE METRIC SYSTEM? • Almost all other countries are using the metric system • Companies are refusing to buy products from the U.S. if not labeled in metric units • Scientists need a universal way to communicate data (SI Units)

4. WHAT DOES THE METRIC SYSTEM MEASURE? • The gram measures mass • The liter measures volume (usually liquids) • The meter measures length or distance

5. Length • The measured distance of an object, line or path. • The standard SI unit for length is the meter. • Note: there are 1000 millimeters in a meter and 100 centimeters in a meter.

6. Mass • Mass measures the amount of matter in an object (how much stuff is in an object). • The standard SI unit for mass is the kilogram. • The base unit gram is 1/1000th of a kilogram.

7. Volume • Volume measure the amount of space something takes up. • The standard SI unit for volume if the Liter. • The Liter is normally used for calculating the volume of liquids.

8. HOW BIG IS A METER? Definition: • 1983: The meter is the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second. • Note: There are 100 centimeters in a meter and 1000 millimeters in a meter.

9. Interesting previous definitions of meter: • 1889: a prototype made of an alloy of platinum with 10% iridium, at the temperature of melting ice. • 1799: A platinum prototype. • 1795: A brass prototype. • 1793: The meter was defined as 1/10 000 000 of the distance from an Earth pole to the equator.

10. HOW BIG IS A LITER? Definition: • 1964: The word liter may be employed as a special name for the cubic decimeter.

11. Previous definitionsof the Liter • 1901: The unit of volume, for high accuracy determinations, is the volume occupied by a mass of 1 kilogram of pure water, at its maximum density and at standard atmospheric pressure: this volume is called liter. • 1795: Liter is defined as a special name for the cubic decimeter.

12. HOW BIG IS A GRAM? • A gram is 1/1000 of a kilogram. • The kilogram is the standard unit of the metric system. • Definition of a kilogram: • A kilogram is equal to the mass of the international prototype of the kilogram kept at the Bureau International des Poids et Mesures. • 1 kilogram is equal to one cubic decimeter of pure water.

13. WHY DO WE USE METRIC PREFIXES? • In the metric system, larger and smaller units are constructed by adding prefixes to the appropriate base unit. • The prefixes indicate what power of ten the base unit was multiplied by to form the given unit.

14. Kilo Hecto Deka unit deci centi milli King Henry Died a death called measles Metric Prefixes • 1, 000 • 100 • 10 • 1 • 0.1 • 0.01 • 0.001

15. Stair Step Conversion Method:

16. Meter • Kilometer • Hectometer • Dekameter • meter • decimeter • centimeter • millimeter

17. Gram • Kilogram • Hectogram • Dekagram • gram • decigram • centigram • milligram

18. Liter • Kiloliter • Hectoliter • Dekaliter • liter • deciliter • centiliter • milliliter

20. Be aware the are many more prefixes for the SI system