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THE METRIC SYSTEM Edited by P. Stewart

WHY DO WE USE THE METRIC SYSTEM? Almost all other countries are using the metric system Other countries’ 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)

APPROXIMATE CONVERSIONS BETWEEN METRIC & US LENGTH UNITS A meter is about the same length as a yard A meter is about three feet long A decimeter is about four inches long An inch is about 25 millimeters A foot contains about 30 centimeters A foot contains about 3 decimeters

WHAT DOES THE METRIC SYSTEM MEASURE? The gram measures mass or how much something weighs The liter measures volume which is used when measuring liquids The meter measures the length of an object or the distance from place to place

SI Units of Measurement aka: the metric system All measurements REQUIRE a number AND a unit. All measurements REQUIRE a number AND a unit. Scientists use SI units. Scientists use SI units. SI=International System of Units SI=International System of Units SI is a revised version of the older metric system SI is a revised version of the older metric system Why is it useful for scientists to stick with one system?

Base Units QuantityUnitSymbol LengthMeterm VolumeLiterl MassGramg TemperatureKelvinK TimeSeconds

Prefixes Prefixes tell you how much of a base unit you have. For example, a kiloliter means 1000 liters because kilo- means 1000. Prefixes tell you how much of a base unit you have. For example, a kiloliter means 1000 liters because kilo- means 1000. Unit abbreviations come from the combination of the prefix abbreviation and the base unit abbreviation. For example, a kiloliter is abbreviated kl. Unit abbreviations come from the combination of the prefix abbreviation and the base unit abbreviation. For example, a kiloliter is abbreviated kl.

PrefixSymbolMeaning giga-G billion (10 9 ) mega-M million (10 6 ) kilo-k thousand (10 3 ) deci-d tenth (10 -1 ) centi-c hundredth (10 -2 ) milli-m thousandth (10 -3 ) micro- millionth (10 -6 ) nano-n billionth (10 -9 )

Why are prefixes useful?

Conversion Factors Conversion factors are used to convert from one unit of measurement to another Conversion factors are used to convert from one unit of measurement to another A ratio of equivalent measurements A ratio of equivalent measurements 3/3 = ? 67/67 = ? x/x = ? 1 meter/1 meter = ?

To convert from one unit of measurement to another, multiply the number you want to change by the conversion factor that will change it

THE METRIC CONVERSION CHART (STAIRCASE METHOD) Kilo 1000 units Hecto 100 units Deka 10 units Basic Unit Deci 0.1 units Centi 0.01 units Milli 0.001 units To convert to a smaller unit, move decimal point to the _____ or multiply. To convert to a larger unit, move decimal point to the ______ or divide

How can you remember the units in order?

King Henry died Monday drinking chocolate milk! King Henry died Monday drinking chocolate milk!

TRY THIS USING THE STAIRCASE METHOD 1000 mg = ______ g Step 1: Determine if you are going to go up or down the ladder. Step 2: Determine how many steps there are from milligrams to grams. Step 3: Move the decimal point the amount of places that was determined in steps 1 & 2.

TRY THIS USING THE STAIRCASE METHOD 1000 mg = ______ g Step 1: Determine if you are going to go up or down the ladder. Step 2: Determine how many steps there are from milligrams to grams. Step 3: Move the decimal point the amount of places that was determined in steps 1 & 2. 1

TRY THIS USING THE STAIRCASE METHOD.15 L = __________ ml

TRY THIS USING THE STAIRCASE METHOD.15 L = __________ ml 150

Precision & Accuracy Precision: a gauge of how exact a measurement is Precision: a gauge of how exact a measurement is The precision of a calculated answer is limited by the least precise measurement in the calculation. The precision of a calculated answer is limited by the least precise measurement in the calculation. Accuracy: the closeness of a measurement to the actual value of what is being measured Accuracy: the closeness of a measurement to the actual value of what is being measured

Top left: precise and accurate

Bottom left: precise but NOT accurate

Top left: precise and accurate Bottom left: precise but NOT accurate Top Right: accurate but NOT precise

Top left: precise and accurate Bottom left: precise but NOT accurate Top Right: accurate but NOT precise Bottom Right: Neither accurate nor precise

Measuring Temperature Thermometer = measures temperature Thermometer = measures temperature What are units of temperature you are familiar with? What are units of temperature you are familiar with?

Measuring Temperature Thermometer = measures temperature Thermometer = measures temperature What are units of temperature you are familiar with? What are units of temperature you are familiar with?

Measuring Temperature Thermometer = measures temperature Thermometer = measures temperature What are units of temperature you are familiar with? What are units of temperature you are familiar with? Farenheit? Farenheit?

Measuring Temperature Thermometer = measures temperature Thermometer = measures temperature What are units of temperature you are familiar with? What are units of temperature you are familiar with? Farenheit? Farenheit? Celcius? Celcius?

Measuring Temperature Thermometer = measures temperature Thermometer = measures temperature What are units of temperature you are familiar with? What are units of temperature you are familiar with? Farenheit? Farenheit? Celcius? Celcius? The news station uses which one to report the weather? The news station uses which one to report the weather?

Celsius & Fahrenheit o C = 5/9( o F – 32 o ) o F = 9/5( o C) + 32 o

Kelvin SI Base unit for temperature is the kelvin (K). 0 K is the lowest possible temperature that can be reached. 0 K = -273.15 o C To convert: K = o C + 273

Scientific Notation Why is it useful? Why is it useful? Scientific Notation: a way of expressing a value as the product of a number b/t 1 and 10 and a power of 10. Scientific Notation: a way of expressing a value as the product of a number b/t 1 and 10 and a power of 10.

For example… really really BIG numbers: 300,000,000 m/s = 3.0 x 10 8 m/s The exponent, 8, tells you how many places to the right to move the decimal point really really SMALL numbers: 0.00086 m/s = 8.6 x 10 -4 m/s The exponent,-4, tells you how many places to the left to move the decimal point

So why is it useful?

Math with Scientific Notation Multiplying: multiply the numbers and add the exponents. Multiplying: multiply the numbers and add the exponents. Dividing: divide the numbers and subtract the exponents. Dividing: divide the numbers and subtract the exponents.

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