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

THE METRIC SYSTEM

Edited by P. StewartEdited 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 Measurementaka: the metric system

All measurements REQUIRE a number AND All measurements REQUIRE a number AND a unit.a unit.

Scientists use SI units.Scientists use SI units. SI=International System of UnitsSI=International System of Units SI is a revised version of the older metric SI is a revised version of the older metric

systemsystem

Why is it useful for scientists to stick with Why is it useful for scientists to stick with one system?one system?

Base Units

Quantity Unit Symbol

Length Meter m

Volume Liter l

Mass Gram g

Temperature Kelvin K

Time Second s

Prefixes

Prefixes tell you how much of a base Prefixes tell you how much of a base unit you have. For example, a kiloliter unit you have. For example, a kiloliter means 1000 liters because kilo- means means 1000 liters because kilo- means 1000.1000.

Unit abbreviations come from the Unit abbreviations come from the combination of the prefix abbreviation combination of the prefix abbreviation and the base unit abbreviation. For and the base unit abbreviation. For example, a kiloliter is abbreviated kl. example, a kiloliter is abbreviated kl.

PrefixPrefix SymbolSymbol MeaningMeaning

giga-giga- GG billion (10billion (1099))

mega-mega- MM million (10million (1066))

kilo-kilo- kk thousand (10thousand (1033))

deci-deci- dd tenth (10tenth (10-1-1))

centi-centi- cc hundredth (10hundredth (10-2-2))

milli-milli- mm thousandth (10thousandth (10-3-3))

micro-micro- millionth (10millionth (10-6-6))

nano-nano- nn billionth (10billionth (10-9-9))

Why are prefixes useful?

Conversion Factors

Conversion factors are used to convert from Conversion factors are used to convert from one unit of measurement to anotherone unit of measurement to another

A ratio of equivalent measurementsA ratio of equivalent measurements

3/3 = ?3/3 = ?

67/67 = ?67/67 = ?

x/x = ?x/x = ?

1 meter/1 meter = ?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)

Kilo1000units

Hecto100units

Deka10

unitsBasic Unit Deci

0.1units

Centi0.01units

Milli0.001units

To convert to a smaller unit, movedecimal point to the _____ or

multiply.

To convert to a larger unit, movedecimal point to the ______ or divide

How can you remember the units in order?

How can you remember the units in order? King Henry died King Henry died

Monday drinking Monday drinking chocolate milk!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.


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


.15 L = __________ ml


.15 L = __________ ml150

Precision & Accuracy

PrecisionPrecision: a gauge of how exact a : a gauge of how exact a measurement ismeasurement is

The precision of a calculated answer is The precision of a calculated answer is limited by the least precise measurement in limited by the least precise measurement in the calculation.the calculation.

AccuracyAccuracy: the closeness of a measurement : the closeness of a measurement to the actual value of what is being to the actual value of what is being measuredmeasured

Top left: precise and Top left: precise and accurateaccurate


Bottom left: precise but Bottom left: precise but NOT accurateNOT accurate



Top Right: accurate but Top Right: accurate but NOT preciseNOT precise



Top Right: accurate but Top Right: accurate but NOT preciseNOT precise

Bottom Right: Neither Bottom Right: Neither accurate nor preciseaccurate nor precise

Measuring Temperature

Thermometer = measures temperatureThermometer = measures temperature

What are units of temperature you are What are units of temperature you are familiar with?familiar with?







Farenheit? Farenheit?




Farenheit? Farenheit? Celcius?Celcius?



What are units of temperature you are familiar What are units of temperature you are familiar with?with?

Farenheit? Farenheit? Celcius?Celcius? The news station uses which one to report the The news station uses which one to report the

weather?weather?

Celsius & Fahrenheit

ooC = 5/9(C = 5/9(ooF – 32F – 32oo))

ooF = 9/5(F = 9/5(ooC) + 32C) + 32oo

Kelvin

SI Base unit for temperature is the kelvin (K).SI Base unit for temperature is the kelvin (K).

0 K is the lowest possible temperature that 0 K is the lowest possible temperature that can be reached. can be reached.

0 K = -273.15 0 K = -273.15 ooC C

To convert: K = To convert: K = ooC + 273C + 273

Scientific Notation

Why is it useful?Why is it useful?

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

For example…

really really BIG numbers:really really BIG numbers:300,000,000 m/s = 3.0 x 10300,000,000 m/s = 3.0 x 1088 m/s m/s

The exponent, 8, tells you how many places to the The exponent, 8, tells you how many places to the right to move the decimal pointright to move the decimal point

really really SMALL numbers:really really SMALL numbers:0.00086 m/s = 8.6 x 100.00086 m/s = 8.6 x 10-4-4 m/s m/s

The exponent,-4, tells you how many places to the The exponent,-4, tells you how many places to the left to move the decimal pointleft to move the decimal point

So why is it useful?

Math with Scientific Notation

Multiplying: multiply the numbers and add Multiplying: multiply the numbers and add the exponents.the exponents.

Dividing: divide the numbers and subtract Dividing: divide the numbers and subtract the exponents.the exponents.

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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