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Section 8.1

Basic Terms and

Conversions Within the

Metric System

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What You Will Learn

SI SystemU.S. Customary SystemBasic UnitsHow to convert form one unit to another

8.1-2

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SI System and U.S. Customary System Most countries of the world use the Systéme international d’unités or SI system.The SI system is referred to as the metric system in the United States.Two systems of weights and measures exist side by side in the United States today, U.S customary system and the metric system.

8.1-3

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Advantages to Using the Metric SystemThe metric system is the worldwide accepted standard measurement system.There is only one basic unit of measurement for each physical quantity.The SI system is based on the number 10, allowing less need for fractions.

8.1-4

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Basic Terms

a little more than a quart

volumelliter

about 2.2 pounds

masskgkilogram

a little more than a yard

lengthmmeter

Comparison to Customary

Common Use

AbbrevMetric Term

8.1-5

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Metric Prefixes

1/1000 of base unit

mmilli1/100 of base unitccenti1/10 of base unitddecibase unit10 × base unitdadeka100 × base unithhecto1000 × base unitkkilo

MeaningSymbolPrefix

8.1-6

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Changing Units within the Metric System

To change from a smaller unit to a larger unit move the decimal point in the original quantity one place to the left for each larger unit of measure until you obtain the desired unit of measure.

8.1-7

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Changing Units within the Metric System

To change from a larger unit to a smaller unit, move the decimal point in the original quantity one place to the right for each smaller unit of measure until you obtain the desired unit of measure.

8.1-8

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Changing Units within the Metric System

Measure of length

kilometer hectometer dekameter

Symbol km hm dam

Number of meters

1000 m 100 m 10 m

Measure of length

meter decimeter centimeter millimeter

Symbol m dm cm mm

Number of meters

1 m 0.1 m 0.01 m 0.001 m

8.1-9

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Example 1: Changing Units

Convert 293.7 m to km.

SolutionMeters is a smaller unit than

km. Move the decimal 3 places to the left,

293.7 m = 0.29376 km.

8.1-10

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Example 1: Changing Units

Convert 14 g to cg.

SolutionGram is a larger unit than

centigram. Move the decimal point 2 places to the right

14 g = 1400 cg

8.1-11

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Example 1: Changing Units

Convert 0.76 l to ml.

SolutionLiter is a larger unit than

milliliter. Move the decimal point 3 places to the right,

0.76 l = 760 ml

8.1-12

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Example 1: Changing Units

Convert 240 dal to kl.

SolutionDecaliter is a smaller unit than

kiloliter. Move the decimal point 2 places to the left,

240 dal = 24.0 kl

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Example 2: Two More ConversionsConvert 502 mm to hectometers.

SolutionMillimeter is a smaller unit than

hectometer. Move the decimal point 5 places to the left,

502 mm = 0.00502 hm

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Example 2: Two More ConversionsConvert 6.34 dam to decimeters.

SolutionDekameter is a larger unit than

decimeter. Move the decimal point 2 places to the right,

6.34 dam = 634 dm

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Example 4: Comparing LengthsArrange in order from smallest to largest lengths: 3.4 m, 3421 mm, and 104 cm.

SolutionConvert all lengths to mm3.4 m = 3400 mm3421 mm104 cm = 1040 mmFrom smallest to largest:104 cm, 3.4 m, 3421 mm

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