Thinking Like an EngineerStephan, Bowman, Park, Sill, OhlandCopyright 2013 Pearson Prentice-Hall, Inc.

Metric System & Other Units

Thinking Like an Engineer 2e

Dimensions & Base Units

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Dimensions versus Units Dimension: Unit:

measurable propertyspecific value used to count an amount of measurable property

For example: Dimension Units

Length meters fathom

inches miles

feet yardDimensions & Base Units

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SI Units Metric system or MKS system Meter Kilogram Second

Seven fundamental dimensions Seven base units Dimension All others derivedElectric currentLight intensity

SI Unit

Ii N M L T

amperecandela mole kelvin kilogram meter second

Acd mol K kg m s

SI system Based on power of 10 Uses named prefixes

Amount Temperature Mass Length Time

Notation RulesThinking Like an Engineer 2e

Dimensions & Base Units

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Systems of Units MKS system (SI Units)

Meter Kilogram Second Feet Pound-mass Second

AES (American Engineering System)

USCS (United States Customary Units)"English" units Feet Slug SecondDimension Length Mass Time Relative Temperature Absolute TemperatureThinking Like an Engineer 2e

SI (MKS) meter [m] kilogram [kg] second [s] Celsius [C] kelvin [K]

AES (American) foot [ft] pound-mass [lbm] second [s] Fahrenheit [F] Rankine [R]

USCS (English) foot [ft] slug second [s] Fahrenheit [F] Rankine [R]Dimensions & Base Units

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Accepted Non-SI UnitsSome units are accepted for common use with SI units: ngstrom electron volt hour liter minute year

astronomical unit atomic mass unit (or dalton) bar day degree

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Dimensions & Base Units

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What is expected of you Identify a quantity as a dimension or a unit List the seven fundamental dimensions and their abbreviation List the seven base SI units, their abbreviations, and the matching fundamental dimensions Express units correctly using the official SI rules Express quantities using correct SI prefixes

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Dimensions & Base Units

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