SI - System International The Metric System

How high is the ceiling?

1.0

0.1

How high is the ceiling?

Is the ceiling 5 glops high?

A. Yes B. No

What must be true of any

STANDARD

?

• Universally Understood • Repeatable

Old Standards • Digit • Cubit • Foot • Hands • Stone What is the problem with these Standards?

Metric System • Began in 1795 - French • Standardized - 1960 – What does this mean?

• Terms to Know – Fundamental / Derived – Quantity / Unit

Fundamental vs Derived • Fundamental Units – Base Unit which is defined to be Universally Understood and Repeatable – 7 Fundamental Units • Derived – A combination of more than 1 fundamental units – Examples: m/s; s 2 ; kgm / s 2 – Often given an equivalent expression: Newton, Watt, Joule

Quantities vs Units

Quantities

Amount or how much of a specific dimension Examples: Length, Mass, Volume, Density

Units

Describes the size in which a quantity is measured Examples: meter, foot, inch, mile second, hour, minute, millenium

7 Fundamental Units / Quantities • Length - meter • Mass - kilogram • Time - second • Electric Current - Ampere • Luminous Intensity - candela • Temperature - Kelvin • Amount of Substance - mole

Standard Definition - meter Old Definition 1 m is defined as 10 -7 of the distance from the North Pole to the Equator along a line through Lyon, France New Definition (1960) 1 m is defined as 1650763.63 times the wavelength of orange-red light from a Krypton-86 lamp Newest Definition (1982) 1 m is defined as the distance light travels in a vacuum in 1/2999792458 of a second

Standard Definition - second Old Definition 1 s is defined as 1/86400 of a mean solar day New Definition (1960) 1 s is defined as duration of 9192631770 cycles of the radiation from Cesium-133

Standard Definition - kilogram Old Definition 1 kg is defined as the mass of water at its densest (T= 4°C) which fills a volume of 1.0 liter New Definition (1960) 1 kg is defined as mass of a cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures near Paris QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Systems of Measurement • mks - Meter, Kilogram, Second • cgs - Centimeter, Gram, Second • fps - Foot, Pound, Second Note: These units are

fundamental

system.

in that What does it mean to be fundamental???

Systems of Measurement

System mks cgs fps Length

meter m

Mass

kilogram kg

Time

second s

Force Work Energy

Red = Fundamental

Systems of Measurement

System mks Length

meter m

Mass

kilogram kg

Time Force

second s kg m / s^2 Newton N

Work Energy

kg m^2/s^2 N*m Joule J

cgs fps

Red = Fundamental

Systems of Measurement

System mks cgs Length

meter m centimeter cm

Mass

kilogram kg gram g

Time

second s

Force

kg m / s^2 Newton N second s g cm / s^2 dyne

Work Energy

kg m^2/s^2 N*m Joule J dyne*cm erg

fps

Red = Fundamental

System mks cgs fps

Systems of Measurement

Length

meter m

Mass

kilogram kg

Time

second s

Force

kg m / s^2 Newton N

Work Energy

kg m^2/s^2 N*m Joule J centimeter cm foot ft gram g slug second s g cm / s^2 dyne second s pound lb p Red = Fundamental dyne*cm erg foot pound ft lb

Prefixes kilo Mega Giga Tera Peta

Large

k M G T P 10 10 10 10 10 3 6 9 12 15 centi milli micro nano pico femto

Smaller

c m µ f n p 10 -2 10 -3 10 -6 10 -9 10 -12 10 -15 Kids Hate Doing My Dumb Crazy Math