DATA

the search for relationshipsthe search for relationshipsto to explainexplain and and predictpredict

the behavior of the universethe behavior of the universe

the science that dealsthe science that dealswith the relationshipwith the relationship

between between mattermatter and and energyenergy

There is no such thing asThere is no such thing asabsolute certaintyabsolute certainty

of a scientific claim.of a scientific claim.The validity of a scientific conclusion is always limited by:

• the experimentdesign, equipment, etc...

• the experimenterhuman error, interpretation, etc...

• our limited knowledgeignorance, future discoveries, etc...

Scientific Scientific LawLaw

Scientific Scientific TheoryTheory

Scientific Scientific HypothesisHypothesis

a statement describing a natural eventa statement describing a natural event

an experimentally confirmed explanationan experimentally confirmed explanationfor a natural eventfor a natural event

an educated guess (experimentally untested)an educated guess (experimentally untested)

developed in France in 1795developed in France in 1795a.k.a. “SI”a.k.a. “SI” -- International System of UnitsInternational System of Units

The U.S. was (and still is) reluctant to “go metric.”The U.S. was (and still is) reluctant to “go metric.”• very costly to changevery costly to change

•perception of “Communist” systemperception of “Communist” system•natural resistance to changenatural resistance to change

•American prideAmerican pride

The SI unit of:The SI unit of:•lengthlength is the is the metermeter, , mm

•timetime is the is the secondsecond, s, s

•massmass is the is the kilogramkilogram, , kgkg..

•electric chargeelectric charge is the is the CoulombCoulomb, C, C

•temperaturetemperature is the is the degree Kelvindegree Kelvin, , KK

•an amount of a substancean amount of a substance is the is the molemole, mol, mol

•luminous intensityluminous intensity is the is the candlecandle, , cdcd

• The The secondsecond is defined in terms of is defined in terms ofatomic vibrationsatomic vibrations of Cesium-133 atoms. of Cesium-133 atoms.

• The The metermeter is defined in terms of the is defined in terms of the speed of speed of

lightlight..

• The The kilogramkilogram is still defined by is still defined byan an official physical standardofficial physical standard..

““Derived units” are combinationsDerived units” are combinationsof these “fundamental units”of these “fundamental units”

Examples include:Examples include:

speed in speed in m/sm/s, area in , area in mm22, force in , force in kgkg..m/sm/s22,,

acceleration in acceleration in m/sm/s22, volume in , volume in mm33, energy in , energy in kgkg..mm22/s/s22

10101818 exaexa E E10101515 petapeta P P10101212 teratera T T 101099 gigagiga G G 101066 megamega M M 101033 kilokilo k k 101022 hectohecto h h 101011 dekadeka da da

10101818 attoatto a a10101515 femtofemto f f10101212 picopico p p 101099 nanonano n n 101066 micromicro 101033 milli milli m m 101022 centicenti c c 101011 decideci d d

Explore the metric system atExplore the metric system atlink1, , link2, , link3, and , and link4..

See definitions of metric units See definitions of metric units here..Click Click here to do conversions. to do conversions.

All measurements have some degree of uncertainty.All measurements have some degree of uncertainty.

Precisionsingle measurementsingle measurement - exactness, definitenessexactness, definiteness

group of measurementsgroup of measurements - agreement, closeness togetheragreement, closeness together

Accuracycloseness to the accepted valuecloseness to the accepted value

% error % error == accepted accepted -- observed observed

acceptedaccepted xx 100% 100%

1.1. All non-zero digitsAll non-zero digitsare significantare significant..

2.2. Final zeros after significant digitsFinal zeros after significant digitsare significantare significant..

3.3. Zeros between other significant digitsZeros between other significant digitsare significantare significant..

4.4. Leading zeros and final zerosLeading zeros and final zerosbefore the decimalbefore the decimalare not significantare not significant..

Operations with Significant DigitsOperations with Significant Digits

Addition and Subtractionround the sum or differenceround the sum or difference

to the least precise decimal placeto the least precise decimal place

Multiplication and DivisionMultiplication and Divisionround so that the product or quotientround so that the product or quotient

has a total number of significant digitshas a total number of significant digitsequal to the total number of significant digitsequal to the total number of significant digits

of the least precise quantity of the least precise quantity

Learn more aboutLearn more aboutsignificant digitssignificant digitshere and here.here and here.

Check your understandingCheck your understandinghere and here.here and here.