MeasuremenMeasurementsts

The Metric system was developed in France during the Napoleonic reign of

France in the 1790's.

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“Weights and measures may be ranked among the necessaries

of life to every individual of human society…They are

necessary to every occupation of human industry.... The knowledge of them, as in

established use, is among the first elements of education...”

JOHN QUINCY ADAMS - Report to the Congress, 1821

Which other countries, besides Which other countries, besides the U.S., do the U.S., do notnot use the metric use the metric

system?system?According to a survey taken According to a survey taken

many years ago, the only other many years ago, the only other countries that have countries that have notnot

officiallyofficially adopted the metric adopted the metric system are system are LiberiaLiberia (in western (in western

Africa) and Myanmar (also Africa) and Myanmar (also known as known as BurmaBurma, in Southeast , in Southeast

Asia).Asia).

STAT

FACT

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Accurate Measurements

•Be sure we can compare our measurements to other people.

•Scientists make repeatedmeasurements to increase the

validityand reliability of the results.

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•Accurate=how close the measurement is to the actual

measurement.

Accuracy vs. precisionAccuracy vs. precisionPrecision:Precision:

When taking When taking the same the same measurement measurement over and over over and over you get the you get the same results.same results.

Accuracy:Accuracy:

How close your How close your results are to results are to the TRUE/REAL the TRUE/REAL resultsresults

YOU CAN BE

PRECISE BUT

STILL BE

WRONG.

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• A Measurement system 1.must be agreed upon and

2.cannot change Ex: The foot.

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• Scale units• Metric system

attempted to do away with the confusing multiplicity of measurement scales by reducing them to a few fundamental ones.

Le Systeme Le Systeme Internationale Internationale d’Unites (SI)d’Unites (SI)

•1960•Based on Metric System

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StandardsStandards•Exact quantity that people

agree to use for a certain measurement.

•Ex: The meter•The speed that light travels in a

vacuum 1/299 792 458 of a second.

•Why….This seems CRAZY!!!•The meter Clip

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Another Example of a Standard …..The kilogram

The official kilogram, made of platinum-iridium, remains in France at the International Bureau of Weights and Measures

Clip

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Le Systeme Internationale Le Systeme Internationale d’Unites (SI)d’Unites (SI)

•English: International System of Units

•Each measurement has a base unit.

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SI SystemBased on multiples of ten.

Examples of base units•Length

– Meter•Mass

– Gram•Volume

– Liter•Time

– Second

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•Temperature-Kelvin

•Energy-Joule

•Electric Current

-Ampere

Prefixes• Prefixes are used with the base units to Prefixes are used with the base units to

indicate what multiple of ten should be used.indicate what multiple of ten should be used.

• The most common prefixes are:The most common prefixes are:

Prefix-Prefix- Symbol Multiple Symbol Multiple Kilo-Kilo- kk 1,0001,000Hecto-Hecto- hh 100100Deca-Deca- DD 1010Deci-Deci- dd .1.1Centi-Centi- cc .01.01Mili-Mili- mm .001.001

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BASE BASE UNITUNIT

Metric ConversionsMetric Conversions• A conversion is changing A conversion is changing

the way you state the the way you state the same amount!same amount!

• Ex: 1 dollarEx: 1 dollar– 4 quarters, 100 pennies, 4 quarters, 100 pennies,

10 dimes10 dimes• 1meter = 100centimeters1meter = 100centimeters• Simply move your Simply move your

decimal point.decimal point.

Convert the Following

1)65ml=_____L2)3948g=_____kg3)389.59m= ______km4)0.03748 mg=_____kg (use Sci. Not.)

5)89304µg= _______gScientific Notation: a method of writing, or of displaying real numbers as a decimal number

between 1 and 10 followed by an integer power of 10

Laboratory Laboratory

Apparatuses Apparatuses

for making for making

MeasurementsMeasurements

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Distance

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Meter StickMeter Stick

•1m = 100 1m = 100 CentimetersCentimeters

•1m = 1000 1m = 1000 millimetersmillimeters

1cm = 10 mm

Length

Distance

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Each line on the meter stick is a millimeter.

Meter StickMeter Stick 16

The last digit in all measurements is an estimate digit.

Amount of matter in an object

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Triple Beam BalanceGrams

300 +70 +3.31

=373.31g

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Space occupied

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Lengthwidth

Height

Length Length xx Height Height xx Width =Volume Width =Volume

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Graduated Cylinder Graduated Cylinder

Volume•Space an object occupies

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Kinetic Energy

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TemperatureFahrenheit vs. Celsius vs.

Kelvin

1742, Anders Celsius (1701-1744) 1714:Daniel

Gabriel Fahrenheit (1686-1736)

Lord Kelvin (1824-1907)

Superfridge

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Mass per unit Volume

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Derived UnitsDerived UnitsObtained by combining Obtained by combining

different unitsdifferent units..

ExEx:: Density Density

Density is the amount of Density is the amount of mass per unit volumemass per unit volume..

D D == m m//vv

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Remember... ....all measurement need a unit.

TYPES OF DATAQuantitative vs.

Qualitative•If the data collected involve observations without measurements or numbers, then it is referred to as qualitative data.

•Quantitative data involves numbers or measurements.

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Significant Figures

For measured numbers, significant figures relate the certainty of the measurement.As the number of significant figures increases, the more certain the measurement.

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The number of significant figures is the number of digits believed to be correct by the person doing the measuring.

Your answer cannot be more accurate than the equipment used to make the measurement.

The accuracy of the result is limited by the least accurate measurement.

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Sig Fig Rules• Nonzero digits are always significant • All final zeroes after a decimal point

are significant • Zeroes between two other

significant digits are always significant

• Zeroes used solely as placeholders are NOT significant

• Zeroes between a decimal point and a nonzero digit are significant.

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Examples• The significant zeroes in these

measurements are colored black and the insignificant zeroes are red. 

1) 0.0860             2) 1.0030         3) 0.000010203   4) 18,000                5) 18,000.00                 6) 0.10001      

Want to make it easier?????

Put it in Scientific Notation.

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PracticeHow many Sig Figs?

1. 234.87 _____2. 38302.00 _____3. 3900.00 _____4. 0.00045 _____5. 9394000.09 _____6. 479301820 _____7. 0.00034440 _____

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Arithmetic•When you perform any arithmetic

operation, it is important to remember that the result can never be more precise than the least precise measurement.

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Addition or Subtraction 1. Perform the operation.2. Round off the result to correspond to the

least precise value involved.  (fewest # of decimal places)

3. Example:24.686 m + 2.343 m + 3.21 m   =  30.239 m

**You will report the correct calculated  answer as

30.24 m.  

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1. Perform the operation.2. Round off the result to correspond

to the number with the LEAST number of significant figures.

3. Example: 3.22 cm x 2.1 cm  =  6.762 cm2   

**Reported answer: 6.8 cm2

Multiplication & Division Rules

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Practice1) 6.201 cm  + 7.4 cm  + 0.68 cm  + 12.0

cm  =  2) 1.6 km   +   1.62 m   +    1200 cm   =  3) 8.264 g   -   7.8 g   =   4) 10.4168 m   -   6.0 m    =  5) 12.00 m   +  15.001 m   =  6) 131 cm  x  2.3 cm   =  7) 5.7621 m  x  6.201 m   = 8) 20.2 cm  / 7.41 s   =  9) 40.002 g  / 13.000005 ml  = 

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Dimensional Analysis • Problem-solving method that uses the

fact that any number or expression can be multiplied by one without changing its value.

• Examples:– Convert 50.0 mL to liters. – How many centimeters are in 6.00 inches?– Express 24.0 cm in inches. – How many seconds are in 2.00 years?

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Temperature Conversion

• Examples on Notes.

K = º C + 273º C = (º F - 32) ÷

1.8

º C = K - 273 º F = 1.8 ºC + 32

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Answers   

1) -23 ºC            

2) 66 ºC            

3) 290 K            

4) 328 K             

5) 31.9 ºC                   

6) 230 ºF

Temperature Conversion