THE METRICTHE METRICoror

INTERNATIONAL INTERNATIONAL SYSTEM of SYSTEM of

MEASUREMENT (SI)MEASUREMENT (SI)

Scientists all over the world need Scientists all over the world need to ‘communicate’ with each other. to ‘communicate’ with each other. To do this easily, they use To do this easily, they use the same system of measurement. the same system of measurement.

This ‘system’ is This ‘system’ is known as the……known as the……

THE THE BASIC UNITBASIC UNIT OF THE ENTIRE OF THE ENTIRE

SI SYSTEM IS THESI SYSTEM IS THE

METERMETERThis fundamental unit is a bit This fundamental unit is a bit

longer than a yard.longer than a yard.

HOW TO MAKE LINEAR HOW TO MAKE LINEAR MEASUREMENTSMEASUREMENTSUSING SI UNITSUSING SI UNITS

To measureTo measure SMALLER SMALLER distances, the METER is distances, the METER is divided by a factor of ‘10’divided by a factor of ‘10’::

EXAMPLES:EXAMPLES:

– Decimeter (dm)Decimeter (dm) = 1/10 of a meter = 1/10 of a meter– Centimeter (cm)Centimeter (cm) = 1/100 of a meter = 1/100 of a meter– Millimeter (mm)Millimeter (mm) = 1/1000 of a meter = 1/1000 of a meter

A 3 day old tadpole is 1.2 centimeters in

length.

•To measure To measure LARGERLARGER

distances, the METER is distances, the METER is multiplied by multiplied by a factor of ‘10’a factor of ‘10’::

EXAMPLES:EXAMPLES:– Hectometer (hm) = 100 metersHectometer (hm) = 100 meters– Kilometer (km) = 1000 metersKilometer (km) = 1000 meters

THE BASIC UNITS USED FOR THE BASIC UNITS USED FOR MOST MOST LINEARLINEAR MEASUREMENT MEASUREMENT

ARE THESE FOUR……ARE THESE FOUR……

MILLIMETERSMILLIMETERS - very small - very small measurementsmeasurements

CENTIMETERSCENTIMETERS - small measurements- small measurements

METERSMETERS - large measurements- large measurements

KILOMETERSKILOMETERS - very large - very large measurementsmeasurements

SI units should SI units should NOTNOT be be ‘MIXED’‘MIXED’. .

That is, you would not write That is, you would not write ‘1 meter 21 centimeters’‘1 meter 21 centimeters’..

You should write You should write ‘1.21 ‘1.21

meters’meters’.. Also, linear measurements Also, linear measurements

should be written using should be written using DECIMALSDECIMALS. In most linear . In most linear

measurements, measurements, ONE DECIMAL ONE DECIMAL PLACEPLACE is sufficient. is sufficient.

Do Do NOTNOT use use FRACTIONSFRACTIONS! !

ONE LITERONE LITER

To obtain a unit of To obtain a unit of VOLUMEVOLUME in in the SI System, the SI System,

scientists took a empty box that scientists took a empty box that measured measured 10 cm. by 10 cm. by 10 10 cm. by 10 cm. by 10

cm.cm. and called this…… and called this……

AA LITER LITER is now a is now a common unit used by all common unit used by all

of us.of us.

AA LITER LITER is also used is also used with the prefix with the prefix ‘MILLI’‘MILLI’. .

Thus we have…… Thus we have……

a a MILLILITERMILLILITER to measure to measure very small volumes.very small volumes.

This is a ONE LITER This is a ONE LITER cube. 1/1000 th of it is cube. 1/1000 th of it is

1 MILLILITER1 MILLILITER..

This small This small cube iscube is

one one milliliter.milliliter.

This large This large cube is cube is oneone

literliter..

AA MILLILITER MILLILITER has the same has the same volume as volume as ONE ONE

CUBIC CENTIMETERCUBIC CENTIMETER..

Which means, milliliters (ml) Which means, milliliters (ml) and cubic centimeters (cc) can and cubic centimeters (cc) can be interchanged. be interchanged.

They both have the SAME They both have the SAME volume!volume!

125 cc’s125 cc’s

Now……to get a unit for Now……to get a unit for MASSMASS, ,

scientists tookscientists took 1 MILLILITER OF WATER1 MILLILITER OF WATER and made that mass equal toand made that mass equal to

1 GRAM1 GRAM!!

1 ml of 1 ml of water = 1 water = 1

gramgram

Again, Again, PREFIXESPREFIXES can be used in can be used in front of a front of a GRAMGRAM..

The common ones are……The common ones are……

MILLIGRAM - MILLIGRAM - very small very small massesmasses

KILOGRAMKILOGRAM - large masses - large masses

1 ‘carat’ 1 ‘carat’ equals equals

200 milligrams200 milligrams

Before we leave Before we leave MASSMASS units, units, we need to consider one other we need to consider one other

thing……thing……

MASSMASS and and WEIGHTWEIGHT are are NOT the same!NOT the same!

‘‘MASSMASS’’ is the amount of ‘stuff’ is the amount of ‘stuff’ in an object. in an object. It does NOT have anything to do It does NOT have anything to do

with with GRAVITYGRAVITY!!

MASS does NOT change !MASS does NOT change !It is measured in It is measured in GRAMSGRAMS..

It’s the It’s the SAMESAME everywhere in the everywhere in the universe.universe.

It does It does NOT NOT depend on gravity.depend on gravity.It is measured with a It is measured with a BALANCEBALANCE..

All these things’ masses All these things’ masses stay the same, stay the same, whereverwherever

they are!they are!

WEIGHT CHANGES !WEIGHT CHANGES !It depends on It depends on GRAVITYGRAVITY..It is usually measured in It is usually measured in

‘pounds’.‘pounds’.It is measured with a spring It is measured with a spring

scale.scale.

WEIGHT WEIGHT CHANGESCHANGES WITH WITH GRAVITYGRAVITY!!

You may be You may be ‘‘WEIGHTLESSWEIGHTLESS’’ but but you you still have MASSstill have MASS!!

and finally……and finally……THERE TWO THERE TWO TYPES OF MEASUREMENT IN TYPES OF MEASUREMENT IN

SCIENCESCIENCE

AN ‘UGLY’ AN ‘UGLY’ BABY?BABY?

YOU WEIGH 100 YOU WEIGH 100 POUNDS.POUNDS.

QUANTITATIVEQUANTITATIVEQUALITATIVEQUALITATIVE

EXAMPLES:EXAMPLES:• 70 degrees Celsius70 degrees Celsius• One inch of rainOne inch of rain• 6.2 centimeters6.2 centimeters• 640 miles640 miles• She scored 26 She scored 26

pointspoints

1.1. QUANTITATIVEQUANTITATIVE

MAKING MAKING ‘QUANTATIVE’ ‘QUANTATIVE’

MEASUREMENTS:MEASUREMENTS:

EXAMPLES:EXAMPLES:• It’s nice outIt’s nice out• It’s really hotIt’s really hot• It’s raining cats It’s raining cats

and dogs and dogs• He’s good He’s good

lookinglooking

2.2. QUALITATIVEQUALITATIVE

Whenever Whenever possible……possible……

QUANTITATIVEQUANTITATIVE is preferred is preferred

over QUALITATIVE over QUALITATIVE in SCIENCE!in SCIENCE!

A QUICK SI REVIEWA QUICK SI REVIEW• 1. THE BASIC SI UNIT OF LENGTH IS A _____.1. THE BASIC SI UNIT OF LENGTH IS A _____.• 2. 1/100th OF A METER IS _____.2. 1/100th OF A METER IS _____.• 3. THE ‘SI SYSTEM’ USED TO BE CALLED _____.3. THE ‘SI SYSTEM’ USED TO BE CALLED _____.• 4. A ____ IS USED TO MEASURE VERY LARGE4. A ____ IS USED TO MEASURE VERY LARGE

LINEAR DISTANCES.LINEAR DISTANCES.• 5. 1/1000th OF A GRAM IS ONE _____.5. 1/1000th OF A GRAM IS ONE _____.• 6. ‘AREA’ IS FOUND BY MULTIPLYING _____. 6. ‘AREA’ IS FOUND BY MULTIPLYING _____.

TIMES THE _____. TIMES THE _____. • 7. THE BASIC SI UNIT OF MASS IS A _____.7. THE BASIC SI UNIT OF MASS IS A _____.• 8. THE SMALLEST SI PREFIX USED DAILY IS8. THE SMALLEST SI PREFIX USED DAILY IS

THETHE _____._____. • 9.9. WEIGHT CHANGES WITH ______.WEIGHT CHANGES WITH ______.• 10.10. THE BASIC SI UNIT OF VOLUME IS A ______.THE BASIC SI UNIT OF VOLUME IS A ______.