MEASUREMENTFOUNDATIONS OF SCIENCE

ESSENTIAL QUESTIONS

WHAT IS A SCIENTIFIC MEASUREMENT? WHAT IS THE DIFFERENCE BETWEEN ACCURACY AND

PRECISION? WHAT IS A SYSTEMATIC METHOD OF CONVERTING

FROM ONE MEASUREMENT UNIT TO ANOTHER?

MEASUREMENT

A DETERMINATION OF THE AMOUNT OF SOMETHING

CONTAINS A NUMBER VALUE AND A UNIT

THE NUMBER IS USELESS WITHOUT A UNIT ATTACHED

TWO COMMON MEASUREMENT SYSTEMS

ENGLISH SYSTEM USED BY PEOPLE IN THE UNITED

STATES – INVOLVES UNITS SUCH AS MILES, FEET, CUPS, TEASPOONS, POUNDS, PINTS, QUARTS, GALLONS AND INCHES – lots of different relationships

INTERNATIONAL SYSTEM CALLED THE SYSTEM

INTERNATIONAL (SI UNITS) AS COINED BY THE FRENCH AND ADOPTED BY THE UNITED STATES IN 1960 – INVOLVES UNITS WHICH ARE ALL BASE 10 OR IN THE DECIMAL SYSTEM

COMPARE THE TWO SYSTEMS

ENGLISH SYSTEM – YARD STICK

1 YARD = 36 INCHES = 3 FEET SMALLEST DIVISION IS 1/32ND OF

AN INCH IN MOST CASES – A FRACTION OF AN INCH – TOUGH TO ESTIMATE THE MEASUREMENT SOMETIMES – based on fractions – ¼, 1/8, 1/16, etc.

INTERNATIONAL SYSTEM – METER STICK 1 METER = 100 CENTIMETERS = 1000

MILLIMETERS SMALLEST DIVISION IS A 1/10TH OF A

CENTIMETER OR ONE MILLIMETER – NOT A FRACTION, BUT 0.1 – EASIER TO ESTIMATE THE MEASUREMENT – based on decimals!!

COMMON SI UNITS

ACCURACY OF A MEASUREMENT

HOW CORRECT THE MEASUREMENT IS

IS IT CLOSE TO THE TARGET VALUE YOU ARE AIMING FOR?

DETERMINED BY CALCULATING A PERCENT ERROR FOR THE MEASUREMENT

CALCULATE THE PERCENT ERROR

If the density of an object is found to be 7.62 g/ml in the laboratory, what is the percent error if the reference density is 7.48 g/ml?

PRECISION OF A MEASUREMENT

HOW CLOSE THE REPEATED MEASUREMENTS ARE TO EACH OTHER

HOW CONSISTENT THE MEASUREMENTS ARE

FOR A MEASUREMENT, PRECISION IS REFLECTED IN HOW MANY SIGNIFICANT DIGITS ARE IN THE VALUE

PRECISION DEPENDS ON MEASURING INSTRUMENT

WHICH INSTRUMENT HAS BETTER PRECISION IN MEASURING THE VOLUME OF WATER?

MAKE THIS MEASUREMENT

In making a measurement, you are only allowed to estimate one digit.

All other digits are known for certain!!!

The digits known for certain and the one estimated digit are known as SIGNIFICANT DIGITS!!!!

ACTIVITY

You will be working with a partner to complete a packet in which you thoughtfully make several scientific measurements,

reporting all significant digits.

ACCURACY VS PRECISION

TIME

TWO WAYS TO THINK ABOUT TIME WHAT TIME IS IT? HOW MUCH TIME? (TIME

INTERVAL) TIME COMES IN MIXED UNITS YOU MAY NEED TO CONVERT

HOURS AND MINUTES INTO SECONDS

HOW MANY SECONDS DOES THE TIME INTERVAL REPRESENT?

DISTANCE

THE AMOUNT OF SPACE BETWEEN TWO POINTS

MEASURED IN UNITS OF LENGTH

THE METER IS THE BASIC SI UNIT

PREFIXES ARE ADDED TO REPRESENT EITHER MULTIPLES OF THE METER OR PARTS OF THE METER

1 MEGAMETER = 1,000,000 METERS

1 KILOMETER = 1000 METERS

100 CENTIMETERS = 1 METER

1000 MILLIMETERS = 1 METER

1,000,000 MICROMETERS = 1 METER

MASS

THE AMOUNT OF MATTER IN A SAMPLE

MEASURED IN THE SI UNIT OF KILOGRAM

1 MEGAGRAM = 1,000,000 GRAMS

1 KILOGRAM = 1000 GRAMS

100 CENTIGRAMS = 1 GRAM

1000 MILLIGRAMS = 1 GRAM

1,000,000 MICROGRAMS = 1 GRAM

VOLUME

THE AMOUNT OF SPACE TAKEN UP BY A SAMPLE

MEASURED IN SI UNITS OF LITERS

1 MEGALITER = 1,000,000 LITERS

1 KILOLITER = 1000 LITERS

100 CENTILITERS = 1 LITER

1000 MILLILITERS = 1 LITER

1,000,000 MICROLITERS = 1 LITER

COMPUTER LANGUAGE

METRIC PREFIXES

WHAT IS CONVENIENT IS THAT THE PREFIX INDICATES MAGNITUDE WHICH DOES NOT DEPEND UPON WHAT IS BEING MEASURED

FOR EXAMPLE, GIGA MEANS A BILLION OR 1,000,000,000 OR 109 WHETHER IT IS A GIGABYTE, GIGAGRAM, GIGASECOND, GIGALITER, OR GIGAMETER.

THE MAGNITUDE IS THE SAME, THE BASE UNIT REFLECTS WHETHER IT IS A MASS, VOLUME, TIME, COMPUTER STORAGE, OR DISTANCE MEASUREMENT.

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