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Chapter 1: IntroductionThe nature of science and

measurements

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Searching for objective data.Objectivity: The gathering of data or information without preconceived

ideas (prejudice) about how something is supposed to be.

Experiment: An organized procedure for gathering the data necessary to test a hypothesis.

Data Table: an organized method of displaying data.

Day Trucks Cars

Monday 15 25

Tuesday 12 30

Wednesday 16 22

Thursday 21 26

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Types of Information used in science

Data: measurable information learned by conducting an experiment, often in numerical form

Constant: factor whose value does not change.

Variable: any measurable quantity that may have different numerical values.

Control: factors in the experiment that are purposely left constant so that the result of other changes can be seen more clearly.

Models: representations of an object or problem developed by simplifying the object or eliminating several variables in order to study parts of an event.

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Line Graphs: are often used to describe how things change over a period of time.

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Are useful for comparing different things that occur at the same time.

Bar Graphs.

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Graphing Data: using a Line Graph.

Line Graph: points are plotted on the graph and joined together by a line.

Time, hoursVariable

TITLE:

2 4 6 8Scale

Best used to show how changes in value during the course of the experiment

Tem

p0 C

variable

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Measurement: the use of a pre-determined scale as a comparison to observe the size or the amount of something.

    Scientists in the 17-1800’s realized that accuracy in measurements was the key to uncovering truth about the universe.

    As better and more accurate measurement equipment became available, scientists were able to develop clearer understandings about the nature of our

universe.

 

Standard of Measure: A numerical quantity that everyone agrees to use, to represent the size or quantity of something.

Measurements:

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Customary (or English) system: developed over the centuries and is now used only in the U.S.

Metric System: based on units of 10 and developed in the mid 1700’s in Europe and is now used all over the world for commerce and manufacturing. 

International System SI: a simplified and version of the metric system adopted in the 1960’s to be the measurement system used in physics.

Systems of Measure: There are three primary measurement systems in use today. 

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Standard Base Units for measurements in both the Metric and SI systems

Length: the distance between two points measured in “Meters”.

Mass: the quantity of matter in an object, measured in “grams”

Time: the duration of an event measured in “seconds

Temperature: the amount of energy in a substance. Measured in degrees Celsius or degrees Kelvin.

Electrical Current: the number of electrical charges flowing through a wire in a second.

Volume: The amount of space occupied by an object or substance. measured in Liters or milliliters

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Derived Units: many of the units we work with will be combinations of the basic physical measurement units.

Example: m/s means meter divided by second or meter per second, a speed.

Example: g/cm3 means grams divided by cubic centimeters a density measurement

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Working with METRIC Measures:

Metric Prefixes: Letters preceding a metric unit like meter or gram that describe the size of the unit:

Commonly Used Prefixes.Prefix symbolmeaning multiple of base unitKilo k thousand 1000.Deci d tenth. 1.Centi c hundreth .01Milli m thousandth .001

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A single word, like 35.3 meters, 12.0 seconds, or 7.5 liters is always the base unit and its abbreviation is usually a single letter:

example: m for meter, g for gram, or s for second.

the prefix, when needed, gives the size and always comes first: example: kilometer, centimeter.

Abbreviations for measures with prefixes use 2 letters prefix first then the base unit.

example: mm the first letter m is for milli and the second m is for meter.

Metric Measurements and abbreviations

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O 1 2 3 4 5 6 7 8 9centimeters

O .01 .02 .03 .04 .05 .06 .07 .08 .09meters

O 10 20 30 40 50 60 70 80 90millimeters

Metric Rulers can be used for different measures

47 mm

4.7 cm

.047 m

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   Estimate the value between the two marks on either side of the object.

   The rightmost digit in your measurement should be an estimated digit.

0 10 20 3022.6 mm

0 10 20 3020 mm

22 mm

23 mm

Hints for making measurements:

   Read the scale from left to right.

   Start with the mark immediately to the left of the item you are measuring and note its

value.

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Rounding off numbers

Round 236.4 to the nearest ten.

Step 1: identify the digit in the tens’ place 236.422

Step 2: look at the digit 1 place to the right 236.422

If this digit is 5 – 9 round the tens place up

If this digit is 0 – 4 do not change the tens place

Step 3: Round the tens place up and use a zero as place holder for the 1’s place. 240 would be correct.

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Positive ExponentsExponent of 10 is the number of zero’s after 1Example: 103 = 1000

Zero Exponent: 100 = 1

Negative ExponentsExponent of 10 is 1 divided by the number.

Multiplying or a number times a power of ten

00101000

110 3 .

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Scientific Notation: Representing very large or small numbers using powers of ten.

Must be a number between 1 and 9 a decimal point and other digits followed by a power of ten.

Example: 23400 is represented by 2.34 x 10000 or 2.34 x 104

2 3400

Place decimal point here

Count these digits as the power of 10 = 4

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Example: 0.00456 is represented by 4.56 x 10–3

0.004 56

Place decimal point here

Count these decimal places as a negative exponent –3

Scientific Notation with negative exponents