Science = the study of the world around us. Knowledge of
the physical or material world gained through observation
and experimentation.
The Nature of Science
• Scientific law versus theory:
– Scientific law: a summary of an
observed natural event.
– Scientific theory: a well tested,
possible explanation of a natural event.
The Way Science Works…
• Science involves critical thinking, or applying
logic and reason to observations and
conclusions.
• Observation vs. Inference
– Observation: descriptive of what you see,
hear, taste, feel, smell
– Inference: an assumption made as a result
of an observation (not always correct!!)
Variables and Controls
• A variable is anything that can change in an
experiment.
– Independent variable: The variable being changed
or controlled by the scientist.
– Dependent variable: The variable being measured
or observed by the scientist.
• A controlled experiment tests only one variable at a
time.
The Scientific Method:
A series of logical steps to follow in order to
solve problems.
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OBSERVE
FORMULATE A QUESTION
FORM A HYPOTHESIS
DESIGN AND CONDUCT AN EXPERIMENT
MAKE OBSERVATIONS
RECORD AND ANALYZE DATA
DRAW CONCLUSIONS
FORMULATE NEW QUESTIONS and
CONTINUE CYCLE
Making Measurements
• Measurements are made in this class using SI
units.
• LENGTH (m): distance between 2 points
• VOLUME (L): space occupied.
• MASS (kg): the amount of matter in an object.
• WEIGHT (N): the force with which gravity pulls on a
quantity of matter.
Precision vs. Accuracy
• Accuracy: the extent to which a
measurement approaches the true
value.
• Precision: the degree of exactness of
a measurement.
– A scale may be precise to the nearest
100th of a gram, or +/- 0.01g
increasing precision
Precision vs. Accuracy
increasing accuracy
Density = mass/volume
• Example 1:
– What is the density of water
if a 5 mL sample of water has
a mass of 5 g?
M
D
V
Example 2
– What is the mass of 10 mL of a liquid
that has a density of 3.76 g/mL?
d=m/v
m = dv
m = (3.76 g/mL)(10 mL)
m = 37.6 g
Coke vs. Diet Coke
• Which is less dense? Meaning which will
float in water?
• Coke or Diet Coke?
Calculations
• Calculate the density of each:
– A can of Coke has a volume of 355 mL and a
mass of 394 g (assuming that the weight of the
aluminum can is constant)
– A can of Diet Coke has a volume of 355 mL
and a mass of 355.1 g (assuming that the
weight of the aluminum can is constant)
WHY is Diet Coke less dense?
• There is less mass in the same volume (355
mL)
• Coke has 39 grams of sugar in it to sweeten
it (355 + 39 = 394 g)
• Diet Coke only needs 0.1 g of Nutra Sweet
to make is just as sweet as Coke
(355 + 0.1 = 355.2 g)
Temperature Conversions
• Temperature is a measure of the average
kinetic energy in a system.
• K = Kelvin
• oF = degree Fahrenheit
• oC = degree Celsius
Temperature Conversions
• K = oC + 273
• oF = (1.8 x oC) + 32
• oC = (oF – 32) / 1.8
Percentage Error
• Calculate this value in labs where the
accepted value is given.
accepted value  measured value
% error 
100
accepted value
Organizing Data
Data is organized and presented in tables, charts, and graphs.
Graph - visual representation of data
1) title
2) x and y axis labeled
3) units for both the x and y axis
4) scale is evenly and correctly spaced for data
5) legend when appropriate
Temperature Increase of a Beaker of Water
Temperature (K)
450
400
350
300
250
0
50
100
150
200
250
300
350
Time (sec)
LINE GRAPH: best for displaying
data that change.
– Independent Variable: x-axis
– Dependent variable: y-axis
400
Number of Death's per 100,000
People
Leading Causes of Death in 2000
350
300
300
233
250
200
150
107
98
100
57
50
0
Heart
Disease
Cancer
Diabetes
Accidents
Homicide
BAR GRAPH: useful when you want to compare
data for several individual items
Favorite Television Shows among Teens
1%
4%
20%
Friends
45%
Will and Grace
Frasier
Dawson's Creek
Other
30%
PIE CHART: ideal for displaying data that are
parts of a whole.
•Scientific Notation/Powers of 10
•Significant Figures
•Dimensional Analysis (Factor Label
Method)
Scientific Notation
Scientist use special notation to express
large or very small numbers.
very
Example I: 300,000,000 m/sec can be written as…
3 x 108 m/sec
Ex II: 1,007,000,000 sec can be written as…
1.007 x 109 sec
Ex III: 0.000 000 000 004 76 m can be written as…
4.76 x 10-12 m
Converting Metric Measurements
(PART 4 of Things to Know and Love)
To convert, move the decimal
place the number of stairs you
step on in the direction you are
traveling OR use dimensional
analysis.
kilo-
103
hecto-
102
deca-
101
Example:
3.75 km = ? mm
? = 3,750,000 mm
basic
unit
1
deci-
10-1
centi-
10-2
milli-
10-3
Video
•Powers of Ten
SIGNIFICANT FIGURES
• Scientists indicate the precision of measurements
by the number of digits they report = sig. figs.
– A value of 3.52 g is more precise than a value of
3.5 g
• All known digits plus one estimated digit
** the equipment used for a measurement will determine
the number of sig. figs.
Significant Figures
Atlantic - Pacific Rule:
Decimal Present: Count from the Pacific side
Decimal Absent: Count from the Atlantic side
Start counting at the first non-zero number and
count until you reach the end of the number
Ex. I: 3.00700
Decimal Present… Pacific (left)… 6 sig. figs.
Ex. II: 300,700
Decimal Absent… Atlantic (right)… 4 sig. figs.
(the last 2 zeros are PLACE HOLDERS)
REVIEW
Determine how many significant figures are in
each of the following measurements.
1)
2)
3)
4)
5)
6)
5
0.0034050 L
___________
5
33.600 m
___________
7500.0 g
___________
5
3
47,900 mm
___________
10
7,000,000,001 miles ___________
8.07 Hz
___________
3
(the first 3 zeros are PLACE
HOLDERS)
(the last 2 zeros are PLACE
HOLDERS)
More practice…
Round the following measurements off so that
they each contain 3 significant figures.
7) 366.2 L
8) 9,047,022 mg
9) 12.76 g
10) 999.9 J
___________
366 L
9,050,000
mg
___________
___________
12.8 g
1.00 x 103 J
___________
Notice this one must be in scientific
notation to have 3 sig. figs.
Significant Figures in Calculations
When multiplying and dividing, limit
and round to the least number of
significant figures in any of the
factors.
Example:
23.0 x 432 x 19 = 188,784 = 190,000
The answer is expressed as 190,000 or
1.9 x 105 since 19 has only two sig. figs.
Significant Figures in Calculations
When adding and subtracting, limit and
round your answer to the least number of
decimal places in any of the numbers
involved in the calculation.
Example:
123.25 + 46.0 +86.257 = 255.507 = 255.5
The answer is expressed as 255.5 since 46.0
has only one decimal place.
REVIEW
Perform the prescribed operations. Round your
answers to the proper # of sig. figs.
11) 36.57 m / 3.21 s =
___________
11.4 m/s
97.6 g
12) 41.376g + 13.3g + 42.9g=___________
76.2 m2
13) 5.67 m x 13.44 m
___________
14) (5.83 m/ 2.67 s) /2.1 s ___________
1.0 m/s2
60 V
15) 9.374 V x 6
___________
From now on, we will round all our answers
to the correct # of significant figures.
EXTRA REVIEW
• Using a calculator for EXPONONETS
(EE, EXP or x10x button)
– Example 1:
(5.02 x 10-3) x (6.3369 x 105)
= 3181.1238
*put in correct sig figs
= 3 sig figs
= 3180 or 3.18 x 103
Example 2 (use EE button!)
• (2.99 x 106) x (2.334 x 10-3) =
= 6978.66
• 3 sig figs
• 6980
DIMENSIONAL ANALYSIS
• How old are you in seconds?
– Go from number of years to number of seconds.
EX: 15 years old  _____ seconds old.
To do this, you need to use CONVERSION FACTORS (a ratio
of equivalent values used to express the same quantity in
different units)
Given Information: NOTETAKERS
General Format...
given
X
going to
coming from
=
GIVEN INFORMATION
1 kildurkin = 18 gallons
2 farkins = 1 kildurkin
1 hogshead = 63 gallons
1 barrel = 3.3 bushels
1 bushel = 8 gallons
Make a UNIT CONVERSION
MAP
Draw connections between the units in the
conversion factors…
(as you draw connections, check that
conversion factor off the list)
It’s kind of like a road map…
hogshead
gallons
bushel
barrel
kildurkins
farkins
Performing these
conversions is a lot like
going on a road trip.
ROAD TRIP!!!
Let’s say you want to travel from Oracle Jct to Casa Grande...
You must travel
through Tucson…
a two part trip.
Rule: You must stay on the roads &
REMEMBER SIG FIGS!!!
DO NOT GO OFF ROAD! 
Rule: You need a map. Sometimes the map can be in
your head. But, not at first. (show all work!!)
Let’s calculate
• Convert 14 gallons to kildurkins
• Convert 14 barrels to hogshead
• Convert 3.00 bushels to farkins
Now you try one. How many farkins is
3.00 bushels?
End Here
hogshead
gallons
kildurkins
farkins
Start Here
bushel
barrel
This will require 3
Conversions.
bushels
3.00 bushels
gallons
kildurkins
farkins
8.0 gallons 1.0 kildurkin 2.0 farkins
X
X
X
1.0 bushel
18 gallons
1.0 kildurkin
= 2.67 farkins
Wow! How
Cool Is That!
Handout: Fun Factor Label
• Handout
• Piece of lined paper (landscape format)
– Front is web for Distance and back is for Vol.
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Conversion Factors: change 10-10 to
Let’s do league  km  m  cm to start
You finish web, then do #3,6,7,9
Then do vol. web
Then finish questions #4, 5, 8, 10
FINISH FOR HW
1 x 10-10