Ch. 1 - The Nature of Science

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Ch. 1 - The Nature of Science

• Defining Science
• Problem-Solving
• Scientific Method
• Experimental Design

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A. Defining Science

• Pure Science
• research that adds to the body of scientific
  knowledge
• has no practical use
• Applied Science (Technology)
• the practical application of scientific
  knowledge

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A. Defining Science

• PURE
• human genetics
• polymer science
• atomic theory
• study of the human ear

• APPLIED
• DNA fingerprinting
• Lycra spandex
• nuclear weapons
• hearing aids

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A. Defining Science

• Life Science
• the study of living organisms
• Earth Science
• the study of Earth and space
• Physical Science
• the study of matter and energy
• chemistry physics

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B. Problem-Solving

• 1. Identify the problem.
• What do you know?
• What do you need to know?
• 2. Plan a strategy.
• Look for patterns.
• Break the problem into smaller steps.
• Develop a model.

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B. Problem-Solving

• 3. Execute your plan.
• 4. Evaluate your results.
• Did you solve the problem?
• Is your answer reasonable?
• Identify - Plan - Execute - Evaluate

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C. Scientific Method

• Hypothesis - testable prediction
• Theory - explanation of why
• based on many observations experimental results
• Scientific Law - prediction of what
• describes a pattern in nature

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C. Scientific Method

• Theories and laws are well-accepted by
  scientists, but...

THEY ARE NOT SET IN STONE!
They are revised when new information is
discovered.
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C. Scientific Method

• 1. Determine the problem.
• 2. Make a hypothesis.
• 3. Test your hypothesis.
• 4. Analyze the results.
• 5. Draw conclusions.

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C. Scientific Method

• 1. Determine the problem.
• When the Titanic sank, what happened to the
  water level on shore?
• 2. Make a hypothesis.
• The water level rose.
• The water level dropped.
• The water level stayed the same.

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C. Scientific Method

• 3. Test your hypothesis.
• How could we test our hypothesis?
• 4. Analyze the results.
• What happened during our test?
• 5. Draw conclusions.
• Was our hypothesis correct?
• Is further testing necessary?

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D. Experimental Design

• Experiment - organized procedure for testing a
  hypothesis
• Key Components
• Control - standard for comparison
• Single variable - keep other factors constant
• Repeated trials - for reliability

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D. Experimental Design

• Types of Variables
• Independent Variable
• adjusted by the experimenter
• what you vary
• Dependent Variable
• changes in response to the indep. variable
• what you measure

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D. Experimental Design

• Hypothesis
• Storing popcorn in the freezer makes it pop
  better.
• Control
• Popcorn stored at room temp.

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D. Experimental Design

• Single variable
• Storage temperature
• Constants
• Popcorn brand
• Freshness
• Storage time
• Popper

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D. Experimental Design

• Independent Variable
• Storage temperature
• Dependent Variable
• Number of unpopped kernels

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Measurement

• I. Units of Measurement
• Number vs. Quantity
• SI Base Units Prefixes
• Derived Units
• Density Calculations

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A. Number vs. Quantity

• Quantity - number unit

UNITS MATTER!!
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B. SI Units
Quantity
Base Unit
Symbol
Length
meter
m
Mass
kilogram
kg
Time
second
s
Temp
kelvin
K
Current
ampere
A
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B. SI Units
Prefix
Symbol
Factor
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C. Derived Units

• Combination of base units.
• Volume - length ? length ? length
• 1 cm3 1 mL 1 dm3 1 L
• Density - mass per unit volume (g/cm3)

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D. Density

• An object has a volume of 825 cm3 and a density
  of 13.6 g/cm3. Find its mass.

GIVEN V 825 cm3 D 13.6 g/cm3 M ?
WORK M DV M (13.6 g/cm3)(825cm3) M 11,220
g
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D. Density

• 1) A liquid has a density of 0.87 g/mL. What
  volume is occupied by 25 g of the liquid?

GIVEN D 0.87 g/mL V ? M 25 g
V 28.7 mL
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D. Density

• 2) You have a sample with a mass of 620 g a
  volume of 753 cm3. Find density.

GIVEN M 620 g V 753 cm3 D ?
D 0.82 g/cm3
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Graphing

• II. Graphing (p.48-51)
• Types of graphs
• Graphing Density

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A. Types of Graphs

• Line Graph
• shows the relationship between 2 variables

Dependent Variable
Independent Variable
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A. Types of Graphs

• Bar Graph
• shows information collected by counting

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A. Types of Graphs

• Pie Graph
• shows distribution of parts within a whole
  quantity

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B. Graphing Density
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Conversions

• III. Unit Conversions
• SI Prefix Conversions
• Dimensional Analysis

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A. SI Prefix Conversions

• 1. Find the difference between the exponents of
  the two prefixes.
• 2. Move the decimal that many places.

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A. SI Prefix Conversions
0.532
532 m _______ km
NUMBER
UNIT
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A. SI Prefix Conversions
Prefix
Symbol
Factor
move left
move right
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A. SI Prefix Conversions
0.2

• 1) 20 cm ______________ m
• 2) 0.032 A ______________ mA
• 3) 45 ?m ______________ nm
• 4) 805 dm ______________ km

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45,000
0.0805
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B. Dimensional Analysis

• The Factor-Label Method
• Units, or labels are canceled, or factored out

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B. Dimensional Analysis

• Steps
• 1. Identify starting ending units.
• 2. Line up conversion factors so units cancel.
• 3. Multiply all top numbers divide by each
  bottom number.
• 4. Check units answer.

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B. Dimensional Analysis

• Lining up conversion factors

1
1 in 2.54 cm
2.54 cm 2.54 cm
1
1 in 2.54 cm
1 in 1 in
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B. Dimensional Analysis

• Your European hairdresser wants to cut your hair
  8 cm shorter. How many inches will he be cutting
  off?

8 cm
1 in 2.54 cm
3.15 in
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B. Dimensional Analysis

• How many milliliters are in 1 quart of milk?

1 qt
1 L 1.057 qt
1000 mL 1 L
946 mL
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B. Dimensional Analysis

• 5) Assume your mass is 55 kg. How many pounds
  do you weigh?

55 kg
2.2 lb 1 kg
121 lb
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B. Dimensional Analysis

• 6) How many feet long is a 5K (5 km) race?

5 km
1 mi 1.609 km
5280 ft 1 mi
16,408 ft
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B. Dimensional Analysis

• 7) How many grams does a 10-lb. bag of potatoes
  weigh?

10 lb
1 kg 2.2. lb
1000 g 1 kg
4545 g
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B. Dimensional Analysis

• 8) Taft football needs 550 cm for a 1st down.
  How many yards is this?

550 cm
1 in 2.54 cm
1 ft 12 in
1 yd 3 ft
6.01 yd