ch. 1 - the nature of science defining science problem-solving scientific method experimental...

Ch. 1 - The Nature of Science

Defining Science

Problem-Solving

Scientific Method

Experimental Design

Section 1: The Methods of Science

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

A. Defining Science

PURE

human genetics

polymer science

atomic theory

study of the human ear

APPLIED

DNA fingerprinting

Lycra® spandex

nuclear weapons

hearing aids

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

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.

B. Problem-Solving

3. Execute your plan.

4. Evaluate your results. Did you solve the problem? Is your answer reasonable?

Identify - Plan - Execute - Evaluate

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

C. Scientific Method

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

They are revised when new information is discovered.

THEY ARE NOT SET IN STONE!

C. Scientific Method

1. Determine the problem.

2. Make a hypothesis.

3. Test your hypothesis.

4. Analyze the results.

5. Draw conclusions.

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.

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?

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

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

D. Experimental Design

Hypothesis:

Storing popcorn in the freezer makes it pop better.

Control:

Popcorn stored at room temp.

D. Experimental Design

Single variable:

Storage temperature

Constants:

Popcorn brand

Freshness

Storage time

Popper

D. Experimental Design

Independent Variable:

Storage temperature

Dependent Variable:

Number of unpopped kernels

Section 2: Standards of Section 2: Standards of MeasurementMeasurement

Units and StandardsUnits and Standards

Standard:Standard: an exact quantity that is used for an exact quantity that is used for comparisoncomparison International Bureau of Weights and MeasuresInternational Bureau of Weights and Measures

Measurement SystemsMeasurement Systems EnglishEnglish

Pounds, ounces, gallons, etc.Pounds, ounces, gallons, etc.

MetricMetric ( (SISI, , from the Frenchfrom the French, Le Systeme Internationale , Le Systeme Internationale d’Unites)d’Unites) Meters, kilograms, KelvinsMeters, kilograms, Kelvins

– Preferred for science because it’s based on multiples Preferred for science because it’s based on multiples of tenof ten

– Accepted and understood throughout the worldAccepted and understood throughout the world

Metric Base UnitsMetric Base UnitsQUANTITY BASE

UNIT SYMBOL EXAMPLE

length 1 meter m 1 baseball bat = 1 meter

mass 1 kilogram kg 1 person = 65 kilograms

time 1 second s you read this in 1 second

electric current 1 ampere A hairdryers use 8 amps of current

temperature 1 Kelvin K Water boils at 373K

amount 1 mole mol 18 g of H2O = 1 mole of water

candela 1 candela cd Fog lights can be 1000 cd

METRIC PREFIXES

Prefix Symbol Decimal Sample Expression

Mega M 1 000 000 1 Mm = 1 000 000 m

Kilo k 1 000 1 kg = 1000 g

Hecto h 100 1 hm = 100 m

Deca da 10 1 das = 10 s

*BASE UNIT* m, s, K, mol, g **1 base unit ** *************

Deci d 0.1 1 dmol = 0.1 mol

Centi c 0.01 1 cm = 0.01 m

Milli m 0.001 1 mg = 0.001 g

Micro μ 0.000 001 1 μK = 0.000 001 K

One Step Metric ConversionsOne Step Metric Conversions Convert between a prefix and a base Convert between a prefix and a base

unitunit Conversion factors relate prefixes and Conversion factors relate prefixes and

base units base units

Example: How many centimeters are Example: How many centimeters are equal to 2.5 meters?equal to 2.5 meters?

Plan: Use conversion (1 cm = 0.01m)Plan: Use conversion (1 cm = 0.01m) Math: Math:

givenunits

wantedunits

1. Multiply by what’s on the top

2. Divide by what’s on the bottom

3. Diagonal units cancel

1 conversion means 1 “fence

post!”

2.5 m 1 cm = 250 cm 0.01 m

Sample problems:Sample problems: How many kilometers are equal to 750 000 How many kilometers are equal to 750 000

meters? meters? (1 km = 1000 m)(1 km = 1000 m)

How many seconds are equal to 350 000 000 How many seconds are equal to 350 000 000 microseconds? (1 microseconds? (1 µs = 0.000 001 s)µs = 0.000 001 s)

How many millimoles are equal to 15 moles? How many millimoles are equal to 15 moles? (1 mmol = 0.001 mol)(1 mmol = 0.001 mol)

How many Kelvin are equal to 300 decaKelvin? How many Kelvin are equal to 300 decaKelvin? (1 daK = 10 K)(1 daK = 10 K)

Two Step Metric ConversionsTwo Step Metric Conversions Convert between 2 prefixesConvert between 2 prefixes Conversion factors relate prefixes and Conversion factors relate prefixes and

base units base units

Example: How many centimeters are Example: How many centimeters are equal to 2.5 kilometers?equal to 2.5 kilometers?

Plan: Use conversions Plan: Use conversions (1 cm = 0.01m) and (1 km = (1 cm = 0.01m) and (1 km = 1000 m)1000 m)

Math: Math:

givenunits

wantedunits

1. Multiply by everything on top2. Divide by everything on bottom3. Diagonal units cancel

2 conversions means 2 “fence posts!”

2.5 km 1000 m 1 cm = 250 000 cm 1 km 0.01 m

Sample problems:Sample problems: How many kilometers are equal to 750 000 How many kilometers are equal to 750 000

decimeters? decimeters? (1 dm = 0.1 m) and (1 km = 1000 m) (1 dm = 0.1 m) and (1 km = 1000 m)

How many Megaseconds are equal to 350 000 000 How many Megaseconds are equal to 350 000 000 microseconds? microseconds? (1 (1 µs = 0.000 001 s) µs = 0.000 001 s) and (1 Ms = 1 000 000 s) and (1 Ms = 1 000 000 s)

How many millimoles are equal to 1.5 kilomoles?How many millimoles are equal to 1.5 kilomoles?(1 kmol = 1000 mol) and (1 mmol = 0.001 mol)(1 kmol = 1000 mol) and (1 mmol = 0.001 mol)

How many centiKelvin are equal to 300 decaKelvin? How many centiKelvin are equal to 300 decaKelvin? (1 daK = 10 K) and (1 cK = 0.01 K)(1 daK = 10 K) and (1 cK = 0.01 K)

Derived UnitsDerived Units Derived units are not measured directlyDerived units are not measured directly

They are the result of a calculation involving They are the result of a calculation involving several measurementsseveral measurements VolumeVolume DensityDensity

Units are combinations of the units used in making Units are combinations of the units used in making the measurementsthe measurements Volume of a regularly-shaped object: mVolume of a regularly-shaped object: m33, cm, cm33

Volume of liquid: mL, LVolume of liquid: mL, L Density of a solid:Density of a solid:

Density of a liquid: Density of a liquid: 3cm

g

mL

g

Volume DeterminationVolume Determination Volume:Volume: The amount of space an object occupies The amount of space an object occupies

OROR the amount of space available inside of an the amount of space available inside of an objectobject

Regularly shaped object:Regularly shaped object:

V = L x W x H = __cmV = L x W x H = __cm33 or __m or __m33

Irregularly shaped object: Water Irregularly shaped object: Water DisplacementDisplacement Place object in a known volume of waterPlace object in a known volume of water Determine the difference in water levels after Determine the difference in water levels after

object is in the waterobject is in the water Convert to appropriate units (Convert to appropriate units (1 mL = 1 cm1 mL = 1 cm33))

Density DeterminationDensity Determination

Density:Density: the expression for the amount of the expression for the amount of matter contained in a certain volumematter contained in a certain volume

Formula:Formula:

Volume

massDensity

3cm

gmL

g m

D V

Section 3: Communicating with Graphs

A. Types of Graphs

Line Graph

shows the relationship between 2 variablesD

epen

den

t V

aria

ble

Independent Variable

A. Types of Graphs

Bar Graph

shows information collected by counting

A. Types of Graphs

Pie Graph

shows distribution of parts within a whole quantity

B. Graphing & DensityM

ass

(g)

Volume (cm3)

Δx

Δyslope D

V

M