Chapter 1The Scientific Method

The Physical UniverseK. B. Krauskopf

A. Beiser

Show Explained• The notes on the following slides will give you an idea

of the sort of things your tutor may point out to you in an effort to assist you in learning the material

1.1 What is Science?

• Science is a Process

• asking and answering questions

• Science is not a collection of facts

1.1 Two Kinds of Science

Life Science

• living things

Physical Science

non-living things

1.1 The Scientific Method

Four Steps.1 Formulating a problem.2 Observation and experiment.3 Interpretation

hypothesis.4 Testing the interpretation

1.1 Hypothesis and Theory

• Hypothesis: an educated guess - that can be tested

• Theory: the synthesis of a LARGE body of information encompassing well-tested and verified hypotheses from experimental observations

1.1 Observation and Experiment

Observation can be done without an actual experimentAn experiment is a careful observation that may require recording quantitative information about the observed phenomenon.• An Experiment is simply manipulating nature and

then observing the result

1.1 Laws of Nature

• Represents our current best understanding• Subject to change based upon additional

observationsApply everywhere in the universe

• From atoms to galaxies• Can be used to predict unknown phenomena• Allows us to understand what occurs in places we

cannot examine directly

1.1 Theories and Models

• A Law tells us what• A Theory tells us why

A Theory is more than a hypothesis:Fully developed logical structureBased on well understood general principles

• A Model is a simplified version of realitye.g. the Earth is a sphere

1.2 Why Science is Successful

Scientific knowledge is not frozen, we constantly add to itScientists question previous resultsCommon sense is not a valid argument

1.2 Science and Religion

Science has been at odds with religious doctrineGalileo was forced under the threat of torture to deny that the earth moves about the sunCreationism vs. evolutionary theory

1.11 Neptune cont’d

Calculations based on the law of gravity predicted the position of an unknown body.The prediction was tested, resulting in the discovery of Neptune.

1.2 Science and Religion

• Science: observe, record and discover natural phenomena based on experimental evidence acquired by using a rigid scientific method; skepticism is key

• Religion: a means of understanding the source, purpose and meaning of our world based on faith; Many principles are accepted without question

1.12 Units

A physical measurement consist of a number and a unit or standard quantity. Standard quantities such as the mile are known as units.

1.12 Units cont’d

The result of every measurement has two parts:

1. the number2. the unitsFor example: 100 miles, 10 meters, etcThe most widely units today are the International Units or SI units.

1.12 Base Units

SI unit

Quantity Name Symbol

Time second sLength meter mMass kilogram kgAmount of substance mole molThermodynamic temperature Kelvin KElectric current ampere ALuminous intensity candela cd

1298347.23487561

’s p

lace

10

’s p

lace

10

0’s

pla

ce1

000

’s p

lace

10

th’s

pla

ce1

00

th’s

pla

ce

Multiply by 10 or divide by 10 for each place!

1.12 Why Metric?

1.12 Subdivisions and Multiples of Base Units

Prefix Power of 10 Abbreviation Prefix Power of 10 Abbreviation

Hecto- 102 h Centi- 10-2 c

Kilo- 103 k Milli- 10-3 m

Mega- 106 M Micro- 10-6 µ

Giga- 109 G Nano- 10-9 n

Tera- 1012 T Pico- 10-12 p

1.12 Units: Examples1km = 1 kilometer = 103 meters

= 1000 meters

1 GHz = 1 GigaHertz = 109 Hertz = 1000,000,000 Hertz

1mm = 1 millimeter = 10-3 meters= 0.001 meters

1nsec = 1 nanosec = 10-9 seconds= 0.000,000,001 seconds

1.12 kilometers, meters and centimeters

1.12 Conversion Factors1 meter (m) = 100 cm = 1000 mm = 3.28 ft

1 kilometer (km) = 1,000 m = 0.621 mile

1 mile (mi) = 5280 ft = 1.609 km

1 foot (ft) = 12 in = 0.305 m = 30.5 cm

1 day = 24 hrs = 86,400 s

Distance: Example 1.1

How long is 878 m in terms of

a. kilometers

b. miles

Distance: Example 1.1.a

Distance: Example 1.1.b

1.12 Significant Figures

We can only trust as many output digits as the input variable with the fewest digits:

If we have a product of a three and a four digit number our result can only have three significant figures

It is okay to use more digits in the intermediate steps and then to round the final result