Schab Lecture 1(2)

7/30/2019 Schab Lecture 1(2)

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Conceptual Physics

PHY 103

Professor Schab

Lecture1:

About Science


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What is Science?

Science is a logical and rigorous method

used to investigate the

world around us.

Science has specific rules that guide

this investigation.

Science gives specific meanings to some common words:

theory, force, speed, etc.


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Scientific Measurements

Measurements

relate to how much you know

about something.

of pinhole images of the Sun

nicely lead to a calculation

of the Suns diameter.


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Measurements can be defined in

many ways.

In the US, we use the English(Imperial) System: units such as

miles, pounds, gallons, etc.

In the rest of the world, the metr ic systemis used.

When doing science, everyone has to agree on a system.

Measurements


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Scientific Notation

In science, we use numbers that are very small and very large.

16x1074.600000006740000000

-11x104.3340000000000.

Writing out numbers such as 67400000000000000 or

.000000000034 is cumbersome and hard to read.

So scientists use Scienti f ic Notation.


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Common Metric Prefixes

310001.01000

1milli 21001.0100

1centi

3101000kilo 6101000000mega

9101000000000giga

24100000000000000001000000000yotta

And the not so common...


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Multiple Prefix Symbol Common Name

(10100)100 anton A antonplex

(1010)100 - - googolplex

10100 - - googol

1024

yotta Y heptillion

1021 zetta Z hexillion

1018 exa E quintillion

1015 peta P quadrillion

1012 tera T trillion

109 giga G billion

106 mega M million

103 kilo k thousand

102 hecto h hundred

101 deca da ten

10-1 deci d tenth

10-2 centi c hundreth

10-3 milli m thousandth

10-6 micro (Greek mu) millionth

10-9 nano n billionth

10-12 pico p trillionth

10-15 femto f quadrillionth

10-18 atto a quintillionth

10-21 zepto z hexillionth

10-24 yocto y heptillionth

Decimal

Prefixes and

Multiples,

Powers of Ten


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Science uses the International System of Units: SI. This system

defines certain basic properties that every other measurement

depends upon. It is basically the metric system.

The basic units chosen must be easy toduplicate anywhere in the world.

Units

Units are every bit as important as the numbers.


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Consistency

It is VERY important to keep unitsconsistent.

If you mix up systems, for

example, using miles with kilograms,you will get wrong answers!

When doing calculations, the units are

every bit as important as the numbers.

Ask NASA! They lost a 250 million dollar Mars spacecraft

because of mixed up units!


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Time

Time is a fundamental property of

the universe.

Time is subjective for humans.Science requires a common,

unchanging value.

The second is the duration of 9,192,631,770 periods of the radiation

corresponding to the transition between the two hyperfine levels of

the ground state of the cesium-133 atom.


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Length

Length in the MKS system is defined as the meter.

The meter is the length of the path traveled by light in vacuum during

a time interval of 1/299 792 458 of a second.


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Mass

Mass measures the amount of matter an object contains. It is NOTthe same thing as weight!

Mass is measured in kilograms.

The kilogram is defined by the mass of the international prototype of

the kilogram stored in Paris.


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The Scientific Attitude

The scientific attitude is one of

inquiry.

experimentation.

willingness to admit error.


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The Scientific Attitude

Scientists

are experts at changing their minds.

must accept experimental findings

test for erroneous beliefs

understand objections and positionsof antagonists.


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Hypothesis

Hypothesis: An educated guess; a

reasonable explanation of an observation

or experimental result that is not fully

accepted as factual until tested over andover again by experiments.

A hypothesis is an educated guess about

how things work: "If _____[I do this]_____, then _____[this]_____ will

happen."


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Fact

Fact: a statement about the world that competent

observers who have made a series of observations

agree on.

A fact is not immutable and absolute, but is generally a

close agreement by competent observers of a series of

observations of the same phenomena. The observations

must be testable.

Since the activity of science is the determination of the

most probable, there are no absolutes.

Facts that were held to be absolute in the past are seen

altogether differently in the light of present-day

knowledge.


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Scientific Law

Law (principle: a general hypothesis or

statement about the relationship of natural

quantities that has been tested over and

over again and has not been contradicted.

A scientific law can often be reduced to a

mathematical statement, such as F=ma;

it's a specific statement based on empiricaldata, and its truth is generally confined to

a certain set of conditions.


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Scientific Theory

Scientific theory is a synthesis of a large body

of information that encompasses well-tested and

verified hypotheses about certain aspects of the

natural world. It's generally -- though by no means always -- a

grander, testable statement about how nature

operates.

You can't necessarily reduce a scientific theory

to a pithy statement or equation, but it does

represent something fundamental about how

nature works.


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Scientific Theory

The theory can be refined, or with new

information it can take on a new direction.

It is important to acknowledge the

common misunderstanding of what a

scientific theory is, as revealed by those

who say, But it is not a fact; it is only a

theory.

Many people have the mistaken notion

that a theory is tentative or speculative,

while a fact is absolute.


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The Scientific Method is a logical and rational

order of steps by which scientists come to

conclusions about the world around them. The Scientific Method helps to organize

thoughts and procedures so that scientists can

be confident in the answers they find. Scientistsuse observations, hypotheses, and deductions to

make these conclusions.

What is the Scientific Method?


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The steps of the Scientific Method are:

Observation/Research

Hypothesis Prediction

Experimentation

Conclusion



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1. The observation is done first so that you knowhow you want to go about your research.

2. The hypothesis is the answer you think you'll

find.

3. The prediction is your specific belief about thescientific idea: If my hypothesis is true, then I

predict we will discover.....

4. The experiment is the tool that you invent to

answer the question.

5. The conclusion is the answer that the experiment

gives.



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Science, Art, and Religion

Comparison of science, art, and religion by

domain:

Science is of the natural order and involves

the discovery and recording of natural

phenomena.

Art is the interpretation and expression of

human experience. Religion involves faith and worship of a

supreme being.


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Science and Technology

Science is concerned with gathering and

organizing knowledge.

Technologyis the use of scientific

knowledge for practical purposes and to

provide tools for further exploration.


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Errors in Experiments

Error in experiments have several sources.

First, there is error intrinsic to instruments of

measurement.

Second, there is non-random or systematicerror, due to factors which bias the result in one

direction.

No measurement, and therefore no experiment,can be perfectly precise.


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Random Error

There is error intrinsic to instruments of

measurement.

Because this type of error has equal

probability of producing a measurement

higher or lower numerically than the "true"

value, it is called random error.

Random errors can be reduced by

averaging a large number of

measurements.


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Systematic Error

There is non-random or systematic error, due tofactors which bias the result in one direction.

A reproducible discrepancy between the result

and "true" value that is consistently in the same

direction

Systematic error is sometimes called "bias" and

can be reduced by applying a "correction" or

"correction factor" to compensate for an effectrecognized when calibrating against a standard.

Unlike random errors, systematic errors cannot

be reduced by increasing the number of

observations.


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Accuracy versus Precision

Accuracy is how close a measured value

is to the actual (true) value.

Precision is how close the measured

values are to each other.


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Review Questions

S f


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a. guide to improving human behavior.

b. recipe for avoiding conflicts.

c. process for finding connections in nature.

d. handbook for establishing truth.

Science is an organized body of

knowledge about nature and also a


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The size of the Moons shadow on

Earth is

a. smaller than the size of the Moon.

b. about the same size as the Moon.

c. larger than the size of the Moon.

d. incapable of being observed.

Th i f b th th M d th


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a. both have the same diameters.

b. both are at about the same distance from

Earth.c. the smaller Moon is closer to Earth than the

Sun.

d. both the Moon and the Sun circle Earth.

The sizes of both the Moon and the

Sun are the same in the sky, which

indicates that

Th i f th i f th S


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The size of the images of the Sun

on a sidewalk beneath a sunlit tree

depends ona. the size of the openings between leaves

above.

b. whether or not the openings between leavesare circular.

c. the distance between the sidewalk and the

openings between leaves above.

d. how close the location is to the equator.

A h th t l


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A person who says, thats only a

theory likely doesnt know that a

scientific theory is aa. guess that involves many facts.

b. hypothesis of sorts.

c. vast synthesis of well-tested hypotheses andfacts.

d. guess that may or may not be factual.

M i t t th t t f


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More important than a test for

proving a hypothesis right is a test for

a. knowing full well that it is right.

b. proving more than one way that it is right.

c. proving it wrong.d. elevating it to a scientific theory.

Whi h f th i i tifi


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Which of these is a scientific

hypothesis (that could be proved

wrong)?a. Atoms in proper proportions make us feel good.

b. Atoms are in all the stars in the universe.

c. An atom is the smallest bit of matter in amaterial.

d. Distant galaxies have atoms not found on Earth.

A strength of science is that


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A strength of science is that

scientific theories

a. are fixed.

b. can change with new data.

c. are the hypotheses of brilliant people.d. are verifiable.

A fact in science is something that


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A fact in science is something that

a. is forever true.

b. may change over time.

c. cannot be denied.d. agrees with ancient records.

Science is concerned mainly


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Science is concerned mainly

with the

a. natural world.

b. spiritual world.

c. difference between right and wrong.d. search for eternal truths.

Schab Lecture 1(2)

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