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Chapter 1 What Is Science - PowerPoint PPT Presentation

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INTRODUCTION TO PHYSICAL SCIENCE Chapter 1 What Is Science? What is science? Quantitative description Objects and properties Quantifying properties Measurement systems Standard metric units Metric prefixes Understanding from measurement The nature of science The Scientific Method

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Chapter 1

What Is Science?

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Quantitative description

Objects and properties

Quantifying properties

Measurement systems

Standard metric units

Metric prefixes

Understanding from measurement

The nature of science

The Scientific Method

Explanations and investigations

Hypothesis and Theories

Laws and Principles


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Objects and properties

  • Objects - things that can be seen or touched

  • Properties - qualities or attributes characteristic of an object or concept

    • Fundamental Properties: Example, length of an object

    • Derived Properties: Example, speed: v = d/t

  • Referents - comparative properties using other, more familiar objects (Examples: “sky blue,” “lemon yellow”)

  • Problem - language can be subjective, ambiguous and ultimately circular!

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Quantifying properties

Measurement: uses quantitative referents - “units”

Three steps:

  • Comparing the referent unit to the property being described

  • Following a procedure specifying how the comparison is done

  • Counting how many standard units describe the property under consideration

    Essential - a number and name for the referent unit

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Measuring a book with a clip


  • Make mark at bottom of book

  • Place aligned clip above mark and make second mark

  • Continue to top

  • Record number and units: “7 clip lengths”

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English system

Many units based upon parts of the human body and other objects

Different units are not systematically related

Metric (SI) system

Established in 1791

7 base units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol) and candela (cd)

All other units derive from these

Measurement systems(based upon standardized units)

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Standard metric units for the 4 fundamental properties


  • Distance light travels in 1/299,792,458s

  • The SI unit for length is the meter.


  • Referenced to standard metal cylinder

  • The SI unit for mass is the kilogram.


  • Referred to oscillation of cesium atom

  • The SI unit for time is the second.

    Charge (See electricity lecture)

  • The SI unit for charge is the coulomb.

    All other properties (e.g. volume) derived from these. So other properties are referred to as derived properties.

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Metric prefixes

  • Simplify the conversion process

  • Help avoid writing large or small numbers.

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Understanding from measurement

  • Data

  • Ratios and generalizations

  • The density ratio

  • Symbols and equations

  • Problem solving made easy

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Measurement information used to describe

  • Objects

  • Conditions

  • Events

  • Changes

    Example: Dimensions of a cube

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Ratios and generalizations

Ratio - analysis though a quotient of 2 numbers

Example: Area/volume of a cube

Applications: crushed ice

melts faster; large potatoes

are easier to peel

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The density ratio

  • Ratio of mass and volume

  • Intrinsic property (independent of quantity)

  • Characteristic of a given material

  • “Weight density” = weight per unit volume

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Symbols and equations


  • Represent quantities, measured properties


  • Mathematical relationships between properties

  • Describe properties; define concepts; specify relationships

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More math…

  • Direct proportionality

  • Inverse proportionality

  • Proportionality constants

  • Numerical constants

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The nature of science

Beginnings of modern science ~300 years ago

  • Associated with Galileo and Newton

  • Ancient natural philosophers - “thinking only”

  • Additional component here - understanding based upon experimental and natural observational evidence – THE EMPRICAL METHOD.

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Dictionary definition of science: 1. Knowledge. 2.  Knowledge acquired by study. 3. Systematized knowledge of any one department of the study of mind or matter, as, the science of physics. Obviously, not exactly how a scientist would define science.  Science is really much more than the definition above; science involves a certain attitude about nature, science involves processes or methods, and science results in products.  David H. Ost and David George (1975) in an article "The contradictory Faces of Science" (in The Science Teacher, V. 42, No. 10, p. 14) gives the following definition of science:

" is a human activity that has evolved as an intellectual tool to facilitate describing and ordering the environment.  Once one accepts the idea that science does not exist in any other realm but the mind, it ceases to be a 'thing', an entity with its own existence.  Though scientific truth or fact is ideally objective, it is subject to human perception and logic..... As a method, science is relatively stable and universally applied, while as a body of knowledge, it is constantly changing."

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  • Attitudes of Science: Curious, objective, logical, and rational approach to the investigation of the world around us.

  • Methods of Science: Sequential approach to the investigation of natural phenomena.  For example, collecting data, evaluating data, formulating hypotheses, testing hypotheses by observation or experimentation, devising appropriate and controlled experiments, devising unbiased and objective measuring procedures, etc.

  • Products of Science:  facts, hypotheses, theories, principles, and laws of nature.

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TERMS USED IN SCIENCE(based on definitions by the National Academy of Sciences)

  • FACT: In science, an observation that has been repeatedly confirmed.

  • LAW: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances.

  • HYPOTHESIS: A testable statement about the natural world that can be used to build more complex inferences and explanations. (NOT JUST AN EDUCATED GUESS!!! THE HYPOTHESIS HAS TO HAVE THE POTENTIAL TO BE FALSIFIED!!!)

  • THEORY: In science, a well-substantiated (extensively tested and widely accepted by scientists) explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

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  • So, what is not science?  Science is based on the objective analysis of data collected from the natural world. 

  • As such, speculation based on our own biases of how we view nature is not in the realm of science.  Thus, magic, mysticism, witchcraft, astrology, and other supernatural claims are outside the confines of scientific investigation. 

  • Religious beliefs also fall outside the boundaries of science (science does not say that these beliefs are false, or true, but simply that these beliefs cannot be scientifically investigated).In other words, we cannot formulate hypotheses that are testable (have the potential to be falsified) relative to supernatural beliefs.

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The Scientific Method

  • Observe some aspect of nature

  • Propose an explanation for something observed

  • Use the explanation to make predictions

  • Test the predictions with experiments or more observations

  • Modify explanation as needed

  • Return to 3.

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  • 1. A problem or idea about nature based on observation.

  • 2. Gathering of additional initial data (information) about the idea or problem.

  • 3. Formulation of a valid hypothesis (A valid hypothesis must be testable, in other words, it must be possible to prove whether it is false or is consistent with observed facts). A hypothesis is a very tentative explanation of some observed phenomenon of nature.

  • 4. Testing of the hypothesis by observation of nature or experimentation.  In both cases, facts (data) are gathered and analyzed relative to the hypothesis.  The hypothesis is a predictive model.  The data will tell us whether the prediction(s) we have made relative to some natural phenomena is (are) consistent with the observed facts OR NOT.

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  • 5. Formulation of a theory.  If, after repeated testing and wide acceptance by the scientific community, it is determined that none of the data is inconsistent with the stated hypothesis; the hypothesis will be elevated to the status of theory.  A theory is an extensively tested and widely accepted explanation for some natural phenomenon.  On the other hand, if any of the data is inconsistent with the hypothesis, then it will be modified or rejected.

  • 6. Further testing of the theory.  In fact, theories are continually being tested as more scientific data is gathered.  Theories are also the spawning ground for additional hypotheses. 

  • Some hypotheses that are very descriptive of nature under certain sets of circumstances may eventually be elevated to the status of principles or laws of nature, but only after repeated testing and we cannot conceive of situations where the result would be different. A scientific principle is typically more specific than a scientific law, but the division is often arbitrary.  Usually scientific laws are descriptions of natural phenomena of a more general nature and of more importance than a principle.  Scientific laws and principles are descriptive and tell us how nature acts (not how nature ought to act).

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  • Some theories serve as broad scientific models of natural processes and involve many accumulated facts, and principles and laws.  A good example is the Theory of Plate Tectonics, which explains internal movements within Earth and provides an explanation as to why earthquakes and volcanoes (and other phenomena) affect certain parts of Earth's surface.  Another example is the modern Theory of Biologic Evolution, one of the strongest and most fact supported theories in science, which acts as the central unifying concept in the biological sciences (including the medical sciences).

  •   Scientific models (often representing things that we cannot observe directly) may be physical models, mental models, or equations(mathematical models).

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The Scientific Method - Example

  • Problem: What are atoms made of?

  • Hypothesis: Negative electrons orbiting positive nuclei.

  • Prediction: If atoms are collided at high speed the atoms should break apart releasing free electrons and positive nuclear particles.

  • Test (Experiment): Collide two atoms at high speed.

  • Results: Colliding two atoms yielded electrons, protons and neutrons.

  • Conclusion: (Was hypothesis verified by data? yes.) Atoms are made of electrons orbiting nuclei made of protons and neutrons.

  • Further Testing: Collide two atoms at higher energy.

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General scientific activities

  • Collecting observations

  • Developing explanations

  • Testing explanations

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Explanations and investigations

Hypothesis - a tentative explanation for some observation

Experiment - recreation of an event or occurrence to test a hypothesis (However, we can also make predictions about past events, and then make observations of nature to verify predictions. This is often done in Geology and Astronomy.)

Controlled experiment - comparing two situations with all factors alike except one

  • Control group - fixed set for comparison

  • Experimental group - differs from control group by one influencing factor

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Misleading and often absurd claims of scientific results


  • What is academic and scientific background of claimant?

  • History of review by scientific peers?

  • Participation in scientific institutions and organizations?

  • Claim published in peer-reviewed journal and independently validated by others?