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Pre-IB1 Physics

Pre-IB1 Physics. Topic One Introduction: The Physicist’s World. Concept Overview. The Nature of Physics Historical Ideas How a Physicist Works Basic Tools of the Trade Laboratory and Empirical Work Functional Relationships Data Analysis. The Nature of Physics.

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Pre-IB1 Physics

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  1. Pre-IB1 Physics Topic One Introduction: The Physicist’s World

  2. Concept Overview • The Nature of Physics • Historical Ideas • How a Physicist Works • Basic Tools of the Trade • Laboratory and Empirical Work • Functional Relationships • Data Analysis

  3. The Nature of Physics • Science = “Natural Philosophies” • Physics – deals with the nature of BASIC things: • Motion Forces • Energy Matter • Heat Sound • Light Atomic Composition

  4. The Basic Science? • Consider this: • Physics – matter • Chemistry – putting matter together • Biology – complexities of living matter • Thus, the ideas of Physics support chemistry which in turn supports biology

  5. Studying Physics • Interactions, occurrences or phenomenon which can be: • Detected • Measured • Reproduced • This has impacted the socio-economic and political structures of the world • Can you give an example of this?

  6. Think: • How has the discovery of electrical generation impacted the world? • Cf: Faraday, 1831 - a moving magnet induces an electric current • Socially • Politically • Economically • Think of 5 examples of each

  7. Historical Ideas (1)The Greek Philosopher-Scientists • Discovery of static electricity • 600 BC – Aristophanes – amber + fur • Sound as vibration of air • 550 BC – Pythagoras • “Atomos” • 400 BC – Democritus • Projectile motion and catapults • Ca. 400BC – Syracuse • Acceleration and Free-fall • 360 BC – Aristotle – started first “science school” (335BC) – Lyceum – philosophy+logic • Buoyancy and Levers • 250 BC - Archimedes

  8. Aristotle (384-322 BC) Click for the Movie!

  9. Historical Ideas (2)The Scientific Enlightenment • Scientific ideas encouraged within the boundaries of religion (church) and classical thought (Aristotle)

  10. Galileo (1564-1642) • Credits: • Astronomical telescope (1609) • Rotation of the sun through sunspots (1613) • Home imprisonment by the Inquisition (1633)

  11. Historical Ideas (3)Classical Physics • Spread of scientific ideas (The scientific method) • De-linking of science to religion

  12. Newton (1643-1727) • Credits: • Deduces inverse-square law for gravitation • “Invents” calculus (1665) • Principia Mathematica (1687)

  13. Historical Ideas (4)Modern Period • Enhancements to discoveries of the late 19th and 20th Centuries • Recognition of limitation of classical physics • Validity of Classical Physics to within certain boundaries of size (quantum physics) and speed (relativity)

  14. Credits: Special relativity (1905) General relativity (1915) Einstein (1879-1955)

  15. The Scientific Method • Credited to Galileo Galilei and Francis Bacon • Recognise a problem • Make an educated guess (hypothesis) • Predict the consequences of the hypothesis • Perform experiments to test the predictions • Formulate the simplest general rule to organise: hypothesis -> prediction -> experimental outcome

  16. Hypotheses, Theories and Laws • Hypothesis – an educated guess • Theory – a collection of a lot of information from well-tested and verified hypotheses • Law – when hypotheses are tested over and over again without being CONTRADICTED

  17. Example • Does an object twice as heavy fall twice as fast? • Aristotle’s hypothesis – 2000 years • In science, ONE verifiable contradiction outweighs reputation and authority

  18. Galileo Refutes Aristotle

  19. Testability of Hypotheses • Definition: from Greek hupothesis, proposal, supposition • A research paradigm • If a hypothesis cannot be tested, it’s speculation • Consider this statement: • “Intelligent life exists on other planets somewhere in the universe” • Is this a SCIENTIFIC hypothesis? • Why? Why not? • “Rightness and wrongness”

  20. Testability of Hypotheses They exist… They don’t exist…

  21. Physical Patterns – Logical Reasoning • Most problems can be solved through a process of logical and deductive reasoning. • These should start with a premise to lend some boundaries to the problem. • Then a logical and sequential flow of reasoning should follow: • “What caused this to happen?” • “Could this have happened without what happened before?” • “What could have happened next?”

  22. Physical Patterns – Activity Adapted: "The Secret Garden" by G. K. Chesterton from The Innocence of Father Brown Cast of characters:

  23. The Story… The mystery takes place in Valentin's home, which has a large garden enclosed by impenetrable high walls. After dinner, the guests disperse throughout the gardens. Soon a body is discovered, with its head severed, neck and shoulders slashed. The face is recognized by Valentin as that of an American thief, whose twin brother had just been guillotined. Julius Brayne has disappeared. • Dr. Simon asks: • How did the victim enter the garden? • How did Brayne leave the garden? • Why were the neck and shoulders of the victim mutilated? • WHO DID IT?

  24. Argument Analysis & Logical Induction • Premise1: The body of the victim could not (in its entirety) have entered or been brought into the garden. • Fact: The only person who was in the garden and who is unaccounted for is Brayne. • L/Induction (1,2): The body is (at least in part) that of Brayne. • Premise2: The head is not that of Brayne, nor of anyone else who was in the garden. • L/Induction (3,4): The head and the body do not belong to the same person. • L/Induction (4): The head was brought into the garden. • Premise3: The only person who could have brought a head into the garden is Valentin. • L/Induction (6,7): Valentin brought the head into the garden. • Premise4: Whoever brought the head into the garden is the murderer. •  L/Induction (8,9): Valentin is the murderer.

  25. Basic Tools – Quantities and Units Q: How many things in the box?

  26. Basic Tools – Quantities and Units How thick is the stack of $$$?

  27. Quantities and Units • All physical quantities consist of a numerical magnitude and a unit • There are some SI base quantities you should know: • Length • Mass • Time • Electric current • Thermodynamic temperature • Luminous intensity • Amount of substance • What are their SI units?

  28. SI Prefixes and Standard Form • For very large or very small numbers. • You should be familiar with: •  • m • c • d • k • M • Their standard forms?

  29. Scalar and Vector Quantities • Some quantities have a directional component to them • Example: • Ali walked 5 m • Jon walked 5 m due North • Scalar – quantity with a magnitude only (DISTANCE) • Vector – quantity with both a magnitude and a direction (DISPLACEMENT)

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