Slide 1IntroductionWhy Study Physics?Scientific ClassificationSlide 5Lord KelvinLord Kelvin QuotesThe Ones Lord Kelvin Got WrongScientific MethodSlide 10New Hypothesis?The New HypothesisSlide 13Physics DefinitionsScientific NotationSlide 16UnitsSlide 18Slide 19Slide 20Slide 21Problem Solving TechniquesSlide 23TrigonometryDimensional AnalysisSlide 26Slide 27Slide 28Slide 29ApproximationsGraphsSlide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 1Chapter 1IntroductionMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 2•Why Study Physics?•Mathematics: The Language of Physics•Physics Definitions•Scientific Notation and Significant Figures•Units•Dimensional Analysis•Problem Solving Techniques•GraphsIntroductionMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 3Why Study Physics?Physics is the foundation of every science (astronomy, biology, chemistry…).Many pieces of technology and/or medical equipment and procedures are developed with the help of physicists. Studying physics will help you develop good thinking skills, problem solving skills, and give you the background needed to differentiate between science and pseudoscience.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 4Scientific ClassificationIf its dead it’s BiologyIf it stinks it’s ChemistryIf it doesn’t work it’s PhysicsMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 5"When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarely, in your thoughts advanced to the stage of science.”Lord KelvinMathematics - The Language of PhysicsMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 6Lord KelvinItems Named for KelvinJoule–Thomson effectThomson effect (thermoelectric)Mirror galvanometerSiphon recorderKelvin materialKelvin water dropperKelvin waveKelvin–Helmholtz instabilityKelvin–Helmholtz mechanismKelvin–Helmholtz luminosityKelvin transformKelvin's circulation theoremKelvin bridgeKelvin sensingKelvin equationMagnetoresistanceFour-terminal sensingCoining the term 'kinetic energy'William Thomson, 1st Baron Kelvin (or Lord Kelvin), (26 June 1824 – 17 December 1907) An Irish-born British mathematical physicist and engineer.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 7Lord Kelvin Quotes“In science there is only physics; all the rest is stamp collecting.”“In physics, you don't have to go around making trouble for yourself - nature does it for you.”MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 8The Ones Lord Kelvin Got Wrong•“Heavier-than-air flying machines are impossible.”•"There is nothing new to be discovered in physics now, All that remains is more and more precise measurement.”•"X-rays will prove to be a hoax.”•"Radio has no future.”•Writing to Niagara Falls Power Company: "Trust you will avoid the gigantic mistake of alternating current.”•[The vector] "has never been of the slightest use to any creature."MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 9Scientific Method-Explain what we perceive in nature.-Only include the largest effects at first.-At what level do we want to explain the phenomenao What do we include?O What do we leave out?-Find the most appropriate mathematical frameworkMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 10Scientific Method-Test our theory on the known phenomena that we wanted to explain – by design it should find agreement here.-Predict, based on your equation, what will happen in another situation.-Compare prediction with experimental results.-Repeat the prediction and experiment scenario and keep track of results that agree with your “theory” and results that disagree.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 11New Hypothesis?Since we ignored some of the smaller phenomena in creating our theory we should expect some disagreement when our experimental conditions take us into a region of experimental space where those ignored phenomena might be important.In the beginning we might try to make small corrections to the theory so that we can remove some of the smaller areas of disagreement.If the list of disagreements gets too long or one or more experiments produce large disagreements then our theory is in trouble.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 12The New HypothesisAn improved theory is needed. However, our earlier theory did explain some phenomena so any new theory will be required to reproduce those older results in the region where our theory was correct.In other words our earlier theory will need to be a limiting case of any new theory that is proposed.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 13The New HypothesisDirection for a new theory-Simple is better, few adjustable parameters-Equations have an element of beauty o The most beautiful equation is the right one o However, beauty can be in the eye of the beholder.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 14Physics DefinitionsBe aware that physicists have their own precise definitions of some words that are different from their common English language definitions.Examples: Speed and velocity are no longer synonyms; Acceleration is a change of speed or direction.A general solution to an equation applies ALL the time and not MOST of the time.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 15Scientific NotationThis is a shorthand way of writing very large and/or very small numbers. .0000456 ==> 4.56 x 10-5 or 4.56E-05 1,236,000 ==> 1.236 x 10+6 or 1.236E+06MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 161. Nonzero digits are always significant.2. Final ending zeroes written to the right of the decimal are significant. (Example: 7.00.)3. Zeroes that are placeholders are not significant. (Example: 700,000 versus 700,000.0.)4. Zeroes written between digits are significant. (Example: 105,000; 150,000.) Significant FiguresMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 17UnitsSome of the standard SI unit prefixes and their respective powers of 10.10-9nano (n)103kilo (k)10-6micro ()106mega (M)10-3milli (m)109giga (G)10-2centi (c)1012tera (T)Power of 10PrefixPower of 10PrefixMFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 18The quantities in this column are based on an agreed upon standard.MFMcGraw - PHY 1401Ch_01a-Revised 5/28/2010 19Some Useful