Chapter 1 Physics, the Fundamental Science.ppt

1、Chapter 1 Physics, the Fundamental Science,The Scientific Enterprise Developing Scientific Explanations (Rainbow) Look it up “Appeal to Authority” Scientists do this all of the time Depends on someone elses workInvent your own explanation: Educated Guess Use your common sense Use what you know about

2、 other phenomenaDo some tests to see if your idea is rightChange your ideas or decide that they seem correctTalk about what you saw or did with others,B. The Scientific Method Careful observation of natural phenomena Formulation of testable rules based on experience Develop hypothesis to explain the

3、 observed rules Test the hypothesis by experiment Communicate with others C. Definitions Emperical Law: generalization derived from observation Hypothesis: educated guess at the explanation of a problem Theory: testable organized knowledge explaining a part of natureUsing Scientific Method on an Eve

4、ryday Phenomena Observe: dont do well on first several assignments in a class Hypotheses Experiment Communicate,Scope of Physics,II. Where does Physics fit in Science?Physical Sciences: physics, chemistry, geology, astronomy, meteorology Physics: study of the basic nature of matter and the interacti

5、ons that govern its behavior Chemistry: study of composition, structure, and reactions of the various forms of matterLife Sciences: Biology: study of living organisms and life processes Health Sciences: study of determining and maintaining wellnessSize of Matter studied Physics: smaller than atoms,

6、bigger than molecules Chemistry: atoms and molecules Biology: collections of living molecules,D. Subfields of PhysicsClassical Physics: well developed before 1900 Mechanics: forces and motion (ball in flight) Thermodynamics: temperature, heat, and energy (melting of ice) Optics: light (lenses) Elect

7、ricity and Magnetism: forces and current (circuits)Modern Physics: greatest development after 1900 Atomic Physics: structure/behavior of atoms Nuclear Physics: atomic nuclei Particle Physics: subatomic particles Condensed Matter Physics: solids/liquidsApplied Physics: using physics to solve everyday

8、 problems Also known as Engineering,Related to Chemistry,III. Math and PhysicsWhy is there so much math in physics? Math is a compact way to express physics ideas But, most physics ideas can be discussed with words too! This class will use Algebra and basic math but the ideas are most importantMeasu

9、rements Physicists use measurements (experiments) to test their hypotheses Units: physical quantities are meaningless without unitsProportions Example: A recipe for 3 people uses 1 cup of millk. How much milk is needed for 4 people? -Words: the quantity for 4 is the same ratio as the ratio of 4 peop

10、le to 3 people-Math: -Units: answer is meaningless without them (4/3 milk?, 4/3 people?),Dimensional Analysis Also known as canceling units (Doing Algebra on units) This is the key step to solving many of the problems in the course Example: How many seconds are in one year?Scientific Notation: Appen

11、dix B Present very large and very small numbers compactly 3,153,600,000 = 3.1536 x 109 0.000000025 = 2.5 x 10-8 Addition and Subtraction Write compacted numbers out or use a calculator Example: 5.36 x 104 + 4.02 x 10-3 = ?Multiplication and Division Multiplication: multiply the numbers and add up th

12、e exponentsDivision: divide the numbers and subtract the exponents,53,600 + 0.0040253,600.00402,(3 x 106) x (2 x 10-4) = 6 x 102,(9 x 106) x (3 x 10-4) = 3 x 1010,F. Metric SystemG. Using the Book It tries to relate physics concepts to everyday life Problems: Word questions (Q), Exercises (E), Challenge (CP) Answers to odd E, CP in back of book; get help if you need it Use the Summary at the end of chapters,