PSC 1121 Intro to Physical Science

1. PSC 1121Intro to Physical Science Dr. Jeff Bodart D008 Natural Science bodartj@chipola.edu 526-2761 EXT.3252 PSC 1121 Instructor Course Handout Course Content: Read textbook additional material included in lecture additional material on web site - not covered well in textbook - practice problems Course grade: Homework and Class Activities 20% Chapter Exams (5 plus final) 80% One HW grade dropped No exam grades dropped Exams: multiple choice and problem-solving concept and numerical problems

2. F A W E • - understand world around us • Relate physical quantities to the environment • predict from observations • recognize false reasoning (magic- pseudoscience) • Appreciate technological workings Science Historical Background: NATURAL MOTION Ancient Greeks - four elements Natural State: rest rocks fall-fire rises medium Adds resistance to motion - speed

3. UNNATURAL MOTION spears, arrows, projectiles medium vacuum ASTRONOMY Geocentric Universe - Earth Centered 5th element - aether

4. World Understood sun, moon, stars rises in east - sets in west heavy objects fall faster thrown rock hits ground and stops • Not science, but made predictions • Described specific cases • Why without knowing how • Qualitative measure - fast, slow Galileo - Father of Scientific Method quantitative measurements on inclined plane - measure time - measure position } motion d All objects fall same Natural state constant speed-uniform motion More complexity in measurements - telescope -Moon rough -Jupiter has moons -Mars orbit not circular (Tycho Brahe) Heliocentric (Sun-centered)

5. EXPERIMENTATION TO SEE HOW WORLD WORKS describe and predict quantitatively make observation preliminary explanation predict from explanation test prediction modify explanation Scientific Method LED TO SCIENTISTS - look at various problems describe how-understand why Basic (Fundamental) Science- describe and understand self-testing: test by application peer review - repeatable objective - not ugly or beautiful Science only as good as the observations Applied Science ability to predict and exploit nature electric, gas power building construction

6. Tools of Science - made to understand nature Scientific Law - statement based on what is always observed use to predict unknown outcome from starting point often mathematical- dependent and independent variables “what goes up comes down” usually Scientific Theory - working explanation of why a law is true not proven, accepted if passes all tests constant fine-tuning “gravity acts between two objects with mass” Scientific model - makes a theory easy to understand or use simple picture of the theory that accounts for all aspects of the theory F=G M1*M2/R2 M1 M2 R Attractive force acts between centers of spheres

7. Technology Applying scientific work to real world situations APPLIED SCIENCE Consequences on physical world Transportation: horsespace shuttle environmental effects Technology assessment -understand consequences in advance - before too late DDT, Pollution, OZONE Problem Technology developed by: single researchers (basement science) penicilin, nuclear fission, liquefaction of H and He BIG science - large collaborations university, government, industry multidisciplinary-phys, chem, bio, eng many fields to address all aspects brute force - SHUTTLE, ENERGY Multinational - modern communications journals, WWW, email, FAX access to results of others, peer review Larger collaborationsLarger grantsLarger science

8. Taken from Chapter 1 “What is Science?” and Appendix A “Mathematical Review” Physical Science and Measurement Physical Quantities - measure to quantify physical properties (qualities or attributes of object) symbol representations: d, v, F, p Physical Science -measure physical quantities -relate to environment -predict position, speed, force energy, voltage, chemical properties description has both: number - how much of a quantity units - well-defined reference amount measurement - comparing a property of an object to a well-defined referent referent - describes a specific amount of a property - PHYSICAL STANDARD STANDARDIZE - measure the same as everyone else History : cubit, foot, hand, inch, palm (anatomy) change over time new king, wear, disaster NEED CONSISTENT SYSTEM OF UNITS

9. ENGLISH CUSTOMARY SYSTEM OF UNITS MOST COMMON SYSTEM IN USA - -foot, pound, second -changes in parts of world -now in terms of metric -not common in rest of world need a world-wide system for science, trade industry Metric System ( 1791 ) -based on easily reproduced standards -quantities measured as number and unit - meter, gram, second standard units -a well-defined amount of a physical quantity 1. A quantity that doesn’t change over time 2. Scheme to measure consistently length - size of earth - length of Pt-Ir bar - speed of light (1/300000000 sec) time - mean solar day (24 hours,60 min, 60 s) - Cs atomic clock mass - mass of a 1 liter of water Temperature sound color light intensity electric current 10 million meters

10. Conferences to discuss proper units International bureau of Weights and Measures meet every 4 years to refine standards U.S. National Bureau of Standards Primary standard - reproduction of standard unit - locked away Secondary standard - copy of primary to reproduce commercial copy US is committed to changing to metric -voluntary program -compete internationally commerce, sports, science -mixtures of units for transition (confusing) cars, soda, Olympics, road signs -must know how to convert between units 1 inch = 2.54 cm conversion relation SI System of Units (Systemme Internationale) M K S units standardized units used in Physical Sciences base units - describe fundamental properties length (m), mass (kg), time (s), temperature (K), Current (ampere), light intensity (candela), number (mole).

11. Measuring physical quantities: relate symbolic quantities (number & unit) to the circumstances of an object (gravity, external,etc.) How to deal with numbers (how much)? Exponential (Scientific) Notation: shorthand way of dealing with very large or small numbers 7.2x106 Coefficient 1-9.99999 can work with regular numbers(coefficient) separate from powers of 10 9.76x105 = 9 7 6 0 0 0 . How does it work.... Examples: = x10 4.75x105= 0.00542 = x10 4.03x10-4= 342.04 = x10 289.0 = x10 exponent-how many decimal places to move } exponential-shows power of ten scale Positive exponent >1 Negative exponent <1

12. Multiplying and Dividing exponentials Treat two parts separately: (5.4x105)(2.34x103) =(5.4 x 2.34)(105x 103)) =12.636 x (10 5+3) =(1.2636 x 101) x 108 Dividing: divide coefficients separate from exponential 4.28x104 3.5x102 = 1.223 x 104-2 = 1.223x102 Example: (3.6x107) / (6.4x10-3) = (4.3x10-12) / (7.2x105) = Or just use calculator: exponential button EXP or EE -stands for “times ten to the” Type in the coefficient, press [EXP or EE] and then the exponent times/divided coefficient, [EXP or EE] and exponent you can try the examples above using your calculator add exponents when multiplying 10’s 4.28 104 3.5 102 = x Subtract exponents

13. Multiples and Submultiples - metric prefixes Different scales of measurement: length Atoms 10-9 Cells 10-6 Bugs 10-3 People 100 City size 103 To moon 106 To sun 109 -shorthand indicates scale -don’t have to carry zeros -agreed upon world wide -use conversion relation above: 4.2 Mm = 4.2 x (106 m)=4.2x106 m Dimensional Analysis - manipulating/converting units 36 inches feet? conversion relation relates equality of units 1 foot = 12 inches 36 inches x = Example: A pen is measured to be 5.2 inches. What is the length of the pen in centimeters? (conversion relation 1 inch = 2.54 cm) 1 foot 12 inches

14. 3 3 4 4 1 1 2 2 5 5 Following units can help problem-solving Can tell if you run into problems -units don’t add right -wrongunit in final answer -use SI and you get SI -the right unit is a big part of answer (auto -1) Accuracy and Significant Figures Physical quantities are measurements -limitations on measuring device -should include uncertainty in measurement - alternative to showing +/- 0.001 m uncertainty -uncertainty built into number SIGNIFICANT FIGURES - the number of reliably measured digits plus a guess in the last 2.8 The number of digits describes ruler 2.83 3 Accuracy built into measurement 2.845 3 4 1 2 5

15. Rules for significant figures Determine number of sig figs in a measurement: 1234.56 6 sig figs rule 1 - all nonzero numbers significant 1.001042 7 sig figs rule 2 - zeros between sig figs are significant 0.004304 4 sig figs rule 3 - zeros acting as place holders insignificant (describe size of ruler) 1400000 2 to 7 sig figs ambiguous answer use scientific notation to clarify 243.040 3400.0 0.036 Working with Sig Figs using sig figs while multiplying and dividing rule 4 - use the least accurate number of sig figs in final product or quotient (least sig figs) Example: 5.347 x 0.0537 = Use 3 sig figs in final answer (least accurate measurement)