PHYS 1443 – Section 003 Lecture #1 Introduction

1. PHYS 1443 – Section 003Lecture #1 Introduction Instructor: Na’il G. Fazleev • Check roll • Lab handouts • Textbook: Giancoli “Physics” • Scientific calculator needed • Algebra, trig calculus knowledge assumed • Class for physics and engineering majors

2. Reading Assignment #1 • Chapter 1 • Introduction to Physics • Scientific Notation • Significant Figures • Units of measure and standards • Appendix A: Mathematical Review

3. Homework Solving homework problems is the best way to comprehend physics An electronic homework system will be set up for you Home work is best way to make good scores on exams Collaborations strongly encouraged  Does not mean you can copy since your questions are not identical Physics clinic is part of tuition for this course: use it! If you do not have computer access at home use UTA computer facilities

4. Why do Physics? • To understand nature through experimental observations and measurements • Establish limited number of fundamental laws, usually with mathematical expressions • Predict nature’s course • Theory and Experiment work hand-in-hand • Theory works generally under restricted conditions • Understanding laws enables us to control outcomes of natural processes: applied physics, engineering, biology, chemistry, geology, astronomy, etc. Exp.{ Theory {

5. What do we want from this class? • Physics is everywhere around you. • Understand the fundamental principles that surround you in everyday lives… • Identify what law of physics applies to what phenomena and use it appropriately • Understand the impact of physical laws • Learn how to research and analyze what you observe. • Learn how to express observations and measurements in mathematical terms: the language of science. • Learn how to express your research in systematic manner in expositional writing • Hint: Don’t be scared of PHYSICS, use its power! Most importantly, have a lot of FUN!!

6. Brief History of Physics • 500-5000 BC : • Babylonians, Egyptians and Mesoamericans predict heavenly motions • 0-500 BC • Plato and Aristotle discourage experimentation and rely upon philosophy • Archimedes develops quantitative sciences, geometry, mechanics, etc. • Aristarchus develops heliocentric theory of planets and measures distance to sun and moon (well, to about one significant figure) • Eratosthenes measures circumference of earth • Ptolemy proposes geocentric planetary system • 0-1500 AD (Dark ages): • Plato’s philosophy, religious and political powers discourage scientific method • 1500-1700 AD • Copernicus develops heliocentric planetary system • Kepler discovers accurate planetary motion laws • Galileo discovers law of gravitationally falling bodies on earth • Newton discovers 3 laws of motion, law of gravitational attraction, develops optics

7. Brief History of Physics • 1800-1900AD • Kelvin, Boltzman, Maxwell, Planck develop thermodynamics and statistics • Coulomb, Poisson, Gauss and Maxwell develop electromagnetism • 1900-2000 AD • Einstein develops theory of relativity • Schrödinger, Heisenberg, Dirac develop quantum theory • Wigner, Weinberg, Rutherford, etc. develop nuclear and elementary particle physics • Wigner, Slater, Townsend, etc. develop solid state and quantum optics • 2000- AD • Dark matter and dark energy are confirmed but not understood • Standard model lacks explanation for masses of particles (still a model, not a theory or law)

8. Scientific Method • 1. Perform impartial experiments with controlled errors • 2. Propose mathematical relationships between variables to explain results (develop a theory) • 3. Make predictions with theory and test • 4. Declare theory a law if it always works • 5. If law ever fails search for new, improved law

9. Space (x,y,z) Time (t) Mass (m) Charge (q) Spin (s) Etc (?) Forces in Nature Gravity Electricity Magnetism Weak force Strong force Not all (if any) of these forces are independent! Four forces usually cited Fundamental Quantities in Nature

10. Matter Molecule Atom Nucleus Baryon Quark (Hadron) u Electron (Lepton) High Energy Physics Structure of Matter 10-14m 10-9m 10-10m 10-15m <10-19m 10-2m Condensed matter/Nano-Science/Chemistry protons, neutrons, mesons, etc. p,W,L... top, bottom, charm, strange, up, down Atomic Physics Nuclear Physics <10-18m

11. Discovered in 1995 Directly observed in 2000 The Standard Model • Assumes the following fundamental structure:

12. { Syst. Uncertainties • Physical measurements have limited precision, no matter how carefully done, due to: • Number of measurements with different results • Quality of instruments (meter stick vs micro-meter) • Experience of the person doing measurements • Etc. • In many cases, uncertainties are more important and difficult to estimate than the central (or mean) values Stat.{

13. Uncertainties cont’d • Estimated Uncertainty • Suppose a result of a measurement is expressed as • The estimated uncertainty is 0.1cm. • Percent Uncertainty: Simply the ratio of the uncertainty to the measured value multiplied by 100: • If uncertainties are not specified, it is assumed to be one or two units of the last digit specified: • For length given as 5.2cm, the uncertainty is assumed to be about 0.1cm

14. Significant Figures • Significant figures denote the precision of the measured values • Significant figures: non-zero numbers or zeros that are not place-holders • 34 has two significant digits, 34.2 has 3, 0.001 has one because the 0’s before 1 are place holders, 34.100 has 5, because the 0’s after 1 indicates that the numbers in these digits are indeed 0’s. • When there are many 0’s, use scientific notation: • 31400000=3.14x107 • 0.00012=1.2x10-4

15. Significant Figures • Operational rules: • Addition or subtraction: Keep the smallest number ofdecimal places in the result, independent of the number of significant digits: 34.001+120.1=154.1 • Multiplication or Division: Keep the smallest significant figures in the result: 34.001x120.1 = 4083, because the smallest significant figures is 4.