Syllabus: PHYS 1408, Principles of Physics I, Fall 2008 Welcome to the Physics 1408-002 Principles of Physics I Spring, 2009 Prof. Sung-Won Lee Dept. of Physics Texas Tech University Class room: Science Building Room 7 1/8/2009 $" %" Homework Class Time and Attendance !! !! You are expected to read the chapters indicated in the “Class Schedule” before coming to class. I will assume that you have read the material and we will discuss the concepts in class. Class attendance is strongly encouraged and will be taken randomly. Also it will be used for extra credits. "! "! "! "! Course Advice This course has several components: !! Lecture: lecture, demos and Active learning !! Reading: study the text BEFORE lecture !! Homework: individual Web based problem solving !! Labs: group exploration of physical phenomena !! SI (Supplemental Instruction) session - to be named •! The pace is fast. It is important to keep up! "! "! !! "! "! "! "! !" Homework problems are assigned and graded on the web through the commercial site MateringPHYSICS. Once you are registered, you will be able to download the assignments. The assignments are posted each Monday and are due by 11:pm on the Tuesday a week later. There are total of ~10 homework sets for this course. Pay attention to the instructions on the HW website about how HW is scored. To access MateringPHYSICS, you must register at http://www.masteringphysics.com/ Instructions are in the Student Access Kit. Your course ID is LEE2009 If you do not have the Student Access Kit which comes with a new textbook, you can purchase one on the MateringPHYSICS site. Please do this ASAP. This web site is not at TTU and you should give yourself plenty of time for submitting answers –sometimes the network can be slow or down. ! #" &" '" Exams !! !! !! !! Grades !! There will be “3” in-class exams and a final exam (see Class Schedule for dates). !! The exams are closed book. You may bring one hand-written a 3” by 5” index card with formulae, etc. Telephones, pagers, PDAs, iPods, iPhone and other gizmos are not allowed. Calculators are needed. The lowest exam grade (not the final) will be dropped since there are no makeup exams. Lab & Homework 25%, each exam 25%, and the final will count 25% towards your final course grade. Exam •!Lab, Homework 25% •!2(out of 3) in class exams 50% Final Exam •!Final Exam 25% Exam The final exam is comprehensive and is a common exam for all sections. Lab Homework There will be no make-up exams. !! (" The grading scale is A=100-90%, B=89-80%, C=79-65% and D=64-50%, F=49 to 0. )" Course Objectives Help(s) !! !! You will learn: Please do not wait until the last second to seek help. If you do not understand the material or feel that you are falling behind, seek help as soon as possible. Your instructor is available during office hours. If you cannot make it, call me or e-mail me. Dr. Sung-Won Lee, where: Sci 117, when: MWF 2:00-3:00 contact phone #: 742-3730 e-mail:: [email protected] !! TA:: Physics 1408 Lab (2 hr) /Recitation (1hr). Use their help. !! How to use Newton’s laws to solve problems with static and dynamic bodies. !! Use of conservation of energy and linear and angular momentum to solve problems. !! How to represent wave motion and solve problems about sound propagation. !! Learning Assessment: certain problems on the final exam will explicitly require facility with the course objectives and be used as learning assessment tools. *" $+" Lecture Notes! http://highenergy.phys.ttu.edu/~slee/1408/ End of Administrative Details Go to Chapter 1 $$" $%" !! !! Fundamental Science !! concerned with the basic principles of the Universe !! foundation of other physical sciences Divided into 6 major areas !! Classical Mechanics !! Relativity !! Thermodynamics !! Electromagnetism !! Optics !! Quantum Mechanics !! !! !! Our study will start with Classical Mechanics !! !! Also called Newtonian Mechanics Includes Mechanics Major developments by Newton, and continuing through the latter part of the 19th century !! !! !! !! Thermodynamics Optics Electromagnetism All of these were not developed until the latter part of the 19th century !! $!" Began near the end of the 19th century !! Phenomena that could not be explained by classical physics !! Includes theories of relativity and quantum mechanics !! Still important in many disciplines !! Wide range of phenomena that can be explained with classical mechanics !! Many basic principles carry over into other phenomena !! Conservation Laws also apply directly to other areas $&" !! Mechanics and electromagnetism are basic to all other branches of classical physics Classical physics developed before 1900 $#" !! !! !! !! !! To find the limited number of fundamental laws that govern natural phenomena To use these laws to develop theories that can predict the results of future experiments Express the laws in the language of mathematics Should complement each other When a discrepancy occurs, theory may be modified !! Theory may apply to limited conditions Example: Newtonian Mechanics is confined to objects traveling slowing with respect to the speed of light !! !! Try to develop a more general theory $'" Brief History of Physics! !! ,-"$)./"012.3456" !! !! ,-"$*./"<12.3456" !! !! 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Learn how to express observations and measurements in mathematical language! !! Learn how to express your research in systematic manner in writing! !! I don’t want you to be scared of PHYSICS!!!! !! Most importantly, let us have a lot of FUN!! $)" PHYS 1443-002, Fall 2008! Dr. Jaehoon Yu! •! Introduction, Measurement, Estimating Chapter 1 •!The Nature of Science •!Physics and its Relation to Other Fields •!Models, Theories, and Laws •!Measurement and Uncertainty; Significant Figures •!Units, Standards, and the SI System •!Converting Units •!Dimensions and Dimensional Analysis 1-1 The Nature of Science How does a new theory get accepted? •!Predictions agree better with data •!Explains a greater range of phenomena Physics and Its Relation to Other Fields Communication between architects and engineers is essential if disaster is to be avoided. 1-2 Physics and Its Relation to Other Fields Physics is needed in both architecture and engineering. Other fields that use physics, and make contributions to it: physiology, zoology, life sciences, … 1-4 Measurement and Uncertainty; Significant Figures No measurement is exact; there is always some uncertainty due to limited instrument accuracy and difficulty reading results. 1-4 Measurement and Uncertainty; Significant Figures Measured quantities are never known precisely Scientist use significant figures to indicate the level of accuracy in their measurement data. Estimated uncertainty is written with a ± sign; for example: Percent uncertainty is the ratio of the uncertainty to the measured value, multiplied by 100: %'" 1-4 Measurement and Uncertainty; Significant Figures !! 0.0075 [m] has 2 significant figures !! The leading zeros are placeholders only !! Can write in scientific notation to show more clearly: 7.5 x 10-3 [m] for 2 significant figures !! 10.0[m] has 3 significant figures !! The decimal point gives information about the reliability of the measurement !! 1500 [m] is ambiguous !! Use 1.5 x 103 [m] for 2 significant figures 3 !! Use 1.50 x 10 [m] for 3 significant figures 3 !! Use 1.500 x 10 [m] for 4 significant figures The number of significant figures is the number of reliably known digits in a number. 23.21 cm has 4 significant figures 0.062 cm has 2 significant figures (the initial zeroes don’t count) 80 km is ambiguous – it could have 1 or 2 significant figures. If it has 3, it should be written 80.0 km. %)" 1-4 Measurement and Uncertainty; Significant Figures When multiplying or dividing numbers, the result has as many significant figures as the number used in the calculation with the fewest significant figures. Example: 11.3 cm x 6.8 cm = 77 cm When adding or subtracting, the answer is no more accurate than the least accurate number used. 1-4 Measurement and Uncertainty; Significant Figures Calculators will not give you the right number of significant figures; they usually give too many but sometimes give too few (especially if there are trailing zeroes after a decimal point). The top calculator shows the result of 2.0 / 3.0. The bottom calculator shows the result of 2.5 x 3.2. Units, Standards, and the SI System These are the standard SI prefixes for indicating powers of 10. Many are familiar. !! !! !! !! !! Prefixes correspond to powers of 10 Each prefix has a specific name Each prefix has a specific abbreviation The prefixes can be used with any base units Examples: !! !! 1 mm = 10-3 m 1 mg = 10-3 g Units, Standards, and the SI System We will be work in the SI system, basic units kilograms, meters, seconds. Other systems: cgs; units are grams, centimeters, and seconds. British engineering system has force instead of mass as one of its basic quantities, which are pounds, feet, and seconds. 1-5 Units, Standards, and the SI System !! Units !! !! !! !! !! We will use mostly SI units, but you may run across some problems using British units. You should know how to convert back & forth. ! !! !! Defined in terms of a meter – the distance traveled by light in a vacuum during a given time See Table 1.1 for some examples of lengths !!" !#" Units !! SI – meter, m !! SI – kilogram, kg Defined in terms of a kilogram, based on a specific cylinder kept at the International Bureau of Standards See Table 1.2 for masses of various objects Units !! !! !! !&" seconds, s Defined in terms of the oscillation of radiation from a cesium atom See Table 1.3 for some approximate time intervals Interval! ! Time (s)! Age of universe! ! 5 x 1017! Age of Grand Canyon ! 3 x 1014! 32 years! !! 1 x 109! One year! ! 3.2 x 107! One hour! ! 3.6 x 103! Light travel from Earth to Moon 1.3 x 100! One cycle of guitar A string! 2 x 10-3! One cycle of FM radio wave! 6 x 10-8! Lifetime of neutral pi meson 1 x 10-16! Lifetime of top quark! ! 4 x 10-25! !'" 1.5 Converting Units !! !! !! !! Density is an example of a derived quantity It is defined as mass per unit volume Converting between metric units, for example from kg to g, is easy, as all it involves is powers of 10. Converting to and from British units is considerably more work. Units are kg/m3 See table 1.5 for some density values e.g , given 1 m =3.28084 ft, !! !! this 8611-m mountain is 28251 feet high. The atomic mass is the total number of protons and neutrons in the element Can be measured in atomic mass units, u !! 1 u = 1.6605387 x 10-27 kg !(" !! Useful Conversion factors: !! 1 inch = 2.54 cm !! 1 m = 3.28 ft !! 1 mile = 5280 ft !! 1 mile = 1.61 km !! Example: convert miles per hour to meters per second:" 1 mi mi ft 1 m 1 hr m = 1 ! 5280 ! ! = 0.447 hr hr mi 3.28 ft 3600 s s !*" #+" 1-6 Order of Magnitude: Rapid Estimating 1-7 Dimensions and Dimensional Analysis A quick way to estimate a calculated quantity is to round off all numbers to one significant figure and then calculate. Your result should at least be the right order of magnitude; this can be expressed by rounding it off to the nearest power of 10. Dimensions of a quantity are the base units that make it up; Written using square brackets. Example, speed, v = “distance / time” Dimensions of speed: [L/T] e.g. …. Quantities that are being added or subtracted must have the same dimensions. ! Diagrams are also very useful in making estimations. #!On-line HW: MateringPHYSICS registration #!Before the next lecture, read the text book, Chapter 2. #!Next lecture: Tuesday, 1/13 #!" ##"