VIEWS: 2 PAGES: 14 POSTED ON: 9/29/2012
Physics 1A: Introduction to Physics and Problem Solving Instructor: Dr. Rae Robertson Lectures: MTWThF 8:00 - 9:20 AM Course Logistics Lectures: MTWTHF 8:00 - 9:20 AM, WLH 2005 Problem Sessions: Th 2:00 - 3:20 PM, WLH 2204 TA: James Wilson, wilsja@gmail.com Instructor Office Hours: Th 9:30 - 11:30 AM, MH 2661 TA Office Hours: W 2:00 - 4:00 PM, Physics Tutorial Center (Mayer Hall) Course Webpage: http://physics.ucsd.edu/students/courses/summer2008/managed/physics1a/ Textbook: College Physics, Vol I, Serway & Faughn Grading: Final: 40%, Quizzes: 60% (20% each), Questions of the Day: 20%, Weekly Homework Sets: Ungraded NO makeup quizzes or Final! Know your student code! Lecture Attendance: Mandatory! You can’t learn unless you show up. Please bring 3x5 notecard to each lecture for daily questions. What is Physics?? The most incomprehensible thing about the world is that it is comprehensible. -Albert Einstein Observations, Theories & Predictions Physics Experiment Theory Careful observations and recording Formulation of general descriptions of of physical phenomena physical phenomena Systematic variation of conditions Predictions about physical phenomena at all conditions Testing theoretical predictions Problem Solving Understanding HOW physical systems/phenomena work and WHY it behaves as it does Mathematics: The Language of Physics The Book of Nature is written in mathematical characters, without whose help it is impossible to comprehend a single word….. -Galileo Descriptions of physical phenomena = mathematical equations Variables = physical quantities/characteristics of system E = mc2 Speed of Light Energy (3*109 m/s) Mass Mathematics: The Language of Physics The Book of Nature is written in mathematical characters, without whose help it is impossible to comprehend a single word….. -Galileo Descriptions of physical phenomena = mathematical equations Variables = physical quantities/characteristics of system F = ma Acceleration Force Mass Dimensions and Units Many ways to describe an object or system Dimension = physical nature of quantity Three fundamental dimensions can be used to describe many types of phenomena/physical systems MASS TIME LENGTH Size of an object Distance between How long How much matter something lasts objects or events is in an object SI UNIT = METER SI UNIT = SECOND SI UNIT = KILOGRAM Dimensional Analysis [x] = L [m] = M [t] = T VERY IMPORTANT IN Unit Physical QuantityDimension SI PROBLEM SOLVING!!!m Volume [V] = L*L*L = L 3 3 Velocity [v] = [x]/[t] L/T m/s Acceleration [a] = [v]/[t] (L/T)/T = L/T2 m/s2 Force [F] = [m]*[a] = M*L/T2 kg*m/s2 = N Unit Conversion 1 m = 3.28 ft = 39.37 in 1 mile = 1609 m = 1.609 km A = 10 m2 3.28 ft Xm What is X in meters? What is the speed limit in SI units? What is X in feet? Coordinate Systems + - O + - Coordinate Systems Cartesian Coordinates Polar Coordinates Point in space specified by Point in space specified by distance straight line distance from origin from origin in x and y directions and angle of line P = (x,y) P = (r,q) Trigonometry Review Trig Functions Y Sin q = side opposite q = y hypotenuse r YOU WILL USE THESE r Cos q = side adjacent to q AND OVERyAND OVER hypotenuse x = r q OVER AND OVER q Tan q = side opposite = y side adjacent to q x x AGAIN!! X Inverse Trig Functions Sin-1 (y/r) = q GETy USED TO THEM!!!q Pythagorean Theorem 2 2 r =x + 2 Cos (x/r) = -1 Tan-1 (y/x) = q 1) READ 2) READ AGAIN Problem Solving: 3) DRAW DIAGRAM 10 fool-proof steps 4) CHOOSE/LABEL COORDINATE SYSTEM 5) LABEL PHYSICAL QUANTITIES 6) IDENTIFY ALL KNOWN & UNKNOWN QUANTITIES 7) CHOOSE EQUATIONS 8) SOLVE EQUATIONS 9) INSERT KNOWN QUANTITIES 10) CHECK!! Questions of the Day 1) If an equation is not dimensionally correct, does that mean that the equation can’t be true? A) YES B) NO 2) You walk 10 m in a direction 20o North of East, you want to know how far North you have traveled… What trig function would you use to figure this out? A) Sine B) Cosine C) Tangent