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, Instructor Office Hours: Th 9: :30 AM, MH 2661 TA Office Hours: W 2:00 - 4:00 PM, Physics Tutorial Center (Mayer Hall) Course Webpage: 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 TheoryExperiment Careful observations and recording of physical phenomena Systematic variation of conditions Testing theoretical predictions Formulation of general descriptions of physical phenomena Predictions about physical phenomena at all conditions 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 = mc 2 Energy Mass Speed of Light (3*10 9 m/s)

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 Force Mass Acceleration

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 LENGTH Size of an object Distance between objects or events SI UNIT = METER MASS How much matter is in an object SI UNIT = KILOGRAM TIME How long something lasts SI UNIT = SECOND

Dimensional Analysis L*L*L = L 3 [m] = M [x] = L [t] = T Volume [V] = Velocity [v] = [x]/[t]L/T Acceleration [a] = [v]/[t](L/T)/T = L/T 2 Force [F] = [m]*[a] =M*L/T 2 m3m3 m/s m/s 2 kg*m/s 2 = N Physical Quantity Dimension SI Unit VERY IMPORTANT IN PROBLEM SOLVING!!!

Unit Conversion A = 10 m ft X m 1 m = 3.28 ft = in 1 mile = 1609 m = km What is X in meters? What is X in feet? What is the speed limit in SI units?

Coordinate Systems O O

Cartesian CoordinatesPolar Coordinates Point in space specified by distance from origin in x and y directions P = (x,y) Point in space specified by straight line distance from origin and angle of line P = (r,  )

Trigonometry Review x y X Y r  Pythagorean Theorem r 2 = x 2 + y 2 Sin  = side opposite  hypotenuse side adjacent to  hypotenuse side opposite  side adjacent to  y r x r y x Cos  = Tan  = = = = Trig Functions Sin -1 (y/r) =  Cos -1 (x/r) =  Tan -1 (y/x) =  Inverse Trig Functions YOU WILL USE THESE OVER AND OVER AND OVER AND OVER AGAIN!! GET USED TO THEM!!!

Problem Solving: 10 fool-proof steps 1) READ 2) READ AGAIN 3) DRAW DIAGRAM 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 20 o 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