Physics 1A: Introduction to Physics and Problem Solving by G8n2Pd

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									        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

								
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