Welcome to Physics-131 Physics-I

Transcription

1 Welcome to Physics-131 Physics-I

2 TARIQ H. GILANI ASSOCIATE PROFESSOR MILLERSVILLE UNIV. ASSISTANT PROF (2002). PENN STATE UNIVERSITY STATE COLLEGE, PA (2000) POST DOC. JOHN CARROLL UNIVERSITY CLEVELAND, OH (2001) VISITING ASS. PROF. PhD ---- KYOTO UNIVERSITY, JAPAN (1997). Office: R 236 (STB) Ph tariq.gilani@millersville.edu

3 Welcome to Physics 131 Text: Physics, 11th Edition, Cutnell and Johnson Lab Notebook: Bound Lab Notebook, quad ruled, (9.75 x 7.5 ). Please bring this lab notebook to your first meeting. A scientific calculator. Reference Books: 1. Physics, 2nd Edition, Urone. 2. Physics For Scientists and Engineers, 4th Edition, Serway. 3. University Physics, 10th Edition, Young & Freedman.

4 Purpose It is an introductory algebra-based course. To become familiar with basic ideas of physics Mechanics, Heat, Energy, Waves and Sound. The primary focus will be on concepts Class Lectures Discussion Problems Demonstrations Each Lab must be satisfactorily completed to pass this course

5 Exams and Grading Two in-class exams (20% each) 40% Attendance 5 % (including recitations) Quizzes 10% Labs: 20% Final Exam 25 % Each Lab must be satisfactorily completed to pass this course

6 Labs You must complete all lab work. Missed Work If you miss a lab or exam for any reason, you must contact your instructor as soon as possible for arrangement. My phone # , tariq.gilani@millersville.edu Department office: (In case you have difficulty in finding me)

7 90-100% A % C % A % C % B % C % B % D % B % D <45% F The minimum score for any grade may be lowered based on the difficulty of quiz or examination questions.

8 Syllabus and Other Information

9 What is Phys 131? Physics Mechanics Heat and Energy Waves and Sound

10 What is Physics? Physics --- Study of basic nature of matter and the interactions that govern the behavior Observing and understanding the Physical world Physics is most basic of all sciences. It predicts how nature will behave in particular situation on the basis of experiments. Space Science Transportation Industry Electronics and Computer Science Medical Equipments Physics tells us the rules of the universe. In Physics How to see the world? Use reasoning Apply the Physical Principles To enjoy more!!

11 Measurements Experiments involve the measurements of quantities Measurements must be accurate, precise and reproducible First step --- defining units Research needs communication among international researchers Common Language --- System of Units How small an atom is? System of measurements SI CGS BE SI is most widely used Length, Mass and Time Along with few more are base Their units are basic units All other units are derived

12 MKS CGS BE Length Meter (m) centimeter (cm) foot (ft) Mass Time Kilogram (Kg) gram (g) Slug (Sl) Second (s) Second (s) Second (s) Metric Units Length meters (mm, cm, km, ) Mass Kilograms (mg, cg, g, ) Time seconds (ns, ms, ) Main Advantage Conversion within the system is quite easy 1 Kg = 1000 g 1 g = 1000 mg

13 English System Metric system NASA s Mars climate orbiter became a victim of confusion. Cost US$125 million SI System (International system): Three basic units of measurements Length or distance Meter (m) Mass Time Kilogram (kg) Second (s) SI System or MKS system

14 Kilometer (km) Mega meter (Mm) Giga meter (Gm) centimeter (cm) millimeter (mm) micrometer (µm) nanometer (nm) Power of 10 Example: 100,000 = 10 5 and = = Million = Micro = 10-6 and so on The universe is only seconds old A Million Trillion seconds 10 6 X10 12 = s To multiply 10 2 X10 6 = 10 5 X10-7 = To divide 10 2 /10 6 = 10 5 /10-7 =

15 Commonly used Metric Prefixes Prefix Figure Scientific Words Notation giga = 1000,000,000 = 10 9 = 1 billion mega = 1000,000 = 10 6 = 1 million kilo = 1000 = 10 3 = 1 thousand centi = 1/100 = 0.01 = 10-2 = 1 hundredth milli = 1/1000 = = 10-3 = 1 thousandth micro = 1/1000,000 = 10-6 = 1 millionth nano = 1/1000,000,000 = 10-9 = 1 billionth

16 Can you tell with out using calculator? How many inches are there in 6 miles? How many meters are there in 6 km? How small an atom is? Pretty small 1 Million (10 6 ) atoms if put together can not be bigger than this period at the end of this sentence First direct evidence of atom using SEM First 3-D image of an atom was obtained using STM Atoms were dragged and arranged to write the name of laboratory (IBM).

17 Whatever system of units you use --- be consistent Can not mix ---- length in ft and mass in kg A quantity is always expressed by a number and its units (if it has) Distance --- units of length Speed in units of length divided by units of time Dimensions Dimension of Length Dimension of speed = Dimension of Time Dimension Analysis First check of mathematical relation S = L T Mathematical relation must have same dimensions on both side of the equation

18 Example X is distance Dimensions L H S X = ½ v t 2 R H S v is speed t is time L L T = L T T 2 Relation is wrong X = ½ v t has the right dimensions

19 Trigonometry Basic Relations Sinθ = h o h ha Cosθ = h h Tan θ = h o a h 2 = h o 2 + h a 2 θ Adjacent h a opposite h o

20 Scalars and Vectors Scalar --- Quantity that need magnitude only Mass, Volume, Temperature Vector --- Quantity that need magnitude and direction Force, displacement Arrow --- direction Length --- magnitude 2 Km due East 4 Km due East Vector is represented by Boldface letter or Arrow on the symbol A or A A scalar is represented by italic symbol A A vector has magnitude and direction A = 2 m due west Magnitude = 2 m

21 Vector Addition Magnitude and direction When all vectors are in the same direction A = 2 m due East and B = 5 m due East Their resultant R = A + B = 7 m due East When two vectors are pointing opposite A = 2 m East Perpendicular vectors R = [A 2 + B 2 ] 1/2 A = 2 m East B Direction θ = Tan 1 ( ) A B = 5 m West => R = 3 m West B = 5 m North West Degrees North of East North R B θ A South East

22 Graphical Method Draw Vector A Draw vector B starting at the arrow of A R (= A + B) is from tail of A to head of B Measure the Length and angle of R Must use same scale Subtraction A B = A + (- B) Multiplying a vector with -1 => magnitude remains the same while direction is reversed A = 2m East -A = 2m west

23 Vector Components y-axis x-component y-component Along x-axis Along y-axis A A y A = 2 Km at 30 o North of East A x X-axis A x = A cosθ Along x-axis A y = A Sinθ Along y-axis

24 Adding by Vector components A = 2 Km 30 o North of East B = 3 Km 60 o North of East A x = 2 Cos (30 o ) B x = 3 Cos (60 o ) A y = 2 Sin (30 o ) B y = 3 Sin (60 o ) R x = A x + B x R y = A y + B y R = [R 2 x + R 2 y ] 1/2 θ = Tan 1 R ( R y x )

25 Summary Units ---- SI System (length m, Mass kg and Time s). Dimensions --- First check of Mathematical relation. Trigonometry --- Cosine, Sine and Tangent functions. Scalar and Vector Quantities. Scalar can be described completely by magnitude Vector needs direction along with magnitude to be fully described. Vector Addition and Subtraction Graphical Method Vector Components Method

26 Question Are two vectors with the same magnitude necessarily be equal?