Welcome to Physics 201

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1 Welcome to Physics 01 Today s Topics The Physics 01 Team Course Formality and Course Overview Q&A Ch 1: Physics and Measurement Physics 01 Homepage Physics Department Homepage

2 The Physics 01 Team Ø Faculty (lectures): Instructor: Prof. Yibin Pan (me), 483 CH Ø Teaching Assistants (labs, discussions): Brown, Jonathan Das, Diptaranjan Gold, David Li, Ping-Yu 301 Oxholm, Trevor Vega, Cristian Santiago Walker, Justin

3 Physics 01 Course Composition q Text: Physics for Scientists and Engineers, 9 th ed. Serway/Jewett q Lectures: TR 9:55 am q Discussion Sessions: /week. (Grading: quizzes, participation, etc.) q Labs: Mandatory. Each missing lab = - 1 letter grade level (A AB,AB B...) q Homework: ~10 problems/week online via Webassign.net q Exams: (3 middle-terms + final) q Office Hours. (Yibin Pan: :00-4:00pm Thursdays, other time by appointments, TAs: as scheduled, see course page) q Your home time: > 5 hours/week + homework. q Honor credit: see announcement (to be sent soon) q Grading: Homework: 100 pts Laboratory: 50 pts (plus missing lab penalty) Discussion: 50 pts = quizzes(0) + discussions(30). Midterms: 100 pts each Final Exam: 00 pts (Final grades are based on curved and weighted component scores) Typical curve: 0% A, 35% (AB,B), 40% (BC,C), 5% D + very few F s

4 Lectures q Style: PPT + white board + demos q Subjects: Key concepts. Tricky issues Interactive problem solving v Lectures are NOT meant to be complete. It is a supplement to your own learning Do read materials BEFORE the lecture. à Our lectures are designed with the assumption that you ve read the corresponding sections! Review materials after the lectures. Lecture notes will be posted after each lecture Effectiveness = Preview + Lecture + Review

5 q Exam Dates: Exams and Exam Policy Midterms (5:30-7:00 pm, rooms TBA) Exam 1: Monday, Oct Exam : Monday, Oct 3 Exam 3: Monday, Nov 0 Final: Thursday, Dec 1 (:45-4:45 pm, rooms TBA), cumulative. q If you have a conflict with above midterm exam dates, inform your professor (me) asap, normally at least weeks before the scheduled date. Alternative exam arrangements are granted only for valid reasons. Given the size of the class, our flexibility is very limited. Popular excuses: Academic/athletic conflicts: can be considered Medical emergency: can be considered Attending wedding/ visiting friends/family reunion plans: NOT to be considered. * Final Exam has much less flexibility to adjust. (I will be very strict)

6 q Course Web: Some Practical Issues q When sending me s: Include phrase Phy01 somewhere in the subject line. Mentioning your section # is helpful. q Homework assignments are posted each Wednesday evening and due by 11 pm of the following Wednesday. q Lecture notes will be posted after each lecture on the same day. A draft will be available the night before (can be late). Follow the links on course web. q Discussion sessions start on Thursday this (first) week q First lab starts next week ( i.e. nd week) q Please all sign up for WebAssign. ( Your TAs have for section keys. (You still need to purchase access code) 6

7 0 05/49 01 Light and Optics Electro-Magnetism Thermodynamics Heat, Temperature, Pressure, Entropy,.. Oscillation and Waves Classical Mechanics Laws of motion Force, Energy, Momentum, Physics 01 and 0 Cosmology Sub-Sub-Atomic: Elementary Particles Sub-Atomic: Nuclear Physics Many-Atoms: Molecules, solids Atomic Structure Quantum Theory Relativity Classical Modern

8 q High school math Math Background Requirements Basic formulas, linear and quadratic equations, Sine, cosine, tangent,. q Vectors q Some calculus Calculus evaluation: Are you comfortable with these? *Notations: *Definitions: *Formulas: df(x) dx d f(x),, dx *Equations and solutions: f(x)dx, b a f(x)dx df Δf lim, f(x)dx lim f ( x ) Δx dx Δx Δ df(x) d 0 x Δx 0 i i i f(x),, b f(x)dx i 1 d(, dx ax ) a f(x)dx dx 1 d( sin(x)) = ax, axdx ax =, = cos(x) dx dx df (x) = ω x f(x) = Acos( ω x +φ) dx

9 Physics and Physical Quantities q Physics is a branch of Science that covers everything at the very fundamental level Physics: Theory Observations Theory: Mathematical Relationship of Physical Quantities Observations: Measurements of Physical Quantities q A Physical Quantity ( e.g. time, mass, length...) is expressed by Numerical Value(s) + Unit A Physical Quantity without value or unit are meaningless.

10 Units of Time, Length, and Mass q Time(T), length (L), and mass(m) are three fundamental physical quantities in mechanics. From which other physical quantities can be defined (next page) q International standard (SI) units for them. SI Main SI alternative Non-SI Time s ms, µs, day, hour, Length m km, cm, mm,.. ft, yd, in,.. Mass kg g, t, lb, ounce,.. q How are they defined? Original Modern Time Solar day Atomic oscillation Length Meter Bar in France Distance light travels Mass Kilogram Block in France

11 Derived Units q Basic units can be used to construct derived units for other quantities: e.g. Area= L a *L b m, Volume = L a *L b *L c m 3 Speed = distance/time m/s Density = mass/volume kg/m 3 Force kg m/s ( Newton) Energy kg m /s ( Joule) Power kg m /s 3 ( Watt) q Units reflect dimensions of corresponding quantities: e.g. m L, m 3 L 3, kg/m 3 M/L 3, Further reading dimensional analysis q Please practice unit conversion (section 1.4) after class.

12 Significant Figures (Sig. Figures) q Every measurement has errors, one needs to be precise, but not excessively-precise. Question: A ruler has smallest scale of 1 cm. When used to measure a string of ~36 cm long, which of the following readings are improper? 36. cm 36.0 cm 36.4 cm 36. cm 36. cm Answer:. 36 is too inaccurate one more digit can be estimated 36. is over accurate the last digit can not be estimated 36., 36.4, 36.0 cm are all possibly OK (depending on reading). Note 36 cm 36.0 cm! q In measurements and in calculations only keep significant figures.

13 Rules On Sig. Figures q Rule 1: In direct measurement, keep all sure digits plus only one estimated digit. e.g. 41. cm, 3.5s,... Ø These ( sure + estimated ) digits are called significant figures (sig. figure), with the estimated one being called least sig. figure q Rule : (Definition). Number of sig. figures = number of significant digits not counting leading zeros e.g.41. nsigfig = 3, nsigfig. =, 3.0 nsigfig = 3. q Rule 3: In additions or subtractions, the least significant figure of the final result can not be more accurate than that of any operands. e.g. 13.8m +.05m-0.06m (=15.788m) =15.8m (be sure to use same unit!) q Rule 4: In multiplication or division, the N of sig. figures of the final result equals the lowest num. of sig. figures among all operands. e.g m x.05 m x 0.06 m (= ) = 1.8 m 3 Always keep all digits until final result and then perform rounding.

14 Order Of Magnitude Estimation q Often, a rough guesstimation on the physics quantities before detailed measurement is useful (and possible.) Quick quiz: How many sand grains in a palm? millions billions Quick estimation: N= total volume / sand size ~ 10 cm 3 / (0.01 cm) 3 ~ 10 million

15 One more Exercise q A solid block of iron has a volume measured as. cm 3, how many iron atoms in this block? (known: ρ= 7.86 g/cm 3, Atomic mass of iron = u, 1u = x 10-7 kg, 1g = 10-3 kg) A: 0 B: 0,000 C: x10 3 D: x10 33 q Solution: Method 1:use order of magnitude estimation. (hint: ever heard of Avogadro s number? 6.0x10 3?) Method : detailed calculation The block has mass m = ρv = 7.86 g/cm 3 *. cm 3 = 17 g Mass of iron atom = u = * x 10-7 kg/u = 9.88 x 10-7 kg Number of iron atoms in the block = 17 g /(9.88 x 10-7 kg) = 17 g x (10-3 kg /g) /( 9.88 x 10-7 kg) = 1.8 x 10 3

16 A Challenging Quiz q Measured data: Mass of Atoms (in unit u) Hydrogen 1.01 Helium 3.0 Oxygen Sodium.99 Aluminum 6.98 Iron U Ø Anything special? q Challenge All masses are (near) full numbers! Ø This strongly suggests? à Atoms are made of particles with mass = u. Facts Atom is made of: protons + neutrons + electrons M proton ~ M neutron ~ 1 u 1u = x 10-7 kg M electron << 1u

17 Resources q Your Instructor (me ) and your TAs q Practicing Engineering Problem Solving(PrEPS) for Physics 01 offered by the Engineering School. (More on this later). q The Physics Club: q Private Tutoring by Physics Graduate Students (fee):

Welcome to Physics 202

Welcome to Physics 202 Todays Topics The Physics 202 Team Course Formality and Course Overview Q&A Ch 23: Electric Charges Physics 202 Homepage http://www.physics.wisc.edu/undergrads/courses/fall2012/202/index.html