Physics 218Vitaly Kocharovsky

Congratulations: You start to study Physics – the basis of our understanding of the World !!!

Reasons to know basic concepts of Physics:(a) It makes you self-reliant and stronger in this life(b) It greatly facilitates your career(c) To get the master or other degree

…

Course info: Common to all sections webpage physics218.physics.tamu.edu

Prof. Vitaly Kocharovsky: website http://faculty.physics.tamu.edu/vkochar/ office: MPHY 557; tel.: 862-1652; e-mail: vkochar@physics.tamu.edu

Lectures: Monday, Wednesday, Friday 10:20-11:10 (sec. 591-595; MPHY 204) and 13:50-14:40 (sec. 510-514,561; MPHY 205)Office hours: Monday, Wednesday, Friday 11:10–12:10 & by appointment(1) Textbooks “University Physics", v. 1 (13th edition by Young and Freedman) with Modified MasteringPhysics online homework; (2) smartPhysics – online prelectures and assessments (checkpoints);(3) WebAssign – online lab manual with write-ups turned in via WebAssign website;(4) i>Clicker2 quizzes at each lecture.

3 Midterm Exams (10%, 10%, 10%) 30%

Final Exam 30%

Laboratory (you must pass > 70%) 10%

Recitations and Recitation Quizzes 10%

MasteringPhysics Homework (>70%) 10 %

i>Clicker2 Lecture Quizzes-------------------------------------------------------------------------------------------------------------

smartPhysics Prelectures&Checkpoints

5 %---------------

5 %

Course grade is a sum of the following contributions: Note: Final exam replaces the lowest midterm, if final is higher.

Lecture Structure• You will have to routinely watch online

smartPhysics prelectures and read material of each new Chapter in the textbook

before each lecture!!!• Clicker Quizzes:

– In-class quiz at the beginning of the lecture using “clickers” to check reading assignment

– One or two mini-quizzes during and/or at the end of the lecture

• Lecture iClicker Quizzes and smartPhysics prelectures contribute 10% to your final score

Online MasteringPhysics Homework

• Weekly assignments on MasteringPhysics website (check often):– Need to get 70%+ final Homework score to pass the course

– Each late portion of HW gets 10% reduction in score PER EACH DAY LATE, so if it’s 3 days late and you did not yet start

working on you assignment, you are done with this class

• Important:– There is an option to “give up” on a problem in MP. Don’t use it!

• If you “give up” on problems, it’s irreversible and it can bring your score below 70%!

• Instead, move on to another problem and go back to this problem later (you don’t have to do them in order)

• Important: start working on HW problems early!!!

• Adaptive Follow-Up assignment for each chapter worth a total of 2 points of extra credit

• Typical semester average student’s score on HW is about 90%

Online MasteringPhysics Homework

•You have to register and access Mastering through eCampus (It doesn't require a course ID as the link within the course provides students direct access for single sign on and gradebook integration.) Also, it is possible to do MasteringPhysics homework directly at http://www.pearsonmylabandmastering.com, if ecampus does not work.

•The Introduction and Math Review is due Sunday, Sept. 7•The first homework (Ch. 1) from syllabus is due Sept. 14th, i.e., Sunday on the week of your recitation session on Ch.1•Every homework from syllabus is due Sunday on the week of your recitation session on the corresponding chapter.

How to Pass This Course• In order to pass this course you must:

– Take all the exams and the final

AND– Pass the Lab part with >70%

AND– Get 70+% on MasteringPhysics homework

AND– Have your total score above the F range

What to Expect: Physics 218• Be prepared that this is one of very hard

and time consuming classes– Need typically 10 hours of hard work a week

besides classes

• Inter-relation and intensity of the material makes it harder:– You miss one thing, but it will come and bite

you several times as the same concepts repeat throughout the course

• If you can’t afford that much time, take this class next semester

Simple schedule• We will generally follow this sequence:

- Always material first is covered in the lecture and then, in one or two weeks, it is covered in recitation

- By 11:59 pm on Sunday of the week of recitation the full HW assignment on that material has to be completed online at MasteringPhysics

• Start working on your MasteringPhysics HW early, definitely before recitation

• Work on smartPhysics prelecture&checkpoints and read material in the textbook before the lecture and prepare for lecture iClicker quizzes

How To Do Well in Physics 218• Maximize scores in all “service” categories

– Labs, recitations, HW, clicker quizzes,and smartPhysics prelectures

• Do your best on the exams– They are what really matters most to your final grade!!!

• You won’t do well on exams unless you train yourself in solving HW problems– Do problems yourself: if someone explains you the solution and

you “understood” it, that’s not good enough– If you are stuck, ask for help with a similar problem; if you had to

get help with a HW problem, solve 5 more similar ones from the book yourself

– Really helps to go beyond HW assignments and do more problems from the textbook

– You likely will have to struggle through some of the problems, but that’s the only way. You will notice that soon things will start coming to you easier

How It’s Meant to Work• Your read material of the chapter and watch smartPhysics

prelecture before lecture– The book is excellent and very useful

• In lecture I walk over the most important concepts,

fix typical misunderstandings and help you learn how to

“think right” and feel the actual logic behind the concepts– Common sense, physical intuition, lots of visual examples help– If you didn’t read the material and watch smartPhysics prelecture

ahead of time, it will not be nearly as helpful

• Do homework problems until you can do almost any problem in the book– Many will struggle in the beginning, but if you keep pushing you

will start “getting it” and there is no other way really– Recitations focus on problems, the place where you can get help

with remaining challenges• But you have to start on the homework well before the recitation

Tutoring

• Not a bad idea, but be careful:– You do not want a tutor who is solving problems

for you and trains you to solve “standard exam problems”

– You want someone who will: • spend time finding your weak spots• help you understand concepts • teach you how to solve problems• check that you figured this material by letting you

solve several problems on the same subject while watching your steps and logic

Clicker• Model called “i>Clicker 2”• Get them now before the bookstore

ran out of them!• Register your clicker by logging into

ecampus.tamu.edu with your NEO login and password or by going directly to www.iclicker.com (see instructions at the common for all sections of Physics 218 webpage physics218.physics.tamu.edu)

Clickers Setup• Turn on your clicker (press the power button)

• Set the frequency:– Press and hold the power button– Two letters will be flashing– If it’s not “AC”, press “A” and then “C”

• If everything works, you should see “Welcome” and “Ready”

Clicker Question #1

When do you think the first man will arrive on Mars?

A. Before 2020

B. Between 2020 and 2030

C. Between 2030 and 2040

D. Between 2040 and 2050

E. After 2050

We use the “AC” frequency in this classWe use the “AC” frequency in this class

Physics and Structure of NatureMechanics: Isaac Newton (1642–1727) Kinematics and Dynamics

Force

Velocity TrajectoryFields and Particles

Four fundamental forces

in Nature

Mediators: boson fields = gauge particles

Gravitational Graviton ?

Electromagnetic Photon

Weak W±, Z bosons

Strong 8 gluons

Fundamental elementary particles (fermions): Three families

6 Quarks 6 Leptons u (up)

d (down)

e (electron)

νe (neutrino)

s (strange)

c (charm)

μ (muon)

νμ (neutrino)

b (beauty)

t (top)

τ (tau-lepton)

ντ (neutrino)

Each quark exists in 3 colors (red, green, blue)

Observable particles:barions (qqq) and mesons )( qq

Proton

Neutron

ElectrodynamicsJames Clark Maxwell ( 1831 – 1879 )

Interaction of the charged particles via an electromagnetic field is responsiblefor all phenomena in chemistry, biology, medicine, and ordinary life.

Atoms and molecules in solids, liquids, gases, and plasmas

Electron

Electromagnetic fieldNucleus

1fm = 10-15m

Physics as Science:•Experimental science ≠ Math•Physical quantities (exactly defined and measurable)•Elementary constituents of matter, interactions, processes•Idealizations and models•Math equations•Range of validity Example: Classical non-relativistic mechanics

Physical quantities and units

Physical quantity Name of SI unit SI symbol

length meter m

mass kilogram kg

time second       s

frequency hertz Hz=1/s

velocity meter/second m/s

force      newton N=kg·m/s2

energy joule J=N·m

power …

watt …

W=J/s …

Name of CGS unit CGS symbol

centimeter cm

gram g

second       s

hertz Hz=1/s

centimeter/second cm/s

dyne dyn=g·cm/s2

erg erg=dyn·cm

erg/s …

g·cm2/s3

…

International System (SI) Gauss’ System (CGS) “Centimeter-Gram-Second”

Der

ived

un

its

Bas

e u

nit

s

P.S.: Never forget to specify units !!!

Example: crash of a satellite on Mars 3 m + 4 feet = 4.2 m ≠ 7 ?

Unit conversions

1. Height H= 2 m = 2 · 3.28 feet = 6.56 feet

1m=3.28 feet

2. Time of light propagation from the Sun to the Earth 8 minutes = 8·60 s = 480 s

3. Speed of a car v = 36 miles/hour = 36·1600m/3600s=16m/s

1hour=60·60s=3600s

1mile =1.6 km = 1600 m

Dimensional analysisDimensions of the physical quantities are algebraic combinations of the fundamental dimensions of length [L], mass [M], and time [ T ].

Example: x=vt ↔ [L] = [ L / T ] · [ T ]

but x ≠ vt2 since [L] ≠ [ L / T ] · [ T ]2 = [ L ] · [ T ]

Scales and units of physical quantities 1 second = 9 192 631 770 cycles of electron in cesium-133 atomic clock 1 second ≈ 1 day / (24·60·60) 1 year ≈ π·107 seconds ≈ 3·107 s 1 meter = c · (1 / 299792458) s , where a speed of light in vacuum is c=299792458 m/s ≈ 300 000 km/s. Size of an atom La~1 Angström = 1Å =10-10m ~ c·10-18s 1 light year = c·1year ≈ 3·108 m/s · 3·107 s ≈ 1016 m Size of the Universe is 13.7 billion years · c = 13.7·109 ly 1 kilogram= mass of a standard cylinder of platinum-iridium alloy =1000g Proton mass ≈ neutron mass is mp ~ 10-24 g = 10 -27 kg

Milky Way GalaxyD ~ 100 000 light years

R ~ 30 000 light years

Center of Galaxy

Distance to the nearest starProxima Centauri is L=4.2 ly

Sun

Time of space travel to Proxima Centauri T = L/v =4.2years·c/v = 4.2 years · (300 000 km/s / 30 km/s) = 42 000 years

Vector algebraScalar is a real number independent on coordinate system:mass, volume, distance, pressure, temperature, …

Tail-to-head

Vector (arrow with magnitude and direction)

is a set of components which transform

as with a basis rotation

3

1

iAA

3

1

ACA

3

1

iCi

xiy

i

Pythagorean theorem → Magnitude:

Direction:

yyxxyx iAiAAAA

v e c t o rsu n i ta reii yx

,

22yx AAA

x

yyx

A

A

A

A

A

A tan,sin,cos c o sAA x

Resolving a vector into its components:

zzyyxx BABABAA BBA c o s

Scalar (dot) product is a number

A

B

Vector (cross) product is a vector

sin

)()()(

ABBA

BBB

AAA

iii

iBABAiBABAiBABABA

zyx

zyx

zyx

zxyyxyzxxzxyzzy

Right-hand rule

BAAB