Physics 8A Introductory Physicsmoller.physics.berkeley.edu/~phys8a/intro.pdf · 01/17/2007 YGK, Physics 8A Solving a Physics Problem • The process of solving a “physics problem”

Physics 8AIntroductory Physics

Prof. Yury KolomenskySpring 2007

01/17/2007 YGK, Physics 8A

What Do Physicists Do ?

• Basic answer: attempt to understand the Lawsof Nature and the Structure of the Universe Sounds grandeur, doesn’t it ?

• Different scales: space scales, time scales From subatomic particles to the entire visible

Universe From present time to the Big Bang From “fundamental interactions” to applications

(Or what I do when I am not teaching Phys8a)


Ultimate PuzzleHow do these…

…make up all this ?


Why ?• Human curiosity

Have you ever stared at the night sky and wonderedwhere it all came from ?

Or more importantly, where is it all going ? People have -- for as long as we remember.

• Don’t just take my word for it

Question #1: What is the Universe made of ?


“Spinoffs”: Discoveries Lead toApplications


Examples Close to My HeartPolarized noble gas target in myPh.D. experiment

Polarized noble gas in humanlungs (© U of Virginia)


So Why Should YOU Learn AnyPhysics ?

• You will graduate from UC Berkeley eventually We want you to be a well-educated member of society You may one day be important

• But more importantly, you will be using moderntechnology in your professional life You should understand how tools work to use them

effectively You could invent new applications And you should be confident in your knowledge

No black magic !

• Even more important: being able to “think like aphysicist”


Think Like a Physicist


Think Like a Physicist ?• To demonstrate, let’s conduct a quick poll• What is your favorite medical TV show ?

a) ERb) Grey’s Anatomyc) Scrubsd) Housee) General Hospitalf) I don’t watch TV, this class is enough

entertainment


You May Guess What I’d Pick


Think Like a Physicist• Physics relates observations to a small set of

fundamental laws Deductive reasoning Abstraction Generalization

• Physics laws describe relationships between physicalquantities The number of quantities is finite Small number of “fundamental” laws More complex relationships are derived from these

fundamental laws, iteratively• Solving a problem means finding the right

relationships, and applying them to the situation


Solving a Physics Problem• The process of solving a “physics problem” is

different from biological sciences1. Make observation (read the problem)2. Abstract the process (throw away useless info, make

simplifications, draw a picture)3. Identify concepts4. Find the relationships between knowns and unknowns

Equations5. Solve for unknowns, plug in the numbers

• The key step is #4 Hard to jump there directly This is a common “don’t know how to start” issue


Summary of Mechanics• You can’t parse this

yet, but that’s OK Every symbol here is a

concept Every line is a

relationship (equation) Together, they form a

“roadmap”, you canactually use it to solvephysics problems !

The key is not tomemorize formulae,but to learn therelationships andconcepts


Structure of the Course

• Linear progression Topics are covered in natural succession

• Two semesters Physics 8A

Mechanics Fluid statics and dynamics Waves, Optics Thermal physics

Physics 8B Electricity and magnetism Relativity Quantum physics


Introductory Physics: a Survey• “Only” 2 semesters

Will review most important phenomena Will generalize observations in a small set of

fundamental laws Physics is experimental science

• Avoid memorizing Specific knowledge: phenomena, laws, numbers Learn to apply it: problem solving Abstract thinking. Concrete applications. Think like a physicist


Learn By Doing• Five important ingredients of the course

Book: introduction and reference Lectures: observe (demos), then derive (laws) Discussion sections: name says it all

DISCUSS ! Labs

Experiment ! Homeworks

Reinforce And finally, exams

Assess


How You Should Learn• “Spiral Learning” concept

3 states to achieve knowledge1. Ignorance2. Confusion3. Understanding

One can argue, that there are several degrees of understanding.Profound understanding, requires belief or reinforcement. Wepromote the latter.

So, optimally, your sequence would be1. Read the book2. Attend lecture, take notes, ask questions3. Go to discussion section, ask questions !4. Do homework5. Return to the book to reinforce Rinse and repeat


Class Organization

• See website http://moller.physics.berkeley.edu/~phys8a


GradingFall ‘05

ABCDF


Homeworks are Important


Extra Curriculum Activities• “On the Same Page with Stephen Hawking”

Campaign promoted by the College of Letters andSciences

Shared intellectual experience: read and discussStephen Hawking’s “Brief History of Time” I would be happy to discuss the book with you (outside

of class) You may want to attend Hawking’s public lecture on

March 13


The Dan Brown Challenge• Dan Brown’s other book, “Angels and

Demons” is very loosely based on physics“facts” Your challenge: find the largest number of physics

faux pas in this bookAny false facts, statements, or situations that are simply

impossible Numbers that are wrong by more than an order of

magnitude Whoever gets the largest number of (verifiable) blunders

gets a prize from me at the end of the semester (no, it’snot a grade increase :)


What Would YOULike to Learn ?

Physics 8A Introductory Physicsmoller.physics.berkeley.edu/~phys8a/intro.pdf · 01/17/2007 YGK, Physics 8A Solving a Physics Problem • The process of solving a “physics problem”

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