welcome to physics 7a! winter 2008 prof. robin d. erbacher 343 phy/geo bldg...

Welcome to Physics 7A!

Winter 2008

Welcome to Physics 7A!

Winter 2008

Prof. Robin D. Erbacher343 Phy/Geo Bldg

[email protected]

Prof. Robin D. Erbacher343 Phy/Geo Bldg

[email protected]

Physics 7A -A/BPhysics 7A -A/BPhysics 7A -A/BPhysics 7A -A/BThis course has two instructors:

Prof. Robin Erbacher (me) rderbacher @ucdavis Ruggero Tacchi (Lead DL Instructor) rtacchi @ucdavis

You are enrolled in one of two 7A classes. 7A-C/D has lectures on Tuesdays. We are independent courses but cover the same material, so you

can attend any review session. We have a common final exam.

The final exam is Tuesday March 18th, 10:30-12:30 If you know you cannot make the final, you should take 7A in

a different quarter. There are no make-up exams.

Course Website and PolicyCourse Website and PolicyCourse Website and PolicyCourse Website and PolicyOur website will be linked to the main Physics 7 page: http://physics7.ucdavis.edu along with MyUCDavis. Please read the course policy as soon as possible and let us know if you have questions.

Academic DishonestyAcademic DishonestyAcademic DishonestyAcademic Dishonesty

Cheating of any sort is not tolerated. This includes but is not limited to:• Copying during quizzes/exams.• Taking a test for another student.• Having a friend use your clicker to register you as present when you are not.• Modifying a quiz before asking for a re-grade.

As soon as dishonesty is suspected the student is referred to Student Judicial Affairs.

Personal Response SystemPersonal Response SystemPersonal Response SystemPersonal Response SystemA.K.A - Clickers!

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

We will use these to allow you (and us) to gauge your understanding on conceptual questions during lecture.

You will receive credit for participation by answering questions. No matter whether correct or wrong.

You need your own with your own student ID (bookstore).Bring clicker to next lecture!

QuizzesQuizzesQuizzesQuizzes• We will have 5 quizzes during lectures, on alternate weeks.

• You must attend your assigned lecture time: sleeping is not an excuse to go to a different lecture.

• Your first quiz will be next week, Monday January 14th. Bring a calculator -- you may need it and we don’t have any to lend.



QRST

Green circles help identify you (name, ID).Purple circles helps them enter results accurately.We use letter “rubric” codes for partial credit scoring.

Grading PolicyGrading PolicyGrading PolicyGrading PolicyThe full course policy is in the document linked to the website, you must read this.

Quizzes: The lowest of your 5 quiz scores will be dropped for the final quiz average. There are no make-up quizzes. If you miss one, that one will be dropped.

Final Grade Determination

Your final grade is calculated two ways: 5% PRS + 45% top 4 quiz avg + 50% final exam +/- DL

OR5% PRS + 20% top 4 quiz avg + 75% final exam +/- DLThe most favorable score is used for your grade.

Your First DL…Your First DL…Your First DL…Your First DL… Discussion Labs (DLs) begin immediately after lecture today with section 1. All DLs are in Everson 266. Equipment tables are set up there.

People who are wait-listed or not enrolled in the DL:

• Don’t join a table immediately.• Collect in a corner while the TA begins business,• Then the TA will address enrollment issues.

Important

Who Am I?Who Am I?Who Am I?Who Am I?I’m an Associate Professor of Physics (tenured) here at Davis. My research is in elementary particle physics.

• I’m from Pacifica, CA (well, Los Angeles originally)

• I went to U.C. San Diego for undergraduate, majoring in physics, with minors in Lit/Writing and Poly Sci.

• I went to graduate school at Stanford University. PhD thesis at SLAC (Stanford Linear Accelerator Center). “Precision Measurement of the Spin Structure of the Proton”

• Postdoctoral Research Associate at Fermilab (Fermi National Accelerator Lab) in Chicago suburbs.

• Professor: UC Davis Physics department.

Particle Physics ResearchParticle Physics ResearchParticle Physics ResearchParticle Physics Research

protons anti-protons

+

Fermilab: (Fermi National Accelerator Lab), near Chicago.

CERN: (Conseil européen pour la Recherche Nucléaire)

Fermilab

What is Physics?What is Physics?What is Physics?What is Physics?We begin with the child-like wonder about our everyday world.• Why is the sky blue?• Is there anything colder than ice?• How does a light switch work?• How do magnets work? • How do planes fly?• Why does scuffing your feet on carpet “zap” you?• Why can some people play pool with great precision?



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Physics: Find Common Principles Physics: Find Common Principles to Explain Many Phenomenato Explain Many Phenomena

Physics: Find Common Principles Physics: Find Common Principles to Explain Many Phenomenato Explain Many Phenomena



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Some of these principles are the same: Depends on the question asked!



QuestionQuestionQuestionQuestionHow do we know that MEarth = 5.98 x 1024 kg?



“Look it up in a book” misses the point.

Treat the Earth, planets, and the sun as systems that obey the same principles (or models) as mundane objects such as apples and blocks.

Models of the UniverseModels of the UniverseModels of the UniverseModels of the UniverseUsing similar principles and models we can measure the mass of stars and galaxies:

• We know how much stars weigh (roughly).• We know how much light stars give off (roughly).• … So we can “count” the stars and figure out how much of the mass is “stuff we know”.

But “stuff we know” is only ~<3% of the mass of the galaxy!

Lots of discoveries to make!

Physicists…Physicists…Physicists…Physicists…

•Wonder about the world around them.•Try to explain phenomena using a few principles (models).•We cannot “pick and choose” when an explanation works

What is the world made of?What holds the world together?

Where did we come from?

•While our models may not always hold true, we have some understanding of when they’re valid.

Physics is taking this approach in the physical world!

What is Physics 7?What is Physics 7?What is Physics 7?What is Physics 7?Physics 7 is a 3-quarter series of physics classes, typically taken by bio-science and other non-physical science majors.

• Physics 7A: Energy conservation, thermodynamics, particle models of matter. • Physics 7B: Classical Mechanics, rotational motion, fluids, circuits. • Physics 7C: Wave phenomena, optics, electricity and magnetism, the atom and modern quantum mechanics.

What is Physics 7, really?What is Physics 7, really?What is Physics 7, really?What is Physics 7, really?Physics 7 is a new approach to teaching and learning introductory physics. It involves:

• Learning by doing.• Active learning.• Application of models to various physical systems.• Learning by exploration in a small group.• Using a chalkboard and discussing openly.

It will require your active participation!

Your DL grade will reflect this. (DL Instructors will tell you more about their expectations.)

The Physics 7 ApproachThe Physics 7 ApproachThe Physics 7 ApproachThe Physics 7 ApproachActive learning is key to “getting” the concepts in Physics 7 and being able to apply them to new situations.

• Most of your learning will take place in the Discussion Labs (DLs), so attendance is mandatory.

• The lecture will provide a framework (and in some cases a review) for the subject material, and will allow more explanation and demonstration of concepts.

• Your DL instructor will only give you guidance and pointers about the right way of thinking-- they will not in general solve the problems for you!

• To solve the problems, interact strongly with your small student group (4-5 people) and the DL section (the whole class: ~25 people).

A Slightly Different PhilosophyA Slightly Different PhilosophyA Slightly Different PhilosophyA Slightly Different Philosophy

We do not emphasize getting the right answer, though that is important too.

In DLs, FNTs (For Next Times), quizzes, and the final, we are looking for indications that:

1) The problem is clear to you.

2) You are arriving logically to the next step.

3) You clearly understand which model to apply to the problem at hand, why, and how to do it.

Physics 7A StrategyPhysics 7A StrategyPhysics 7A StrategyPhysics 7A Strategy

• Learn to think logically and to make valid arguments when describing a system or solving a problem.

• Learn to apply analytical principles and logic to understand problems and devise solutions.

• Learn to reason with models and explain the world around us.

We are not here to memorize equations or rote procedures in problem-solving.

ModelsModels

The Bohr Model of the AtomThe Bohr Model of the AtomThe Bohr Model of the AtomThe Bohr Model of the Atom

“The atom is nothing but a little electron orbiting around a proton.”



Examples of ModelsExamples of ModelsExamples of ModelsExamples of Models

Models in Physics:• Newtonian mechanics• Standard Model of particle physics• Standard Model of cosmology

Models in Biology:• Protein-lipid interaction model• Protein-protein interaction model

(Don’t ask me about these last two!)

A Model: DefinitionsA Model: DefinitionsA Model: DefinitionsA Model: Definitions





• Models can help us organize our thinking, can contain other models, and can be very useful.• Models also have limitations: experiment is the final judge.

Models in Physics 7AModels in Physics 7AModels in Physics 7AModels in Physics 7A

• Three-phase model of matter

• Energy-interaction model

• Mass-spring oscillator

• Particle model of matter Particle model of bond energy Particle model of thermal energy

• Thermodynamics

• Ideal gas model

• Statistical model of thermodynamics

We start withThese two…

But First…..

Let’s Talk EnergyLet’s Talk Energy

Conservation of EnergyConservation of EnergyConservation of EnergyConservation of Energy• Energy is both a thing (quantity) and a process. You & I contain energy, as do the chairs you sit on and the air we breathe. • We cannot see it, but we can measure the transformation of energy (or change, E).

Conservation of EnergyEnergy cannot be created nor destroyed, simply

converted from one form to another.

• If the energy of an object increases, something else must have given that object its energy.

• If it decreases, it has given its energy to something else. Energy transfer is done through Heat or Work.

NOTE: The total energy of a closed system remains constant!This course is about energy, how its transferred, how its conserved.

Remember Particle Physics?Remember Particle Physics?Remember Particle Physics?Remember Particle Physics?

Protons + anti-protons New particles!

Fermilab

Conservation of EnergyEnergy cannot be created nor destroyed, simply

converted from one form to another.

E=Mc2

!

x

x

Three Phase Model of MatterThree Phase Model of MatterThree Phase Model of MatterThree Phase Model of Matter

The basic idea

Three Phase Model- DefinitionsThree Phase Model- DefinitionsThree Phase Model- DefinitionsThree Phase Model- Definitions

Pure substances: one chemical substance -water vs. unpasteurized apple cider

Phases: solid, liquid, and gas

Temperature: measure of the hotness of something

Energy: here, it is something that is transferred in the form of heat or work

Phase change temperature: the unique temperature at which a pure substance changes from one phase to another

Graph of Ice to SteamGraph of Ice to SteamGraph of Ice to SteamGraph of Ice to Steam

Stage A: This is the very cold ice starting to warm up Here, it goes from -30 to 0. It is all still ice. Energy is added, but no phase change.


Stage B: Ice is now at zero degrees and heat (energy) is still being added. As energy is added, the temperature is constant and stays at zero until all ice is gone. Solid/liquid co-exist. All the energy went into melting the ice, not changing temperature.


Stage C: It is now all water and heat (energy) is still being added. The heat goes into raising the temperature of the water. No phase change.


Stage D: The water is now at the boiling point (100 deg) and heat is still being added. The energy goes into changing the water into steam. No temperature change. This is another mixed phase. Liquid/Gas co-exist.


Stage E: All of the water has now turned into steam. As heat is added, the temperature increases. No energy goes into changing phase, all into making the pure substance hotter.

Phase Changes - a recapPhase Changes - a recapPhase Changes - a recapPhase Changes - a recap

You take ice out of the freezer at -300C and place it in a sealed container and slowly heat it on the stove. You would find:

• the temperature of the ice rises,

• remains fixed at 00C for an extended time while it is a mixture of ice and water,

• the temperature rises again after it all melted,

• remains fixed at 1000C for an extended time while it is a mixture of liquid and gas,

• the temperature rises again after it is all gas (steam).

Next Time: Heat Capacity, Specific Heat, Energy Diagrams

Next Time: Heat Capacity, Specific Heat, Energy Diagrams

Reminder…Reminder…Reminder…Reminder…

Next lecture contains a quiz.

Bring your calculator.

Bring your Clicker for participation credit.

welcome to physics 7a! winter 2008 prof. robin d. erbacher 343 phy/geo bldg...

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