UCSD Physics 12

Physics 12: Energy and the EnvironmentPhysics 12: Energy and the Environment

A Physics Perspective on our Society’s NeedsA Physics Perspective on our Society’s Needs

Tom MurphyTom Murphy

UCSD Physics 12

Spring 2013 2

Course ObjectivesCourse Objectives

1.1. Become well informed on the topic of energy Become well informed on the topic of energy and its use in our society, so that you may and its use in our society, so that you may participate in the national debate and make smart participate in the national debate and make smart decisionsdecisions

2.2. Understand the physical concept of energy and Understand the physical concept of energy and learn to identify it in the world around uslearn to identify it in the world around us

– kinetic energy (energy of motion)– gravitational energy– chemical energy– thermal energy (a form of kinetic energy)– light (radiative) energy– nuclear energy

UCSD Physics 12

Spring 2013 3

Course Objectives, continuedCourse Objectives, continued

3.3. Comprehend Energy ConservationComprehend Energy Conservation– loss-less exchange of energy between forms

– never created or destroyed—just converted/exchanged

4.4. Learn to calculate energy content/conversionLearn to calculate energy content/conversion– most quantitative part of course

– forms foundation for all that follows

– applications to familiar everyday systems

– math isn’t hard, but units can be a pain

UCSD Physics 12

Spring 2013 4

Course Objectives, continuedCourse Objectives, continued

5.5. Learn about the energy usage in our livesLearn about the energy usage in our lives– where we get it, where/how we use it, how we

distribute it– some discussion of why we need so much energy

6.6. Discuss the future of energy productionDiscuss the future of energy production– fossil fuels can’t last forever (or even very long)– alternative production of energy

7.7. Discuss the side-effects of energy productionDiscuss the side-effects of energy production– environmental issues– sociological issues

UCSD Physics 12

Course StruktureCourse Strukture

• Homework 3 times per week (due every lekture)Homework 3 times per week (due every lekture)• 2 quizzes per week2 quizzes per week• 5 midterms5 midterms• 2 final exams2 final exams• oh—and a 20 minute presentationoh—and a 20 minute presentation

• highest grade is B-highest grade is B-

• In kase you hadn’t guessed… April Fools!In kase you hadn’t guessed… April Fools!

Spring 2013 5

UCSD Physics 12

Spring 2013 6

Course StructureCourse Structure

• Class meeting times:Class meeting times:– Lectures in York 2622 MWF 3:00–3:50

• PowerPoint presentations– Lecture materials will be made available on the web

• Interactive Transmitter to promote discussion/learning

• Demonstrations

• Exams: Midterm Mon. May 6; Final Wed. June 12

– Discussion section meets in CSB 005, Wed 4:00–4:50 PM• Opportunity for discussions on course material, exam prep, etc.

• Math background and exercises

• Work out example problems and questions

UCSD Physics 12

Spring 2013 7

ResourcesResources• Your Fellow Students!Your Fellow Students!

– Encouraged to work together in class and on homework (but not on quizzes or exams!). BUT COPYING PROHIBITED: use own words

• Professor : Tom MurphyProfessor : Tom MurphyOffice in SERF building, Room 336, office hours Th 1:30–2:30 PM, or by

appointment, 858.534.1844, tmurphy@physics.ucsd.edu

• Teaching Assistant: Matthew HaslingTeaching Assistant: Matthew HaslingOffice hours: Thursday, 2:30−3:50, SERF 434E-mail: mhasling@physics.ucsd.edu

• Web: Web: physics.ucsd.edu/~tmurphy/phys12/• TED site (quizzes, discussion board, etc.)TED site (quizzes, discussion board, etc.)• Physics Tutor Center: M–Th 3–8 PM, 2Physics Tutor Center: M–Th 3–8 PM, 2ndnd floor Mayer Hall floor Mayer Hall• Text:Text:

– Energy and the Environment, 2nd edition Ristinen and Kraushaar

UCSD Physics 12

Spring 2013 8

GradingGradingWeightWeight FormatFormat DueDue CommentsComments

20%20% HomeworkHomework

(drop 1)(drop 1)

Fri, in classFri, in class no late HWno late HW

work together, but NO work together, but NO COPYINGCOPYING

15%15% Quizzes (drop 1)Quizzes (drop 1) Friday, by Friday, by midnightmidnight

via WebCTvia WebCT

up to 15%up to 15% Class Particip.Class Particip. every lectureevery lecture via transmitter systemvia transmitter system

<30%*<30%* Midterm*Midterm* May 6 (Mon)May 6 (Mon) 3:00 PM, in class3:00 PM, in class

<35%*<35%* Final*Final* June 12 (Wed)June 12 (Wed) 3:00 PM3:00 PM

* Midterm and Final may count for as little as 15% or 20%, respectively, given extent of classroom participation and worst exam performance. Example: if you have 60% of theparticipation credit and bomb the final, the midterm still counts 30%, but the final willcounts 9% less, or 26% instead of 35%−the other 9% filled in by participation credit.

UCSD Physics 12

Spring 2013 9

What’s with this transmitter business?What’s with this transmitter business?• A part of your grade (up to 15% participation) A part of your grade (up to 15% participation)

comes from the interactive transmittercomes from the interactive transmitter– using iClicker

• Promotes:Promotes:– interaction, attention, investment in class/answer

– feedback for both student and professor

– thinking learning

• Timeline:Timeline:– Start using today

– Credit starts Friday

UCSD Physics 12

Spring 2013 10

How Much !?How Much !?

• The first part of the course is the most The first part of the course is the most quantitative, but the math itself is straightforwardquantitative, but the math itself is straightforward– just +, −, ×, ÷, and a bit of xy

• Don’t let it psych you out when you see it…Don’t let it psych you out when you see it…• I’d like you to develop a healthier relationship I’d like you to develop a healthier relationship

with quantitative analysiswith quantitative analysis– numbers can be less rigid than you think

– cut loose, and allow π = 10/3 = √10 = 3

– estimates don’t have to be exact to be useful

UCSD Physics 12

Spring 2013 11

ExpectationsExpectations

• Attend lectures and discussion sectionAttend lectures and discussion section• Participate!Participate!

– If it doesn’t make sense, ask! Everyone learns that way.– Don’t be bashful about answering questions posed.– In-class voting system should make this fun

• Do the work:Do the work:– It’s the only way this stuff will really sink in– exams become easy

• Explore, think, ask, speculate, admire, Explore, think, ask, speculate, admire, enjoyenjoy!!– Bring interesting topical ideas (recent news) to class

UCSD Physics 12

Spring 2013 12

Any Questions on Course Structure?Any Questions on Course Structure?

UCSD Physics 12

Spring 2013 13

Course Preview: the Big PictureCourse Preview: the Big Picture

• We use We use a heck of a lota heck of a lot of energy of energy– primitive society uses < 100 W of power per person

– our modern society burns 10,000 W per person

– surely not in our homes! Where is this going on?

• Energy availability has enabled us to focus on Energy availability has enabled us to focus on higher-level issues as a societyhigher-level issues as a society– art

– science

– home shopping network

UCSD Physics 12

Spring 2013 14

Once upon a time…Once upon a time…• Long ago, almost all of our energy came Long ago, almost all of our energy came from from

foodfood (delivering muscle power), and almost all our (delivering muscle power), and almost all our energy went into energy went into securing foodsecuring food for ourselves for ourselves

• Enter the work animal, supplementing our muscle Enter the work animal, supplementing our muscle power and enabling larger-scale agriculturepower and enabling larger-scale agriculture

• Next burn wood to run boilers, trainsNext burn wood to run boilers, trains• 150 years ago, muscular effort and firewood 150 years ago, muscular effort and firewood

provided provided mostmost of our energy of our energy—and today this is —and today this is less than 1% of the storyless than 1% of the story

• Today, more energy Today, more energy goes intogoes into growing/harvesting growing/harvesting food than food than comes out ofcomes out of food!food!

UCSD Physics 12

Spring 2013 15

The Great Energy DisparityThe Great Energy Disparity

Many countries in the world lie in this quarter-circle!!

UCSD Physics 12

Spring 2013 16

We live in a special time and place…We live in a special time and place…

• We use almost 100 times the amount used by the We use almost 100 times the amount used by the poorest inhabitants of the worldpoorest inhabitants of the world

• This phase has only lasted for the last century or soThis phase has only lasted for the last century or so• Most of our resources come from fossil fuels Most of our resources come from fossil fuels

presently, and this has a short, finite lifetimepresently, and this has a short, finite lifetime

UCSD Physics 12

Spring 2013 17

Global Energy: Where Does it Come From?Global Energy: Where Does it Come From?SourceSource 10101818 Joules/yr Joules/yr Percent of TotalPercent of Total

Petroleum*Petroleum* 158158 40.040.0

Coal*Coal* 9292 23.223.2

Natural Gas*Natural Gas* 8989 22.522.5

Hydroelectric*Hydroelectric* 28.728.7 7.27.2

Nuclear EnergyNuclear Energy 2626 6.66.6

Biomass (burning)*Biomass (burning)* 1.61.6 0.40.4

GeothermalGeothermal 0.50.5 0.130.13

Wind*Wind* 0.130.13 0.030.03

Solar Direct*Solar Direct* 0.030.03 0.0080.008

Sun Abs. by Earth*Sun Abs. by Earth* 2,000,0002,000,000 then radiated awaythen radiated away* Ultimately derived from our sun Courtesy David Bodansky (UW)

UCSD Physics 12

Spring 2013 18

Energy is cheap! So what’s the problem?Energy is cheap! So what’s the problem?

• We spend about $9/day, or $3,200/yr per person We spend about $9/day, or $3,200/yr per person on energy in the U.S.on energy in the U.S.– about 16% of GDP

– saves us much more than 16% of our time (labor-saving devices, transportation, etc.)

• But we’re running through our resources at a But we’re running through our resources at a phenomenal ratephenomenal rate– let’s see if this lasts even another hundred years!

• Our world will see a profound change in the next Our world will see a profound change in the next century as we adjust to a world without gasolinecentury as we adjust to a world without gasoline

UCSD Physics 12

Spring 2013 19

Still fuzzy on the concept of energy?Still fuzzy on the concept of energy?

• Don’t worryDon’t worry—we’ll cover that in great detail in —we’ll cover that in great detail in the coming weeksthe coming weeks

• Energy is defined as the Energy is defined as the capacity to do workcapacity to do work• But what is But what is workwork??

– we’ll get to this in the next lecture

• At some level,At some level, I I don’t know what energy is: why don’t know what energy is: why there is such a thing, why it’s conserved, where it there is such a thing, why it’s conserved, where it all came from, etc. all came from, etc. – these are deep and interesting questions that some

physicists try to understand

UCSD Physics 12

Spring 2013 20

Why am I worried?Why am I worried?

• I am spooked by my recent “predictions” that have come I am spooked by my recent “predictions” that have come truetrue– thought housing would go down 50% (and sold early 2006!)– claimed in summer 2008 that I wouldn’t be surprised if the stock

market lost half its “value”

• Now I can’t shake my concerns over our energy Now I can’t shake my concerns over our energy dependence and where declining resources will take usdependence and where declining resources will take us– and I blame it on physics 12!

• Otherwise normally optimist, problem solverOtherwise normally optimist, problem solver• The The good newsgood news: we : we cancan physically get through this physically get through this• The The bad newsbad news: the good news is only possible if people are : the good news is only possible if people are

educatededucated and seek and seek long-termlong-term over short-term gains over short-term gains– part of why Physics 12 may be the most important thing I do

UCSD Physics 12

My Personal TrajectoryMy Personal Trajectory

• Ever since teaching Physics 12 in 2004, I have:Ever since teaching Physics 12 in 2004, I have:– devoted a great deal of time into understanding the

challenges that face us

– built my own solar photovoltaic off-grid system

– measured everything energy-related in my house

– started gardening, replaced grass with CA natives• also rainwater catchment for watering garden

• chickens soon!

– reduced energy profile dramatically, so now < 1/5th the energy footprint of typical San Diegans

– started a blog, Do the Math, with > 2.5 million hits

Spring 2013 21

UCSD Physics 12

Spring 2013 22

AssignmentsAssignments

• Check out the course web page:Check out the course web page:– physics.ucsd.edu/~tmurphy/phys12/

• Reading:Reading:– Chapter 1 of Ristinen and Kraushaar– also read the Appendix– optional: read Galactic Scale Energy post on Do the Math (DtM)

• First homework will be due Friday, April 12First homework will be due Friday, April 12– see main course website for assignment

• First quiz by Friday (midnight), April 12First quiz by Friday (midnight), April 12• Transmitter use (iClicker) starting Friday, April 5Transmitter use (iClicker) starting Friday, April 5• Get established on TEDGet established on TED

– see course website for tips on getting connected