Physics 1070                  Prof. A.M. Saperstein           Environmental Physics

Interactive Questions

Name_________________________________________e-mail address_______________

Friday, September 10, 1999

 (1) “injustice is preferable to total ruin”. Agree or disagree? Back up your opinion with examples.
(2) Cheap energy is a good thing for all. Agree or disagree? Back up your opinion with examples
(3) You think and act as if the world were infinite. Agree or disagree? Why?
(4) Suppose you wished to allot 10 square meters of the earth’s surface to each living person.  How many people could the earth then hold?  How long would it take to reach such a population, given a population doubling time of 35 years?  How much solar energy would be available for each person?  How much solar energy is available for each member of the earth’s present population?
(5) What fraction of the earth’s present population could be supported if all food were obtained by “hand labor”?
(6) Suppose each of the 8 planets of our solar system were equally inhabitable.  Given a human population doubling time of 35 years, and assuming nothing to prevent emigration of earthlings to the other planets, starting from now, how long would it take before  each planet had a population equal to  the earth’s present population?
Your Answers:

Group Answers:

(on reverse side) Any questions you want discussed?

Monday, September 13, 1999

 (1) Leaving downtown Detroit at noon, I arrive in Lansing at 2pm. What was my “average velocity”?
(2) Ten seconds after the light changes from red to green, a car which had been stopped at the light is traveling 60 km/ hr in a northeast direction; what was its average acceleration?
(3) A car, traveling at a constant speed of 75 km/hr, changes its direction of travel from due north to due west along a curve whose radius is 0.5km; what was its average acceleration?
(4) Suppose the car in parts (2) and (3) has a mass of 1000 kg; what was the average “force” acting upon the car in each of these parts?  Suppose you, the driver, has a mass of 75 kg; what force acts upon you in each case?
(5) How much does the car “weigh”? How much do you “weigh”?
(6) How much “work” is being done on the car in part (3)? What is doing the work?
(7) How much “work” is being done on the car in part (2)? What is doing the work?

Wednesday, September 15, 1999

 (1) What is “energy”? Give some examples.
(2) A 1000 kg car goes from rest to 100 km/hr in a straight horizontal direction; how much work was done upon it?
(3) I carry a 15 kg backpack from the bottom to the top of a 1500 meter high mountain; how much work have I done on the backpack? Suppose my mass is 75 kg; what is the total work that I have done?
(4) I drop a 0.5 kg loaf of bread from a height of 2 meters above the floor to the floor; assuming no friction, how fast is the loaf moving when it hits the floor?  In reality, will the loaf be moving faster, slower, or the same as in the frictionless case?  Why?
(5) A 1 kg hammerhead, moving at 5 meters per second, hits a nail, drives it 2 centimeters into a wooden board, and comes to a stop.  What is the average force with which the wood resisted being penetrated? What is the average force of friction between wood and nail?
(6) I throw a 1/2 kg ball straight up above me. If the ball leaves my hand with a speed of 8 meters per second, how much work did I do on the ball?  Ignoring air resistance, how high above me will the ball rise? How will this answer change when friction is taken into account?

Friday, September 17, 1999

 (1) What is the “mechanical advantage” of the lever in Fig. 3.5 of the text?
(2) What factors would determine the “efficiency” of the lever in Fig. 3.5 of the text?
(3) How many kilograms could be heated through  a temperature difference of 50  C by the energy contained in your daily diet?
(4) What is the maximum possible rise in temperature of water going over a 10 meter high dam?
(5) A 60 kg woman hikes up a 500 meter high mountain in two hours.  How much average power did she require for the climb? Was this the total power she generated?
(6) Estimate your “BMR”; how does this compare with the energy content of your usual daily diet?

Wednesday, September 22, 1999

 (1) An electric charge of one coulomb has passed through a conducting wire.  How many electrons have passed through the wire? If this has occurred in 0.5 seconds, what is the value of the electrical current which has flowed through the wire?
(2) Suppose the distance between two charges is tripled. How does the force between them change?
(3) I have two charged bodies separated by a fixed distance.  I double the charge on one of the bodies, triple it on the other.  How does the electrical force between them change?
(4) Suppose I move a body having an electrical charge of 0.5 coulombs between two points in space differing in potential by 120 volts. How much work has been done?
(5) An electric current of 0.3 amperes flows through a potential difference of 1.5 volts in a flashlight.   How much power has been liberated? What supplied the energy?  What happens to this energy/
(6) How much power is liberated when a 5 ampere current flows through a 6 ohm resistor?  What potential difference would be required to produce such a current?

Friday, September 24, 1999

 (1) You know that electrical charge can be separated so that you may have a purely positively of a purely negatively charged body. Can you do the same with magnets, i.e., can you have a body which is purely north pole or one which is purely south pole?
(2) Describe the similarities and the differences between an electrical generator and an electric motor.
(3) What are the problems with very high voltage electrical transmission lines?  Given these problems, why do we use such lines?
(4) Why are transformers important?  How are they used?

Monday, September 27, 1999

 (1) The average speed of the electrons in the wire of an electrical circuit may typically be 10 mm/s. Yet your light bulb lights the instant you throw the switch.  How is this possible?
(2) How can any energy be transmitted by an AC circuit when the electrons just slosh back and forth 60 times a second?.
(3) How do electric and magnetic fields differ in the effects they have on electric charges?
(4) How do electric charges influence electric and magnetic fields?
(5) How do electric and magnetic fields influence each other?

Wednesday, September 29, 1999

 (1) How much energy was used in the U.S. in 1975? How did you obtain your answer?
(2) What was the doubling time of the U. S. population in 1860?  In 1980?  How long did it actually take the 1860 population to be doubled?
(3) Which curve -the exponential or the logistic - would be more appropriate to discuss world population?
(4) What is “price elasticity” and how does it effect consumption?  Can you think of anything that would have zero or positive elasticity?
(5) How would population and electric price elasticity projections effect electric power consumption projections?

Friday, October 1, 1999

 (1) In 1992, the ratio of petroleum use to natural gas use in the U.S. was? How much energy was used for residential purposes in the U.S. in 1991?
(2) Why did we change from DC electric utuilities to AC utilities?  What were some of the consequences?
(3) How much more electrical power is used at peak than at minimum in the winter? in the summer?
(4) What is “base load” and why is it more economical to produce?
(5) What are the advantages, the disadvantages, of building ever bigger tankers?
(6) How does Fig 6.7 demonstrate the “economies of scale”?
(7) According to Table 6.5, gas turbines are the cheapest to build; why, then, aren’t they used for base load?
(8) What are the differences between “hard” and “soft” energy paths? Advantages and disadvantages of each?  Give examples of each.
(9) What are the advantages and disadvantages of graphs with respect to tabular data?

Monday, October 4, 1999

 (1) List and discuss some similarities and some differences between atoms and our solar system.
(2) How many electron volts are in one kilocalory?
(3) What do  atomic “shells” have to do with the periodic table of the elements?
(4) What is ionization? What does it have to do with chemical combination?
(5) Define: exothermic, endothermic, catalysis, enzyme, chlorine-ozone cycle.
(6) What is the relation between photosynthesis and fossil fuels?

Wednesday, October 6, 1999

 (1) What are the differences between “temperature”, “heat”, “internal energy”, and “thermal energy”? Between the Celsius and the Kelvin scales?
(2) What is the “first law of thermodynamics”?
(3) Describe the three mechanisms of “heat transfer”.
(4) How many joules, how many calaories, does it take to raise the temperature if one kilogram of aluminum by 5oC?
(5) What is a “phase transition”? How much energy must I add to 1 kg of water at 95oC to turn it into steam?
(6) What is the relation between “statistics” and “times arrow”? What is the relation between evaporation, Brownian motion, smelling your friend’s perfume, and “Maxwell-Boltzman statistics”?

Friday, October 8, 1999

(1) Although hydrogen is the most prevalent element in the universe, very little of it is found in the earth’s atmosphere. Why?
(2) Give several equivalent statements of the “second law of thermodynamics”.
(3) What is “entropy”? Give examples of its “natural” increase, decrease.
(4) What happens to the entropy of heliun when natural gas is burned?
(5) What is a “Carnot efficiency”? Why is the concept practically important?
(6) What is the difference between a “heat engine”, a refrigerator, and a “heat pump”?

Monday, October 11, 1999

(1) Why is the “maximum thermodynamic efficiency” for the PWR higher than that for the BWR?
(2) Why does cold water contain more disolved gas than the same amount of hot water?
(3) What’s so bad about having a lot of “waste heat”?
(4) Why are “dry towers” less thermally efficient than “wet towers”?
(5) How and why is water used for the production of energy for human beings?
(6) Roughly how muich rain does the Detroit area receive each year?
(7) How does electric power production lead to “social pollution”?
(8) What criteria should be considered in defining the “efficiency” of an energy production facility?
(9)  What is an “aquifer”, why is it important, and how are they commonly damaged?

Friday, October 15, 1999

(1) What does magnatism have to do with the verification of the theory of plate tectonics ?
(2) How, and why, is birthrate related to the import of mineral resources?
(3) Why does “the power of exponential growth often” elude “human understanding”?
(4) Suppose that mineral use increased exponentially rather than linearly, as assumed in Table 10.1. Would the lifetimes given in that table increase, decrease, or remain the same? Why?
(5) If energy supplies were infinite,all resources would be inexhaustible. True of false? Why?
(6) What is the relation between a materials abundance and its reserves?
(7) What does resource availability have to do with international peace?
(8) Why is it difficult to estimate reserves, resources?

Monday, October 18, 1999

(1) Does the energy growth rate coincide with the rate of growth of the economy?
(2) Is the U.S. annual production of petroleum still rising?
(3) Is the price you pay at the gasoline pump high, low, or unchanged, compred to historical prices?  Does the price that you pay include all of the costs of getting the gasoline to you?
(4) What is the Hubbert Method of estimating total fuel resources?  What’s wrong with it? What are the alternatives?
(5) If we double the amount of petroleum reserves, do we double the time until they are exhausted?
(6) Who is opposed to the Strategic Petroleum Reserve and why ?
(7) What are the advantages and disadvantages of oil shale? Tar sands/
(8) What is the relation between fuel gas supplies and coal supplies?
(9) What are the relative advantages and disadvantages of strip and deap coal mining? Coal is cheap; why is it relatively unused? What should we do about this relative disuse?

Wednesday, October 20, 1999

 (1) How does your average fuel consumption compare with Fig.12.1? Where does your driving fit in Fig.12.2b? in Fig. 12.11?  How much does your car cost you per year? Assuming your cart meets Federal standards for 1998, how much pollution do you produce by commuting to school?   What kind of vehicle do you use?  What is your usual “load factor”? How does your efficiency compare with that of a Boing 777?
(2) How and why does automobile pollution control influence automobile efficiency and cost?
(3) What would it take to get you to commute via “mass transit”?  Which would be more preferable,bus or train? why?  Why is mass transit more prevalent in Europe than here?
(4) Why, or why not, are tail pipe measurements a good way to control air pollution? Are there alternatives?
(5) Does carbon monoxide have anything to do with “highway madness”? Why?
(6) Why has California been a pace setter for automotive pollution control? Results?
(7) Why not change from a gasoline to an ethanol economy?

Monday, October 25, 1999

 (1) How does city weather differ from country weather? Why? Is the difference “good” or “bad”?  (Can local air be lethal?)  What can be done about it?  Is the effort worth it?
(2) How do we know that the atmosphere does not have constant density?
(3) Do you weigh more or less than the weight of the pollutants you contribute annually to your local atmosphere?
(4) What is the difference between gaseous and particulate pollutants?  What methods are used to reduce each?  What are problems are associated with these methods?
(5) How can it be that ozone is good in some places, bad in others?  Which, if any, of these effects is increasing?  Why?
(6) How does pollution control hamper effects to increase fuel-use efficiency? How does local pollution sources and attempts at their control effect distant pollution levels?
(7) What is “acid rain”?  What causes it?  What are its effects?

Wednesday, October 27, 1999

 (1) What is the difference between “stratosphere” and “troposphere”?  Which is more stable; why?
(2) Why can’t you take weather forecasts, for periods longer than a week, very seriously?  What kind of weather prediction can you take seriously?
(3) What is the difference between “weather” and “climate”?
(4) Why are the equatorial regions hotter than the polar regions?  How does the ”surplus” energy get from one region to the other?
(5) What is the source of the decrease in entropy at the earth’s surface?
(6) How do we estimate previous climates?  Of what “practical” use are these estimates?
(7) What do volcanoes have to do with climate?  What does astronomy have to do with climate?

Friday, October 29, 1999

 (1) How can we know about previous climates?
(2) What is the “ocean conveyor”?  Why is it of interest in climate concerns?
(3) What is “albedo”?  Why is it important?  Is it subject to “anthropogenic change”?  Give some examples of this kind of change.
(4) What trace gases are in the atmosphere, how do they get there,  and what are their effects?
(5) What is the “atmospheric window”?  What is the “greenhouse effect”? Why are they important?
(6) What is a “feedback loop” and how does it effect climate?
(7) What are “general circulation models” and what are they good for?
(8) Is reforestation a “cure” or a delay of climate change problems?

Monday, November 1, 1999

(1) What is the difference between protons, neutrons, and nucleons?
(2) Why does N increase faster than Z in stable nuclei?
(3) Why does the binding energy per nucleon of light nuclei increase with increasing A? Why does the binding energy per nucleon of heavy nuclei decrease with increasing A?
(4) What is “radioactive half life”?  What particles are released in radioactive decay?
(5) What is the difference between nuclear fission and nuclear fusion?  How come energy can be released in either?

Wednesday, November 3, 1999

(1) What is the difference between  “fissile” and “fertile” nuclei?  Why, and how, must uranium be “enriched”?
(2) What is the difference between “prompt” and “delayed”, between “slow” and “fast”, neutrons?
(3) What is the difference between “moderators’ and “control rods”?  Why are they necessary?
(4) What is the difference between “conventional” and “breeder” reactors?
(5) Do we have “fusion energy” yet on earth?  What are the difficulties in the way of making it more prevalent?  How are we going about trying to overcome these difficulties?

Friday, November 5, 1999

(1) What is a nuclear “catastrophic accident”?  Does it describe Three Mile Island or Chernobyl? Why or why not? What did happen at Three Mile Island and Chernobyl? What were the similarities and differences between these two events?
(2) What is the difference between “event trees” and “fault trees”?
(3) What were the main conclusions of the Rasmussen report?  What was wrong with it?
(4) What are the differences between “roentgen”, “rad”, and “rem”, “gray”, “sievert”?
(5) What is “linear dose theory” and how is it used?  What is wrong with it?
(6) Compare the efforts and effects for disposing of “ashes” from nuclear power generation with those from fossil fuel power.

Monday, November 8, 1999

(1) What is the difference between “ionizing” and “non-ionizing” radiation?  What are their biological effects?
(2) What kind of wastes are produced by a “properly functioning” nuclear energy program? By a similar fossil fuel program?  What are their effects upon the environment?  How do we plan to handle them?  How well do our actions correspond with our plans?
(3) How would you compare the overall health and environmental effects of fossil and nuclear power programs, in the near and far future?   Which would you prefer?  How does the piblic feel?
(4) Are there radiation hazards to the public other than from nuclear power programs?  What, if anything, is being done about them?  Are you concerned or active about them?
(5) Is the public, are you, as concerned with nuclear weapon programs as with nuclear power possibilities?  Can you have one withjout the other?

Wednesday, November 10, 1999

NOTE TO STUDENTS: I am writing to you this way because I don’t have all of your e-mail addresses and I want this note to reach you all.
I have been very disappointed in the large amount of absenteeism in this course and the lack of effective class participation.  I presume that this apparent lack of interest on your part is an indicator of your disappointment with the class/course.  Rather than just having the class drift to an unsatisfactory conclusion, I hope that , with your help, it can be changed so as to reach out effectively to more of you.  Please see me individually, in my office or after class (on Wed. or Fri.) so that I can get some insight into the source of your apparent dissatisfaction and so that we can generate ideas to improve things for the rest of the semester.   Thanks - A.M.S.

(1) Describe some of the differences between acoustic and electromagnetic waves.
(2) What parts of the human body respond to: infrared radiation, ultraviolet  radiation, X-rays?
(3) Given that it is so difficult for mankind to produce “controlled nuclear fusion” here on earth, how come it is the source of the sun’s awesome power production? How does this energy reach the earth?
(4) What is the ratio of the energy received by the earth from the sun to the energy radiated by the earth to outer space?  What is the ratio of the energy emitted per unit area of the sun to that emitted per unit area of the earth?
(5) What are the advantages, disadvantages, of wind energy? What is its potential?
(6)  What has “marginal cost” got to do with the development of wind power? Regulatory power?

Friday, November 12, 1999

(1)  What is the difference between “solar cell” electric power production and the “Large-Scale Solar energy Projects” discussed at the end of chapter 19? What are the advantages and disadvantages of each?
(2) What is “load shifting”, why is it important, and what is its connection with “thermal storage”?  What other forms of energy storage are practical?
(3) What are the differences between “conductors”, “insulators”, and “semi-conductors”?
(4) What is the difference between “crystalline” and “amorphous” semiconductor solar cells?  What are the advantages and disadvantages of each ?
(5)  What are the different types of “solar farms”?
(6)  What are the relative advantages and disadvantages of “solar farms” as compared to “wind farms”?

Monday, November 15, 1999

(1)  How is water power related to solar energy?  to wind power?
(2)  Why can’t a vertical-axis water wheel be placed in the middle of a stream? What are the advantages and disadvantages of the various horizontal-axis water wheels as compared to vertical-axis ones?
(3)  What are some of the positive and negative consequences of dam construction? What are we doing in the U.S. to deal with them?  What is the difference between “low-head” and other dams?
(4)  What is the relation between “base load” and “pumped storage”?
(5)  Give and discuss (advantages and disadvantages) and example of “moon power”.  How does it depend upon “resonance”?
(6)  What are some of the effects, positive and negative, of OTEC?
(7)  What are some other means of obtaining power from the earth’s waters?

Wednesday, November 17, 1999

(1)  How has photosynthesis changed the earth?  Why is it necessary for animal life?
(2)  Why is chlorophyll green? What determines the efficiency of photosynthesis?
(3)  If solar cells are more efficient than plants, why not give up reliance on the latter?
(4)  How can a cow contribute to societal energy needs?
(5)  Why can’t we rely upon corn production to meet our automotive fuel needs whereas it may very well meet our requirements for chemical feedstocks?

Friday, November 19, 1999

(1) What did people do before farming?  What changes did farming produce in human society?
(2)  What is “swiden agriculture”?  Why is it not possible in high population density areas or in “conspicuous consumption” societies?  How many people could it support if they could live without eating any meat?  Compare the labor input to swiden agriculture with that of 1979 US farming. Is the following True or false?: In swiden agriculture, people “eat contemporary sunlight” whereas in the US they “eat ancient sunlight”. Explain!
(3)  What were the three revolutions in American agriculture? What are their effects, good and bad?
(4)  Which American crop has shown the least increase in agricultural productivity, 1935-79?
(5)  What are the advantages and disadvantages of meat production? feedlot meat production?
(6) Which is more efficient: “organic farming” or regular commercial farming?
(7) Why be concerned with stability rather than productivity in agriculture?

Monday, November 29, 1999

(1) Why is it advantageous to smooth out the demand for electrical energy?  How is this achieved by “load mangement”?  How does “load mangement” differ from pumped storage”?
(2) What is the difference between “conventional” superconductors and the recently discovered “high temperature superconductors”?  Why are the latter more “interesting” from a practical point of view?
(3) What is “wheeling”?  Why is it important?
(4) What is “maglev”?  How is it related to superconductivity?
(5) Why store energy?  What is a “flywheel battery”? a “phase change battery”?  How do they differ from an “ordinary battery”?  Why are any of these batteries important?

Wednesday, December 1, 1999

(1) What is the energy source for geothermal plants”? Why aren’t they uniformly distributed over the earth’s surface?  What are their advantages and disadvantages?
(2)  How can garbage be made “useful”?  Why is it not done more often in the U.S.?
(3) Where and how is separation of recyclables most efficiently done?
(4) What are the advantages and disadvantages of using hydrogen for automobile fuel?
(5) What are the arguments, for and against,  replacing our national electricity system by a hydrogen distribution system?

Friday, December 1, 1999

(1) What is the difference between the “conservation of energy” and “energy conservation”? Which is “optional”? How do people feel about each?  Which may save money?
(2) Why is there often a conflict of interest between the manufacturer and the user of an energy-using device (home, car, appliance,...)?
(3  What do you do to conserve energy in lighting?  What could you do?  Why don’t you?
(4) What is “demand side management” and why is it advantageous to public utilities?
(5) How could you reduce heat loss or gain in your home?  Should you?
(6) Why do consumers denabd shorter payback times than do government and industry?
(7) How can the sun contribute to the heating of your home? to the university?
Monday, December 6, 1999

(1) From the point of view of energy conservation, what are the advantages of multiple dwellings over single family homes?
(2)  Compare electric baseboard heating, gas furnace heating, and heat pumps, from the point of view of energy efficiency.
(3  What are the advantages of demand water heaters as compared to standard Amersican reservoir water heaters?
(4)  What are the advantages of “rolladen”?
(5  What is “life-cycle costing” and what are its advantages, disadvantages?
(6)  Why is it that large buildings, but nor small ones, have to be cooled all year round?

Wednesday, December 8, 1999

(1)  How does contemporary America’s “garbage habits” compare with those of other countries and with itself in the past?  Explain the changes.  Ditto for our “energy habits”.
(2)  Compare the recent growth rate of energy use in American industry with that of the rest of our society. Why the difference?
(3)  What is the difference between the meaning of the terms “reduce”, “reuse”, and “recycle” ?  Does the U.S. react  differently than other counties to these terms?  Why?
(4) Why do you think “that the poor do not recycle at rates anywhere near the better-offs”(p.596)?
(5)  What are the reasons for recycling aluminum and steel?  Why is a higher fraction of steel than aluminum recycled?
(6)  Does it “pay” to recycle glass?  If not, why do so?

Friday, December 10, 1999

(1)  Why is there a market for recycled “unmixed” paper but little or none for “mixed” paper?
(2)  What are the arguments for and against the recycling of paper?
(3)  What are the arguments for and against the recycling of plastics?
(4)  How does the entropy concept relate to recycling?
(5) What are the arguments for and against curbside recycling?
(6)  Why is the cost of landfills increasing?  What are the alternatives?
(7)  Do “bottle bills” imply reuse or recycling?
(8)  Why does a single use of a “returnable” bottle require the loss of more energy than that for a “throwaway”?

Monday, December 13, 1999
(0)  What century do you live in?
(1)  In what way is ours a “human-made world”?.
(2)  In what way does complexity guarantee the stability of a system?  In what way does it hinder stability?
(3)  What are the causes and consequences of lost topsoil?  How do loss of forests contribute to loss of land?  What is the role of the goat?
(4) What is the role of “immigrant” plants and animals?
(5)  What is the role of a limited variety of food plants and animals?
(6)  What is the “Superfund” and what are its implications?  How “clean” should the Jefferson Ave. Uniroyal Tire site (at the Belle Isle Bridge) be made?
(7)  What are the factors which may determine whether or not people will accept risks?
(8)  What is the relation between “goal” and “method” in risk reduction?
(9)  How many “microrisks” are you willing to undergo for each of the activities in Table 26.1?  Is this an example of “cost-benefit” analysis?
(10) How much are you willing to spend per year for EPA regulations?  Do you follow these regulations when pertinent to your activities?  Do you know of any “pump handles” which should be removed?
(11)  What is the relation between economists and environmentalists?
(12)  What are the arguments for and against a “technological fix”? For an “emigration fix”?