Midterm Review Sheet Version 2.0 Physics 1110: Energy on This World and Elsewhere November 20, 2013 What, where and when The midterm will be in

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1 Midterm Review Sheet Version 2.0 What, where and when The midterm will be in class, Thursday, on November 21. There will be 30 multiplechoice questions. It will be closed book and closed notes, but you are allowed hand-written notes on one sheet of paper. Review Materials Class notes: Chapters 1 4. Lecture slides, #1 through #20, but not including nuclear power. Chapters 3 and 5 from Feynman s The Character of Physical Law. Chapter 1 of Muller s Technology and Physics for Future Presidents. Isaac Asimov s The Last Question. Muller s Energy for Future Presidents: preface, intro and chapters Richter s Smoke and Mirrors: Chapters Solutions for homeworks #2 and #3. General Comments Less than half the questions will require any type of calculation. Many of those that do require a calculation will be quite close to problems you have seen in the homework. Don t forget your calculator, and remember you are allowed notes that fill one side of one sheet of paper, but they must be hand written. Review Strategy I will expect that you have done the reading. With that said, I will not be looking to pick out obscure details from the readings on which to test you. If you feel that something has not been discussed in lecture, does not appear in the chapters of the class notes that have been assigned, and has not come up in the homework, you are at least relatively safe. Also, I don t expect you to remember lots and lots of numbers. If I ask you how much land area is needed to produce all of our electricity using solar panels, it would be fair if I ask if the land area is closest to that of a) Alaska, b) California, c) Texas or d) Massachusetts? You do not need to know the exact number of square miles! However, look carefully at the Important Concepts below. In several places I give you a rather explicit heads up that I am going to ask about certain details. These are appropriate things to include in your hand-written notes. Important Concepts as of the first quiz Below is the selection of important concepts that were given on the review sheet for the first quiz. These are fair game for the midterm, although somewhat more emphasis will be given to later material. See below for the section on important concepts that go beyond those covered by the quiz. You should understand what primary energy sources are, and be able to give examples. You should understand what end uses of energy are, and be aware of some of the ways in which end uses are categorized. You should understand the concept of an energy grid, and be able to give at least two examples.

2 Important Concepts as of the first quiz continued Conservation of energy * Balls rolling on hills, and the movement of energy between potential energy and kinetic energy. * Know that gravitational potential energy is equal to mgh. * Know that kinetic energy is equal to 1 2 mv2. * Know that work is equal to F d. * You should understand that when you do work on something, the energy must go somewhere. For example, if I do work pushing a bowling ball, that work is turned into kinetic energy. Similarly, if an object is sliding to a stop, frictional forces are doing work on the object, causing it to lose its kinetic energy. * Work performed by frictional forces. m Big m Small * Levers and seesaws, and the law of levers: = l Long l Short. Recognizing units * You should be able to recognize the various units we have used for energy, including joules, kwhrs, BTU s and calories. You do NOT need to know conversion factors. * You should be able to recognize the various units we have used for power, including the Watt, the kilowatt (kw), BTU s per hour. You do NOT need to know conversion factors. * You should know the various Standard International Units that we have discussed for length (the meter), time (the second), power (the watt), energy (the joule), velocity (m/s). Units were discussed in some of the earlier lectures. * I will assume that you know prefixes such as kilo (k, 10 3 ), mega (M, 10 6 ), and giga (G, 10 9 ). Power and Energy: you should understand the difference between power and energy. * You should understand that if you need to compute the power something has produced or consumed, you need to use the equation P = energy/time. * You should understand that if you need to compute the energy something has produced or consumed, you need to use the equation Energy = power time. Gases doing work. * The concept of pressure. * You should recognize ideal gas law, and understand that it provides a way to calculate how gases expand when heat is added to them.

3 Important Concepts as of the first quiz continued Heat engines. * Be familiar with the general concept of a heat engine, and understand what the quantities Q C, Q H, T C, T H and W refer to. * Know examples of heat engines including internal combustion engines, external combustion engines, and heat engines that utilize outside sources of heat (such as solar thermal) that do not use combustion directly (although one could argue that solar thermal is using external combustion, but the source, our Sun, is just far way!). * You should know that, for a heat engine, Efficiency = W Q H =1 Q C Q H,andalso that Maximum Efficiency = ε Carnot =1 T C T H. The first law of thermodynamics. * The concept of the internal energy of a gas. * The idea that the first law of thermodynamics is essentially an expression of the conservation of energy. Entropy * What is entropy? * The second law of thermodynamics and its implications for changes in entropy. * Be familiar with some of the examples and/or metaphors we have discussed that involve the second law of thermodynamics, or equivalently, Feynman s principle of irreversibility. Important Concepts AFTER the first quiz Fossil Fuels * Know the concepts of reserves and resources and the differences between them. * Familiarize yourself with the (overly simplified) time scales associated with exhausting supplies of fossil fuels. In particular, look at the some of the tables provided in lecture 11. If you open up the pdf, you might look at pages 13 and 14 (domestic and world). Note, the 400+ years worth of coal indicated on page 13 is roughly a factor of two bigger than what you computed in your homework because I treated all resources equally, that is, I did not exclude coal resources that were estimated to not be recoverable by today s standards. * Remind yourself of our discussions of non-conventional oil, including bitumen from tar sands, kerogen from oil shale, and light tight oil (LTO) that is trapped in shale formations and is recovered using fracking and horizontal drilling. Be familiar with the general size of the deposits (I m not sure I gave a good number for LTO), and some of the issues concerning their extraction. * Natural gas. Be familiar with the recent evolution of natural gas reserves (in the U.S.) and the importance of the Marcellus Shale. See slides in lecture 14. * Which five countries have the most coal, and in what order? See lecture 13.

4 Important Concepts AFTER the first quiz - continued Climate change * Know the CO 2 concentration in the atmosphere both now and before the industrial revolution. Muller gives 280 parts per million (ppm) as the pre-industrialrevolution number. I believe that Richter gives 270 ppm. These numbers are, because of their historical nature, tough to pin down, so a small difference is to be expected depending on the data one uses. Muller states that it has gone up by 40%, which using 280 ppm as a starting point, implies 392 ppm, which indeed is right around the most recent numbers you see quoted. * Have a general sense of the temperature history of the world as described in, for example, Figure 4.4 of Richter s book. * Have a basic (non-quantitative) understanding of what the greenhouse effect. * Know the major greenhouse gases. * Know examples of proxy measures of global temperatures. * Know in rough terms what is meant by positive feedback systems and negative feedback systems. For example, which is the Iris Effect is. Renewables in general * What are some of the more important sources of renewable energy, and how large are these resources compared to the total human use of primary energy. You should be familiar with Table 8.1 on page 66 of Richter s book. * What are the largest sources of renewable energy in the U.S., and what are their relative sizes? (See, for example, page 23 of lecture 16.) Biofuels * Ethanol is well on the way toward making up 10% by volume of the gasoline sold in the US. What would be the impact on agriculture if we used the current approaches and tried for something closer to 100%? * The wisdom of using ethanol as a gasoline substitute is the subject of considerable debate. What are some of the pros and cons of using ethanol? * Be aware of the potential benefits of algae, and also the fact that algae is not yet a significant contributing factor to biodiesel production. Wind * Which five countries get the largest fraction of their electricity from wind? (Here you might look at page 26 of lecture 18.) * Know the equation P = 1 2 Aρ v3 and how to use it. * Know what a PTC is.

5 Review Sheet for Midterm continued Physics 1110: Energy on This World and Elsewhere November 20, 2011 Important Concepts continued Solar energy * Know the difference between solar thermal and photovoltaics. * Know the equations P = efficiency area intensity, and similarly Area = P/(efficiency intensity), and how to use them. (These equations are discussed during both lectures 19 and 20.) * Have a semi-quantitative understanding of the amount of land needed to produce all of our electricity from solar farms. (See, for example, lecture 20.) * Other than cost, what are some of the issues that restrict the use of solar energy? Are there any varieties of solar thermal that store (thermal) energy for use at night? (Yes, the power-tower design.)

Physics Energy On This World and Elsewhere - Fall 2013 Problem Set #2 with solutions

Physics Energy On This World and Elsewhere - Fall 2013 Problem Set #2 with solutions Problem Set #2 with solutions When doing unit conversions, for full credit, you must explicitly show how units cancel. Also, you may need to look up certain equivalence relations on the internet. Show