1Reminders:• Read Article on Carbon Footprints (see web page link) for discussion in class on Wednesday.• Homework #9 due on Wednesday• Inquire/Inform #2 due November 19 (in class)• Research Project #2 topics selected today, due December 8• Reading Chapter 9Research Topics #2 – due Monday December 8, 2008.You are asked by the Department of Energy to critically investigate a particular issue of importance for the new administration. You have been asked to write a four page brief on the following topic. You are asked to be concise and give enough information for the Department to digest the information and follow up with more detailed references.Details are linked from the classWeb page. Read them carefully.If you have a preference for a different topic, please make arrangements to meet with me and discuss the alternate topic proposal. This is encouraged. Deadline for topic changes is Friday, November 21, 2008.Research Project Reminders…1. You must include two (2) calculations of relevance in a separate Appendix and refer to them in the text.Check your calculations to see if they make senseFeel free to come and talk to me about the calculationsExample: “Switching to solar water heaters could save the people of Boulder a hundred trillion dollars ($100,000,000,000) in natural gas costs. – see calculation 1 in Appendix.”What is incorrect or needs clarification in this sentence?i) Any energy amount or fuel quantity or dollar figure needs to say over what period of time. Is this for one year?ii) $100,000,000,000 is one hundred billion (not trillion).iii) Does the result seem reasonable? Boulder Pop ~ 100,000, so that would be saving $1000 per person or $1,000,000 per person? Both sound high…. Why?Example:“Advantages and Disadvantages of Wind Energy”, April 5, 2007 by Roy D’Silva, http://www.buzzle/com/articles/advantages-disadvantages-wind-energy.html“Buzzle.com is a website dedicated to ‘intelligent life on the web.’ They have different authors’ remarks about certain issues that pertain to current issues.”2. You must include at least six (6) references. At least twomust be in peer-reviewed journals. You must include 2-4 sentences on each reference detailing what the resource is (not what the content of the article is).Does the above quote tell you the reliability of the source? No.Perhaps I would not quote this source to the Department of Energy. However, if this article points to other references, one can always check them out.2“Example case of Brandy Bridges of Ellsworth Maine – was a cleanup cost of $2004.28 for a broken bulb, which doesn’t include the cost of frayed nerves and risks to health.”“The United States Environmental Agency states that the 5 mg of mercury in fluorescent bulbs is a hundred times less than is found in an old style glass thermometer. If you should happen to break a bulb, mercury will be released, and care should be taken, but cleanup is not overly dangerous.”Air PollutionWhat is a thermal inversion?Air pollution has local, regional and global impacts.What is smog?Los AngelesMexico CityWhat exactly happens to the “smoke”coming out of a “smoke stack”?Area= AFWe need some Air PhysicsPressure = Force / Area (for example pounds/ inch2)If equal conditions in the air on each side, then the net force on the middle piece is zero (equilibrium) and no net acceleration or motion.FFFF F3F FFFF FAdditional Forces1. Gravity – downwards2. Buoyancy force – upwardsDue to the weight of all the air above the, the air pressure is larger lower down near the earth and the air pressure is smaller higher up in the atmosphere. Notice the lower pressure in Boulder than at sea level! Thus, there is also a buoyancy force upwards.GravityBuoyancyArchimedes’ PrincipleForce upwards = (Density of water x Volume of object) x g Total Pressure in a LiquidPressure = 0 at topPressure increaseslinearly with depthAll slices are the same density even though at higher pressure since water is not easily compressed.Thus the buoyancy force upwards does not depend on the depth!Total weight of columnSCUBA DivingWhen SCUBA diving they add just the right amount of weight so that the gravity force down balances the buoyancy force up.If too much weight, you would just keep sinking down to the bottom (assuming you do not paddle).If too little weight, you would just keep rising up to the top (again, assuming you do not paddle).Clicker QuestionIf you are diving deep underwater, and the buoyancy force is greater than the gravitational force, you will?A) You will sink to the bottom.B) You will rise to the surface.C) You will rise to some level below the surface and stay there.D) You will sink to some level above the bottom and stay there.E) A shark will eat you first.The buoyancy force in water is rather independent of depth since the density is the water is almost constant.Gases are DifferentPressure = 0 at topGas is compressedDensity increases with depth!←Highest density←Lowest densityUnlike water, gases compress under higher pressure (thus higher density). Therefore buoyancy force is larger near the earth and gets smaller higher in the atmosphere !Pressure increaseslinearly with depth4Hot Gas near the GroundHot gas density is less than surrounding cooler air– Buoyant force upward greater than weight downward– Thus hot gas risesGas expands as it rises and cools as it expands- Thus the Buoyant force is reducedRises until buoyant force equals weight-Then is stays at this height- When does this happen?Adiabatic Lapse Rate (ALR)Going up:Pressure decreasesGas bubble expandsTemperature decreasesAbout -9.3 0C / kilometerGaseous object containing water vapor is more complicated (water vapor may condense). Net effect is to reduce the lapse rate to about half the value aboveIn the Troposphere (up to ~ 10,000 meters), the temperature drops with altitude.It drops about 3 degrees Fahrenheit per 1000 feet.Temperature →Altitude →Hot gas blobAtmosphereIf gas blob is always hotter than atmosphere are all altitudes, it always has a buoyancy force larger than gravity and keeps rising to the upper atmosphere.Good thing for avoiding local pollution. Note that global issues are still a problem even in this case, but now better distributed.Temperature →Altitude →Hot gas blobAtmosphereGas blob gets cooler thansurroundingsHot gas blob rises due to a larger buoyancy force upward until it reaches the “crossing point” and then it
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