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Solved: Can the combined turbine-generator efficiency be

Thermodynamics: An Engineering Approach | 8th Edition | ISBN: 9780073398174 | Authors: Yunus A. Cengel ISBN: 9780073398174 171

Solution for problem 255C Chapter 2

Thermodynamics: An Engineering Approach | 8th Edition

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Thermodynamics: An Engineering Approach | 8th Edition | ISBN: 9780073398174 | Authors: Yunus A. Cengel

Thermodynamics: An Engineering Approach | 8th Edition

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2
Problem 255C

Can the combined turbine-generator efficiency be greater than either the turbine efficiency or the generator efficiency? Explain.

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EXAM 2 STUDY GUIDE Evolution ­ Change over time in a populations genetic makeup (gene pool) through successive generations ­ natural selection occurs to individuals best suited for current conditions (survival of the fittest) ­ evolution takes place after successive populations ­ -Mechanisms of evolution are mutations and natural selection acting on individuals with genetic material Define and explain the process of Evolution. ­ Genetics passed on to future generations ­ “descent with modification” ­ Adaptations­ any trait that provides advantage to its possessor ­ Population change  genetics  changed genes passed on to future generations Co­evolution ­Process whereby the evolution of one organism drives the evolution of another monarch ­ Caterpillars feed on milkweed ­ Milkweed developed hairs on leaves, poisons monarch develops ability to breakdown poison ­milkweed produces thicker substance, deterring feeding monarch chews stem to drain the substance Clearly describe the relationship between Genetics and the processes of Natural Selection and Evolution ­ organisms best fit under the current conditions survive and produce more offspring (natural selection) ­ best fit = genetic material that gives organisms an advantage over others in population ­ current environment determines whether a mutation is harmful or beneficial to the organism ­ natural selection acts upon genetic variation in populations­ natural selection can only act upon pre­existing variation ­ ex: sickle cell anemia kills, but also creates resistance to malaria Clearly describe what is meant by the Selfish Gene Theory and identify and describe examples of ecological phenomenon that either support or refute this theory. ­ Selfish gene theory states that an organism will do what it takes to live and reproduce offspring so they can pass on their genes ­ Everything we do is driven by subconscious urge to reproduce ­ Ex: genes reproducing at expense of the organism­ genes of male spiders' instinctive mating behavior increase the fitness by allowing it to reproduce, but shorten its life by exposing it to the risk of being eaten by the cannibalistic female Gene pool ­ Complete set of all genes in the individuals of a given population and species ­ Functions of genes­ code for our traits ­ Mutations are random changes in the structure of number of DNA molecules in a cell­ most are lethal ­ It can be beneficial­ introduce how a gene enters into a population if successful Speciation ­ Collection of genetic mutations changing that lead to populations becoming reproductively isolated (no longer being able to reproduce in nature) Evolutionary selection ­ Natural selection: major driving force of evolution ­ Acts upon genetic variation in populations Sexual selection ­ Mate choice­ maximize reproductive potential (for peacocks­ strength, territory, ornaments) Directional selection ­ Extreme trait is favored over other, that extreme trait becomes more prevalent in population (long tailed bird, longer the tail the more likely to get a mate­ longer tailed birds mate and reproduce) Stabilizing selection ­ No benefit for either extremes (birds having 5 babies­ too many will be too hard to take care of, too few will die and offspring is low) Diversifying selection ­ Both extremes are favored­ leads to speciation (new species being evolved) Evidence of Ecology ­ Investigations of how organisms interact with biotic (living) and abiotic (non­living) factors ­ Range of tolerance: for all abiotic factors in an environment, an organism can tolerate it­ if it goes out of range, death occurs ­ Ex: weather (abiotic)­ fish population (biotic) decreases when water temperature increases ­ Producers: green plants, photosynthesis, autotrophs ­ Consumers: heterotrophs, primary: herbivores/ secondary: carnivores and omnivores ­ Two key metabolic processes: 1. Photosynthesis ­ Takes in carbon dioxide/sunlight ­ Produces/releases sugar, oxygen 2. Respiration ­ Takes place in sugar and oxygen ­ Produces sugar and heat Law of thermodynamics st ­ 1 ndaw: energy can be neither created nor destroyed­ it can only be converted ­ 2 law: no energy conversion is 100% efficient­ always a net loss of usable energy Energy flow in ecosystem ­ Producers  primary consumers  secondary consumers tertiary consumer Pyramid of biomass nd ­ 10% of bottom energy in the triangle to be transferred into next level (2 law­ no energy conversion is 100% efficient) Biogeochemical cycle 1. Water cycle: evaporation  condensation  precipitation ­ Transpiration: water is lost through plants leaves and goes into atmosphere 2. Nitrogen cycle: macro nutrient/ amino acid/protein ­ 78% of atmosphere is nitrogen but most isn’t in form that plants can have 3 ways nitrogen becomes available to plants (fixation) Atmospheric nitrogen fixation (lightening breaks nitrogen which dissolves in rain, then plants get it) Biological fixation (beans have bacteria in it that grab onto atmospheric nitrogen) Industrial nitrogen fixation (high pressure and heat combines n and h into ammonia) 3. Phosphorus cycle: macro nutrient/ essential for DNA ­ No atmospheric stage, erosion allows it to break up­ found in sedimentary rock 4 . Carbon­oxygen cycle ­ Photosynthesis and respiration ­ Carbon dioxide draws out for respiration, oxygen draws in ­ Burning of fossil fuels changes balance Oceanic importance in carbon cycling ­ Coral reef acts as natural carbon sink ­ Co2 naturally dissolves in ocean water Climate and biomes Hydraulic cycle ­ Biogeography: study of where organisms exist ­ Biodiversity: variations of organisms in an environment­ diversity within species is beneficial Factors impacting biodiversity: ­ Nutrient rich, abundant water, stable environment (organisms become adapted to same temp, easier for them to stay alive) ­ Two major factors driving climate: 1. Temperature 2. Moisture ­ Milkankovitch cycles impact solar radiation on earth’s surface, these cycles drive ice ages Greenhouse effect ­ Warms earth ­ Light energy in small wavelengths hit surface of planet  waves change from light to long infrared (heat) and is trapped in planet’s atmosphere Albedo effect ­ Reflection of solar radiation (wavelength strikes white snow, reflects off into space, and prevents additional warming Global wind patterns ­ Winds blow west to east by Michigan  ­ east to west by equator  Water ­ high specific heat capacity­ takes lots of energy to warm up ­ results in both global and local factors that impact climate proximity to ocean currents: ­ cold ocean currents offshore result in more stable conditions (drier climate) ­ warm ocean currents offshore result in less stable conditions (wetter climate) ­ as altitude rises, temperature goes down Rain shadow effect (orographic) ­ moisture in air hits mountain (windward side), moisture and air move up and gets colder (as alt. rises, temp goes down), condensation turns to rain and it gets lost and stuck on mountain top, air keeps going over (leeward side) and temps increase ­ this process drives moisture distribution over USA ­ because of this effect, trees will die on leeward side and grasslands will pop up instead Lake effect ­ can absorb and hold large quantities of heat and impacts rate at which temperatures on land shift, associated with changing seasons ­ impacts precipitation levels ­ lake effect snow­ lake water is warm and water evaporates in cold climate, which in turn produces more snow Atmospheric and soil moisture ­ wet climates hold in heat overnight (think of a rainforest­ the temps are pretty even day and night) because of waters high specific heat index ­ dry climates have little to no moisture­ nothing to hold in heat all day (think of dry dessert, hot in the day but freezing at night) General species ­ Niche: an organism's role in an ecosystem­ includes environment organism lives in, and the organism's job in that environment­ also encompass what it eats, how it interacts with other living things or biotic factors, and also how it interacts with the non­living, or abiotic, parts of the environment as well ­ native species: organisms you’d expect to see in an ecosystem ­ non­native/exotic species: intentionally/unintentionally introduced, can be good or bad depending on the area or species­ successful invaders tend to have larger niches ­ invasive species: when non­natives become problematic­ the characteristics are: 1. small size 2. high biotic potential 3. large niche 4. no predators How species interact ­ predator and prey relationship ­ competition: 1. intraspecific­ within same species 2. interspecific­ between different species (niche overlap can occur) ­ Gause’s principle ­ No two different species can occupy identical niche for any significant amount of time­ there are 3 outcomes: 1. Extinction of one of the species 2. Competitive exclusion (1 species is forced out) 3. Character displacement (trait modification occurs) Population dynamics­ major factors influencing ­ Carrying capacity: (K) the number of organisms expected to sustain in an area ­ Biotic potential: (r ) rate the population grows under ideal conditions­ this always limits to population growth in nature­ environmental resistance: factors limiting growth (competition, resources, disease, climate) ­ Density dependent factors: varying effect on population based on population size­ disease and predation are density dependent meaning that pop. size helps determine the spread of disease ­ Density independent : same impact on population regardless of size of population­ weather or climate are usually independent of pop size Common insect outbreak cycle ­ Australian locust outbreak: food supply goes down  population dies out  food goes up  population goes up  repeat ­ ( r): more offspring, short lifespan, density dependent (think of insects) ­ (K): less offspring, longer lifespan, can be endangered species (think of elephant) Population growth ­ J shaped curve (r) – population graph shows pop growth passes the inflection point and crashes (refer to the Australian locust outbreak cycle above) ­ S shaped curve (K)­ population goes up, feels the environmental resistance, population size curves around the carrying capacity (inflection point) ­ Inflection point is the point at which a population goes up rapidly but rate of growth begins to slow

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Chapter 2, Problem 255C is Solved
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Textbook: Thermodynamics: An Engineering Approach
Edition: 8
Author: Yunus A. Cengel
ISBN: 9780073398174

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Solved: Can the combined turbine-generator efficiency be