Heat Conduction

Experiment 16: Heat conduction Introduction In this laboratory you will study heat flow across a temperature gradient. By comparing the temperature difference across one material to the temperature difference across a second material of known thermal conductivity, when both are conducting heat at a steady rate, you will be able to calculate the thermal conductivity of the first material. You will then compare the experimental value of the calculated thermal conductivity to the known value for that material.Thermal conductivity is an important concept in the earth sciences, with applications including estimating of cooling rates of magma chambers, geothermal explorations, and estimates of the age of the Earth. It is also important in regard to heat transport in air, to understanding the properties of insulating material (including the walls and windows of your house), and in many other areas. The objective of this laboratory experiment is to apply the concepts of heat flow to measure the thermal conductivity of various materials. Theory Temperature is a measure of the kinetic energy of the random motion of molecules with a material.As the temperature of a material increases, the random motion of its molecules increases, and the material absorbs and stores a quantity which we call heat. The material is said to be hotter. Heat, once thought to be a fundamental quantity specifically related to temperature, is now known to be simply another form of energy. The equivalence of heat and energy is one of the foundations of thermodynamics. As the molecules in one region of a material move, they collide with molecules in neighboring portions of the material, thus transferring some of their energy to other regions.The net result is that heat flows from regions with higher temperatures to regions with lower temperatures. An exact calculation of this heat flow can be very difficult for materials with complicated shapes and complicated temperature distributions, but in some s imple cases the heat flow can be calculated. In this experiment, we will consider the heat flow across a plate of material of cross sectional area A and thickness ? x when its faces are held at constant (and different) temperatures, as indicated in Fig. 1. Figure 1 Heat flow across a plate. In this case the rate of heat flow H across the material is given by H = KA !T ! x ( ) (1) where ! T = T2 † T1 is the temperature difference across the plate and K is a quantity called the thermal conductivity. Note that this equation only applies because we keep the top and bottom at fixed temperature. In a more general situation, the flow of heat would alter the temperature of the top and bottom, and a more complicated approach would be required to deal with the situation. Heat is transferred more efficiently through shapes with a large area that are subject to a large temperature difference, but more slowly through thicker materials.If the units of H are J/s, that of A are m2, ? x is in m, and the units of temperature are ? C or K, then the units of K must be W/m-oC. Prove this for yourself, and show it in your laboratory book. Since the Celsius degree is the same size as a degree on the Kelvin scale, the units of thermal conductivity are usually expressed as W/m-K. We will use Eq. (1) to measure the heat flow through a material of known thermal conductivity and then use this result to determine the thermal conductivity of unknown samples forced to conduct heat at the same rate.Thermocouples In order to apply Eq. (1) we will need to measure the temperature difference ? T across our samples. It would be difficult to insert a thermometer into the gap between plates without disrupting the heat flow, so we will instead use a temperature probe that uses a device known as a thermocouple. 2 Figure 2. A Thermocouple A thermocouple is simply two connected wires made of dissimilar metals. Whenever two different metals contact each other, a small voltage difference is generat ed. This voltage difference is dependent on the temperature of the junction.If we measure this voltage difference with an accurate voltmeter, we can look up the temperature of the junction relative to the temperature of the connection to the voltmeter in a thermocouple table. The instrument used in this lab does the conversion for you, so can read the temperature directly. The thermocouple probe is now a very common device for measuring temperature, particularly in small places. For, example many medical thermometers are now based on thermocouples rather than the more traditional liquid in a glass tube. Experiment: Apparatus:The apparatus for this experiment are shown in the following figure, which also demonstrates how you will use the equipment. Figure 3. The apparatus for measuring thermal conductivity. 3 The apparatus for this experiment consists of a hot plate to supply heat, an ice bath to absorb heat, and plates of various materials through which heat will follow. Temperature s of the plates will be measured with a glass thermometer. In addition, the diameter and thickness of each plate will be measured with vernier calipers. Method Measure the diameter and thickness of each plate provided.Calculate the areas of the plates. Create the following table in your report and fill it in. Table 1. Dimensions of various plates Material Masonite Aluminum Plexiglass Plywood Teflon Using the glass thermometer, measure the temperature of the room and ice bath. Record your values. I. Thermal Conductivity of Plexiglass Construct a â€Å"sandwich† consisting of aluminum, masonite and plexiglass with the slots arranged so that thermocouples can be inserted on either side of the masonite plate. Place the sandwich on the hot plate with the aluminum side down. Place the ice bath on top of the sandwich.Switch the hotplate controller on and set the Variac to approximately 40% power. The exact value is not important, but if the power is set much higher some of the mater ials may get too hot. WARNING: Use extreme caution around the hot plate and when handling any of the materials that come into contact with it for the remainder of the experiment. The surfaces will become HOT! It will take up to 30 minutes for the heat flow to achieve a steady state. Monitor the progress by plotting the temperature readings T1 of the thermocouple 1 and T2 of thermocouple 2 as a function of time. Expect a maximum time of 45 minutes.Take readings every 1 to 2 minutes. If you miss a reading, skip it and record the next reading at the appropriate time on your plot. 4 Diameter (cm) Diameter (m) Area (m2) Thickness (cm) Thickness (m) You should find that the temperature readings eventually approach constant values. Even if they are still drifting after 30 minutes, the small changes to the heat flow will have only a small effect on your results. Record final values of the temperatures for the aluminum/masonite/plexiglass sandwich. You now have all the data needed to calcula te the thermal conductivity of plexiglass.See the â€Å"analysis† section later in these notes for details about how to do this. Calculate its value. II. Thermal conductivity of Plywood Carefully remove the Plexiglas plate and replace it with the plywood sheet (with slot down). Reinsert thermocouple 2 and place the ice bath back on top of the sandwich. Since a steady state heat flow has already been established in the aluminum and masonite, this new configuration should take only about 20 minutes to achieve a steady state. While you are waiting for the temperature readings to stabilize, you may wish to use the time to calculate the thermal conductivity of Plexiglas.If you do this, keep an eye on the temperature readings so that you know when a steady state has been achieved. Record the steady state values of the temperature for the sandwich of aluminum/masonite/plywood. III. Thermal Conductivity of Teflon Carefully remove the plywood plate and replace it with the Teflon plate (with slot down). Reinsert thermocouple 2 and place the ice bath back on top of the sandwich. Again, a steady state will probably be achieved in about 20 minutes. Record the steady state values of the temperatures for the sandwich of aluminum/masonite/Teflon. Analysis If e neglect the heat that escapes from the edges of the plates (due to convection and radiation), all of the heat provided by the hot plate must flow through each of the plates and into the ice bath, once a steady state has been achieved. Thus the heat flow through each plate must be the same throughout the sandwich. In particular, this means that the heat flow through the masonite is equal to the heat flow through the top material. Therefore we can write Hm = Htop . Using Eq. (1) we find that K m Am ! Tm ! xm = K top Atop ! Ttop ! xtop ( ) ( ) (2) The thermal conductivity of masonite is known to be 0. 0476 W/mK.You can derive an expression from Eq. (1) for the thermal conductivity of the top plate. 5 Use your measur ed values and the known value for the Km to calculate the thermal conductivities of each of the top plates used. Prepare a table like that shown below and fill in the values in your report. Table 2. Thermal conductivities of materials used in this laboratory. Material Calculated thermal Published value of K conductivity (W/mK) (W/mK) Aluminum Masonite Plexiglass Plywood Teflon The least accurate measurements in this experiment are the thermocouple voltages, which are only measured to 0. 1 mV accuracy.Based on this accuracy, estimate the uncertainty in the temperature difference across the masonite plate. Considering the uncertainty in this temperature difference only, what is the approximate percentage error in your calculated thermal conductivity values? Questions: 1. Use Eq. (1) to calculate the total rate of heat flow H through each of the plates in Part 1. (Note: The same value of H must hold for each plate, so you only need to use Eq. (1) once). 2. Do your results agree with th e expected values? If not, what measurements, processes, and/or assumptions do you suspect to have been significant sources of error? 6

Most Significant Events of Each Decade

Most Significant Events Final Project K A University of Phoenix: Axia College Jonathan Tietz November 28, 2010 Most Significant Events of the 50`s, 60`s 70`s 80`s and 90`s World War II lasted from 1939 to 1945. This was a war that involved most of the world’s nations and all of the world’s greatest powers. When the war ended the events that followed over the next five decades had a great effect on the American people. There are some events that had more of an effect than others. This paper will discuss five major events over five decades that has had a powerful effect on the American people.Beginning in 1950 and ending in 1990, this paper will discuss the most significant events from each decade that either positively or negatively changed the American way of living. The communist scare took place in the 1950`s. McCarthyism, named after a man named Joseph McCarthy was a republican U. S. senator. In the 1950`s anticommunism created fear among the American people (McCarth yism, 2006). McCarthy played on Americans fears in an effort to better his political campaign. He instilled this fear by convicting anyone who was a part of the communist party or had anything to do with it.During court hearing Americans remained silent so that they wouldn`t be accused of communism. He accused some of the United States federal government of being communist and soviet spies. McCarthy was unable to prove his claims and was therefore censored by the American government (McCarthyism, 2006). Americans lost their jobs if they were accused of communism, library books were burned to hide evidence of communist acts. Americans suffered greatly during this time as they had to walk on around on egg shells (McCarthyism, 2006). IfAmericans did not agree with anticommunism, they were considered to be communist and were punished for not supporting the American way. People feared McCarthy, but it all ended when he made a public mockery of senate procedures (McCarthyism, 2006). He en ded his career to be known as reckless and dishonest man. Americans want peace took place in the 1960`s. The Vietnam War was well overdue considering some events that took place after World War II. How did America get involved in the Vietnam War? It all started with the Atlantic Charter. Franklin D. Roosevelt and Winston S.Church hill created this charter in hopes of a better world. Russia and China were not part of this charter and ultimately lead the U. S. to believe that Russia and China were involved in colonialism. Communism increased in South East Asia, mostly in Korea, Vietnam, China, and Cuba. The U. S. took action and attacked and conflict arose with Korea. The U. S. gets involved in Southeast Asia`s politics. North Korea invades South Korea. Nothing is accomplished and North Korea remains the same and South Korea remains the same. Next the U. S. inhabits South Vietnam.The U. S. helps rebuild South Vietnams economy. The U. S. tried to gain control over South Vietnams politi cs to avoid Vietnam turning communist. In 1965 North Vietnam attacked South Vietnam and American bases. North Vietnam lost the Vietnam War because they were no match for the American troops. The war had a dramatic effect on the American way of living. Americans rallied for peace and fell into the hippie era during the Vietnam War. During this time sex and drugs were on the rise. New drugs were introduced to the American people as the drug population grew.People began to have more sex during this time, which may have something to do with the increased drug use. The hippie era was a way of Americans expressing themselves of how they felt about the war. Many people wrote songs that told stories of things that were going on during that time. Mainly people wanted the war to end. Americans wanted peace, and sex, drugs and music was their way of getting away from it all. Detente took place in the 1970`s. Nixon`s visit to china in 1972 was an important step to build a relationship between A merica and China. This was the first time an American president had visited China.President Nixon visited China from February 21-28, 1972. Nixon reaffirmed interest for a peaceful settlement, and the U. S. continued to have relations with the Republic of China. Nixon was a strong advocate against communism so it surprised everyone when he went to visit china. He felt that if all nations cooperated with each other, then they could have reduced revenue and prevented a third world war. Nixon`s engagement with the communist was called Detente. Nixon held diplomatic conversations with China to establish a relationship and use that relationship against the Soviet Union.Nixon began the Nuclear Arms Reduction Treaty. Soon after came the end of the cold war. All About the Benjamin’s, took place in the 1980`s the decade of corporate greed. During this time Ronald Regan was the president and he was looking for a way to improve the American economy. His economic policy focused on focused on four points. First Regan wanted to reduce government spending, reduce income, reduce government regulation and control the money supply (Reagonomics 2010). His approach involved reducing tax cuts for wealthy Americans, and cutting funding for lower class Americans ( Reagonomics 2010).Regan felt if he cut funds for people on welfare that those Americans would try to get jobs. He introduced the earned income credit. He felt that this tax credit would be a way to encourage the unemployed to get out and work. Regan economic policies had both positive and negative effects on the American way of living (Reganomics 2010). The wealthy became richer and the poor became poorer. The unemployment rate declined but there was an increase in homeless and hungry Americans. Regan thought that he could create wealth for the U. S. by allowing business owners and free market corporations to compete for wealth.Reagan lowered the oil windfall profit tax. He lifted the petroleum price, deregulated air lines, and most of the airlines went bankrupt. He thought he could fix things that he could not fix. His motives were in the right place but the actions he took were not completely in the Americas best interest. Many Americans suffered during this time, but still Reagan was elected for a second term. He was liked by many. Some believe that Reganomics benefited America. Some of the policies introduced by Reagan are still being used today. Some of Reagan’s policies served as a blueprint on different ways to better the conomy. The Never Ending War took place in the 1990`s. In the books it is written that the gulf war began in August 1990 and ended in February 1991, but a war in Iraq still goes on today (1990`s, 2010). The gulf war was a war waged by the U. N. led by the United States and The United Nations against Iraq. Iraq troops invaded Kuwait in 1990 and brought immediate economic sanctions against Iraq. United States president George H. W. Bush sent American soldiers to Sau di Arabia six months later (1990`s, 2010). Many nations joined the coalition with America but America had the majority in military forces.Following The United States was Saudi Arabia, The United Kingdom, and Egypt (Gulf War, 2010). There had already been friction with Iraq and the United States that date back to the Cold War. Iraq was an ally of the Soviet Union (Gulf War, 2010). The United States had a concern involving Iraq`s position on Israel and Palestinian politics because Iraq disapproved of peace between Israel and Egypt. On August 12, 1990 Saddam Hussein wanted to compromise (Gulf War, 2010). He requested an immediate freeze of all boycott and siege decisions and wanted normalization of relations with Iraq.The United States expressed that there would be no negotiations until Iraq came out of Kuwait. Many resolutions were passed regarding the invasion made by Iraq. The most important was Resolution 678, passed in November of 1990, which set a deadline for Iraq to withdrawal from Kuwait (Gulf War, 2010). The deadline was for January 15, 1991. Ultimately if Iraq did not withdrawal but that time, they would have to be forced out. This brings us back to the coalition. Some countries did not join the coalition but sent money in support of it. Some countries did not want to increase U. S. nfluence in the Middle East (1990`s, 2010). In the end many nations were persuaded. Nations were promised economic aid, debt forgiveness or threats to withhold aid. Today the war in Iraq continues. There are still American troops overseas. How long will this war continue? It is unknown, but what is known is that this war has been indirectly been going on for decades, and all other wars and significant events before this war ultimately led to this one. So what is going to happen to America for the years to come? How will our current president deal with current issue that are results of past presidents decisions?America still has the same economic problems that Regan faced. W e are still at war with Iraq even after the first President Bush left office. In the future I see the war continuing. After the attacks of 9/11 I don’t think that The United States government would feel comfortable if they pulled all of the soldiers out of Iraq. I see the United States falling into a deeper depression. After all we are dealing with years of economic recovery. The unemployment rate over the past years has dropped. It is extremely hard for some people to get jobs.What is so hard to understand is how the United States began as one of the strongest countries economically, socially and politically and now we are falling so far behind. The United States is falling behind in education and this used to be the leading country in education. The United States has fallen behind in production. How could a country that is not social developed, compete with other countries that are so far ahead? It is unknown where the United States will be a decade from now but based on th e past compared to now, we might be dealing with same old issues.It may be worst. There may be more homeless, hungry, unemployed Americans a decade from now. The way the deficit is Funding for welfare programs may get cut again. Things are still the same. The rich are getting richer and the poor are getting poorer. If things do not soon change, there will be no hope for America’s future.Works CitedMcCarthyism. (2006, 8 23). Retrieved 11 23, 2010, from pbs. org: http://www. pbs. org/wnet/americanmasters/episodes/arthur-miller/mccarthyism/484/ 1990`s. (2010).Retrieved 11 28, 2010, from Wikipedia: http://en. wikipedia. org/wiki/1990s Gulf War. (2010).Retrieved 11 27, 2010, from Wikipedia: http://en. wikipedia. org/wiki/Gulf_War Vietnam War. (2010).Retrieved 11 23, 2010, from wikipedia: http://en. wikipedia. org/wiki/Vietnam_War

Virgin Mobile Marketing Metrics

Virgin Mobile’s business model consists of several different strategies for success. On July 2002, Virgin launched its new cellular service company, mostly geared for individuals ages 15- 19. The UK-based company had plans to acquire new clientele by tapping the youth market with the following tactics: Text messaging bundles: Virgin believed text messaging was a key selling point for youth as kids would often communicate with friends or family through this medium as it was cheaper than daytime minutes and a more discrete form of communication while in class.Ring Tones: Virgin offered a large selection of favourite and popular tunes and music that could be set as your cellular ringtone. Fun Clips: Are audio clippings of new gossip, sports information, jokes and other information that teens generally have interest in and have the time to review. Other features such as Music Messenger allowed cell phone users to share their favourite music with their friends and classmates.These features appealed more to the youth market and generated additional cell phone usage (if not by using minutes) and customer loyalty. Virgin believed that these mediums would bond customers to their phones therefore creating more interest. Virgin signed contracts with several phone manufacturers such as: Kyocera, Nokia, LG and more to enable a variety of phones to choose from; each providing a different benefit that would appeal to the youth.By adding these features and targeting the 15-24 market, as well as being a contract-free cell phone provider, this generated more interest in the market because the ones under 18 would have had to use their parents to sign a contract for them in order to have a wireless device, this way, Virgin enables customers the freedom. Assuming the number of customers is 5 in year one, and retention rate is 75% the decline in customers yearly thereafter will be deducted by the same percentage.By taking the number of effective customers in 2001 and multiply ing it by retention rates we acquire the pattern or deduction. (copy and pasting the formula along the years 2002, 2003, 2004, 2005 and 2006; the five-year wireless contract). | | | | | | Retention rate was calculated by assuming the number of total customers was 100. 25 customers left to another service provider. 100-25 = 75. (75/100) *100 = 75% Retention. Tab 1 of spreadsheet Tab 2 of spreadsheet

A Young Athlete Research Paper Example | Topics and Well Written Essays - 750 words

A Young Athlete - Research Paper Example r affection for games amid supplementary things had distinguished them from non-Greeks therefore, solitary Greek populace were permitted to contend in the games. (Camp 2004) In ornamentation, procedure of construction and appearance, Panathenaic amphorae had pursued conventional ethnicity for generations. The Vase in above picture is of 24  ½ in height and as of current situation it is conserved at the Metropolitan Museum of New York. (www.metmuseum.org n.d.) The Vase is carbon dated as of manufactured around 530 B.C. and belonged to the vast culture of Greeks. The painting style of the Amphora above matches with other works of the â€Å"Euphiletos Painter.† (Hyman 2006) The figures on one side of vase materialized as black shadows in opposition to the orange of the fired up clay, the details (fig 1.0) were carved into the beautification prior to firing the sculpture into the Kiln. (Hyman 2006) The rest of the Vase is adorned with slip that transformed into black color when exposed to heat in the kiln. The wholly established black-figure method, with additional crimson and white particulars and notching for sketches and particulars was invented in â€Å"Corinth† at some stage in the early 7th B.C. and lately launched into â€Å"Attica† almost post a gap of generation. (Camp 2004) Subsequently it thrived until the finish of the 6th BC. The â€Å"red-figure method† (Hyman 2006) which was conceived in 530 B.C. overturned this practice by way of the Vases being decorated black and the outlines painted with bright crimson colors, as in the case of above illustrated Vase. On front side of this vase, decorated by the â€Å"Euphiletos Painter† is Athena, â€Å"the Greek goddess of perception, combat, the arts, commerce, honesty and talent† (Gates 1972) equipped with a helmet and shield together with holding in the air a spear which is belligerently tramping to the fore. Beneath the arm of Athena, there is â€Å"the snake-fringed edge of her aegis, the goatskin with the

STRATEGIC MANAGEMENT Essay Example | Topics and Well Written Essays - 500 words - 2

STRATEGIC MANAGEMENT - Essay Example Through these, the company has remained in position to control their finances, their demand, supply rotating around labor supply, the raw materials supply and even the supply to the market has remained controlled hence influencing the business and the company’s growth. The company dominates a value chain that with its Chandlerian model in industrial administration aspects. An integrated company has a high level of vertical integrity applicable in defining their brand to the market. The sector matrix through the dynamics held internally has grown to have a positive impact to the general performance of the organization. Their targets of mass markets and standardized products dominant in quality make them a company to reckon with in the automotive industry. Through these, the demand for the company’s products and their supply remains on a positive scale weighing well for the owners of the company. The positive results it boosts of result from these making it a good example for the case on sector matrix. A bad example on the sector matrix is that of the Lehman Brothers. A company that was closed down due to the poor management of their supply and demand factors. The failure of the company was leveled on the financial crisis that the world faced during the great depressions and financial turmoil experienced in 2008. The poor preparation effects and the failure to detect and proactively plan from down times also mark the company’s failure. The demand factor was handled well by the company. The challenges met that drew the company down included the supply effects. The failure to control and sustain the demand and the pressure exerted on the financial position of the company and the supply chain changes made the company close down. Aspects of sector matrix aim at controlling factors of demand and supply. The demand for the services that the company offered was high though at

Influence of McDonald's Company on the State of the US Economy Essay

Influence of McDonald's Company on the State of the US Economy - Essay Example The primary challenge currently facing McDonald’s is the worsening state of the US economy, as concerns mount about a possible recession. In late January, the company reported a $1.2 billion fourth-quarter profit but warned of weakness in the US market. Same-restaurant sales were essentially flat in Dec. 2007, sparking fears that the one-month result might portend a trend. It was the growth in international sales that allowed for the company’s overall gains. The American market is the company’s largest and most crucial, with over 14,000 locations (â€Å"McDonald’s Posts Profit†). A Feb. 8 company press release reinforced the concerns about the domestic market, with US comparable sales only up 1.9 percent, while for Europe and the Asia/Pacific, Middle East and Africa bloc, sales were up 8.2 and 7.8 percent, respectively (â€Å"Strong Global Results†). If the current US slowdown leaks into the global marketplace, companies like McDonald’s may no longer by able to count on foreign sales to bolster the bottom line. The economic woes in America are tightening many pocketbooks and forcing even habitual fast-food customers to cut back. After decades of economic expansion and ever-growing consumer expenditures, signs are legion that the days of easy credit are over and that belt-tightening measures are becoming more the norm than the exception across the American landscape. The unfolding housing bubble collapse has had a major impact, as have continued nationwide job contractions. Even value-oriented businesses like McDonald’s are likely to be hit by potential customers staying home rather than coming out to their restaurants (Goodman 1). In addition, food prices have been rising steadily as have oil and gasoline costs, putting a severe squeeze on the average American consumer. In February, consumer confidence fell to its lowest level since 1992, according to a closely watched national survey. All of this is causing consumers to cut back on non-essential items (Grynbaum 1). Food is not a non-essential item, but the challenge to McDonald’s management is to revive stagnant domestic sales by convincing more potential consumers that they are better served by visiting their local restaurant as opposed to making meals at home. Once a significant enough number of people become convinced of this, it would help to break same-restaurant sales in the US out of its current flat-growth pattern.

APA Annotation for 4 articles Research Paper Example | Topics and Well Written Essays - 1000 words

APA Annotation for 4 articles - Research Paper Example The paper succeeds in demonstrating that the perception of Muslim women that is portrayed in the book undermines the need to address the patriarchal societies that make it difficult for the girl child to be empowered. Instead, it shows that the background of the author and financial motivations mostly drives the message. The paper is useful when evaluating the situation of Arabic Muslim girls in the United States of America. Although the paper serves as a strong critique of the book, it has failed to appreciate the truths in the novel. The Breadwinner has succeeded in contributing to the conversation about the role of religion in undermining the faith for equality in the society. The Arabic students in the country would identify with the argument made in the paper. In particular, they will identify with the fact that the institutional structure and culture where they learn often undermines the role of women. Moreover, they will agree that the ‘girl in need of salvation’ narrative that is present in the book undermines their quest for recognition in the society. , Erick and Zaidi focus on how the media covered the murder of a young Muslim girl in Mississauga, Ontario. The incident occurred in December 7. In particular, they have focused on how the media shifted the conversation from concerns over a tragic family event to a larger topic, the clash of civilizations. The authors also focused on tolerance and the negative effect that the term has on the society. The paper has highlighted the cultural implications involved in the debate over the hijab. Since Canada and America share many cultural similarities, the paper will be informative in shaping conversations on the topic in America. The paper highlights the ethical implications in the society. The authors have succeeded in highlighting the impact of an event in