Young Modulus of Copper Essay Example for Free

Young Modulus of Copper Essay Theory The following quantities is important for the experiments concerns: Stress is defined as ? =Force / Cross-sectional area ( F/A ) Strain is defined as ? = Extension / Natural length ( e/l ) The ratio of Stress to Strain, is the Young modulus (E= ?/?) Since a stiffer material requires larger stress to produce the same strain , a stiffer material would have a greater Young modulus ( a greater slope in a graph of ? against ? ) . For a non brittle material, usually there are two stages of deformation before breaking. Stage 1 : Elastic deformation In this stage, the wire would return to its natural length when the stress is removed. Hookes law is usually obeyed in this stage, therefore the graph is almost a straight line. When the wire is further stretched, it reaches the elastic limit and get into stage 2. Stage 2 : Plastic deformation In this stage, the stress is not directly proportional to the strain and and a small amount of stress can produce a large strain. If the wire passes the yield point, its will have permanent extension and will not return to its original length. Finally, when the wire is kept to stretched, it will break at the breaking point. Procedure Experiment 1: Study the stress-strain behaviour of a copper wire 1.A micrometer screw gauge was used to measure the diameter of the copper wire at several points. Mean value was taken and the cross-sectional area of the wire was calculated. 2.A pulley was mounted on one side of the table. A 2 m segment of the wire was cut out and was clamped firmly by using a G-clamp which was at a distance about 1.5 m form the pulley. 3.The wire was placed over the pulley. Some newspapers were put one the ground below the pulley. 4.A label marker is sticked on the wire at a distance about 0.5 m from the pulley. A metre rule was placed below the wire and was fixed on the table by sticky tape. 5.A 100g hanger was tied to wire. 6.The length between the G-clamp and the sticker, which represents the natural length, was measured. 7.100g load was added to the hanger one by one , and the extension was recorded each time. 8.Load was kept increasing until the wire broke. Experiment 2 : Elastic deformation and Young modulus 1.A new wire of the same length and thickness was used and steps 1 to 7 in experiment 1 were repeated. 2.Load was added to the hanger carefully. All the load were removed each time to check whether the wire would return to the original length. Results were recorded. 3.Step 2 was repeated until the elastic limit was just exceeded. Precautions 1.The hanger should be more than 0.5 m above the newspapers. This allows the wire to get enough space for extensions before it breaks. Also it should not be kept too high from the ground, this may cause the tiles of the floor to break. 2.The sticker should not be placed too close to the pulley. If not the wire may touch the pulley when the wire is extended. A distance of 0.4 m is preferred. 3.The load should be added to the hanger slowly and carefully. This is to avoid exerting impulse to the wire and making the masses to oscillate. Otherwise the wire may get extra extension and make the records not appropriate. 4.Records should be taken only after the sticker stops moving. This is because the wire takes time to extend itself, especially at the later stage when the wire passed the elastic limit and was near breaking. Results Diameter of the copper wire: D1 D2 D3 D4 Mean Value (in à ¯Ã‚ ¿Ã‚ ½0.005mm) 0.370 0.365 0.670 0.370 0.3688 Natural length of the wire=1.15m Experiment 1: Load(kg) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Extension(10^-3 m) 0 0.5 0.5 1 1 1.5 1.5 2.0 Load(kg) 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 Extension(10^-3 m) 2.5 2.5 3.0 3.0 3.5 4.0 5.5 12 Load(kg) 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Broken Extension(10^-3 m) 19 34 46 60 77 98 125 / Maximum load for elastic deformation=1.3 kg Load for breaking the wire=2.3 kg Experiment 2 : Load(kg) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Extension (10^-3) 0 0.5 0.8 1 1.2 1.5 1.5 2 Load(kg) 0.9 1 1.1 1.2 Elastic limit exceeded Extension(10^-3) 2.5 2.5 3 3.5 / / / Calculations Graphs Maximum possible error of metre rule = 0.1 cm=0.01m Maximum possible error of micrometer screw gauge =0.005mm=510^-6 m Cross-sectional area of the wire = 1.06810^-7 m^2 Percentage error = 26.77810^-3 =1.3557% ?Cross-sectional area = (1.071 à ¯Ã‚ ¿Ã‚ ½ 0.01)x10^-7 m^2 Experiment 1 Stress Strain relationship: Stress (M Pa) 9.345 18.69 28.03 37.38 46.73 56.07 65.42 74.76 Strain (10^-3) 0 0.4348 0.4348 0.8696 0.8696 1.304 1.304 1.7392 Stress (M Pa) 84.11 93.45 102.8 112.1 121.5 130.8 140.1 149.5 Strain (10^-3) 2.174 2.174 2.609 2.609 3.043 3.478 4.783 10.44 Stress (M Pa) 158.9 168.2 177.6 186.9 196.3 205.6 215.0 Broken Stress (10^-3) 16.52 29.57 40.00 52.61 66.96 82.61 108.7 / Stress at elastic limit=124 M Pa Percentage error=Percentage error of the area of the wire =1.3557% ?Stress at elastic limit=(124 à ¯Ã‚ ¿Ã‚ ½ 2)M Pa Breaking stress=(215 Pa à ¯Ã‚ ¿Ã‚ ½ 3)M Pa Experiment 2: Stress Strain relationship up to elastic limit: Stress (M Pa) 9.345 18.69 28.03 37.38 46.73 56.07 65.42 74.76 Strain (10^-3) 0 0.4673 0.7477 0.9346 1.121 1.402 1.402 1.869 Stress (M Pa) 84.11 93.45 102.8 112.1 Elastic limit exceeded Strain (10^-3) 2.336 2.336 2.804 3.271 / / / Mean of the stress=60.7 M Pa Mean of the strain=1.5610^-3 Slope of the best-fit line=38.9 G Pa Maximum slope=42.2 G Pa Minimum slope=30.0 G Pa Mean error=(38.9-36.1)=2.8 G Pa ?Young modulus of the copper wire=(38.9 à ¯Ã‚ ¿Ã‚ ½ 2.8)G Pa Errors and Difficulties 1.There were systematic errors in this experiment. The masses were not weighted to check what its actual weight is. The wire may not be made of pure copper. The air temperature may vary due to air-conditioners. Besides, gravitational acceleration is taken as 10ms^-2 instead of 9.8ms^-2 2.There was a random error in viewing the sticker. Since the sticker had a few distance from the ruler, errors due to parallax would arise if we view form a little bit right or left. So it is difficult to obtain the precise value. To improve this, a nail can be added onto the sticker. The nail was more stable and gave readings very sharply. 3.At the beginning of the experiment, the wire is very uneven. The first few extensions we taken may be only due to the reform of the wire into a straight shape.(just like stretching a spring into a straight wire) Discussion 1.Near the breaking point, the shape of the wire is very narrow. 2.During elastic deformation, the hanger falls and loses gravitational potential energy. This energy change to elastic potential energy. If the wire is unloaded, the energy will be restored to GPE and the wire will return to is original length. 3.During plastic deformation, the loss of gravitational potential energy becomes the work done to increase the length of the wire (increase the separations of the particles in the wire). This energy would not be restored even the wire is unloaded. 4.Double of the amount of the load is required to break the wires. Conclusion To obtain the Young modulus of the copper wire by this experiment is convenient. A few apparatus and steps are needed, and it only involves easy calculations. But by comparing to the actual value(124G Pa), the result we get (38.9 G Pa) has a great difference from it. This may due to the experiment is done in several assumptions and estimations. We assumed g=10ms^-2 and the wire is made of pure copper. We neglected environmental factors and assumed the wire was stretched evenly in every parts. In short, although the experiment is not accurate enough, it provides a good chance for students to practice what they have learned. It is quite shocked that a very thin and long wire can withstand more than 2 kg load.

Jane Eyre By Charlotte Brontë :: English Literature

Jane Eyre By Charlotte Brontà « Jane Eyre by Charlotte Brontà « was published in 1848, under the name of Currer Bell. Although the novel is over 150 years old, there are still themes that we can relate to today, such as bullying, prejudice and hypocrisy. In this essay, I am going to discuss the three themes mentioned and also consider admirable characters from the novel; the authors narrative technique and the part that I found appealing. The first issue that I will discuss will be on the bullying that Jane received at Gateshead Hall: the home of her Auntie and cousins. She is bullied by not just her cousins, but her aunt as well. In Chapter one, it shows the bullying from her cousins and aunt, when she has begun reading and John Reed, her cousin, throws the book at her head, and she retaliates. But because she retaliated, John's sisters ran up to their 'mamma' and blamed the fight on Jane. She was then escorted upstairs and locked in the red room. This could be counted as a form of bullying, as she only puts her in the red room as a punishment for attacking John, but we, the readers, already know that John started all of the commotion. Verbal bullying is also used in chapter one, where John Reed calls her names for throwing a punch at him (QUOTE: CHAPTER1/LINE 16: "I don't very well know what I did with my hands, but he called me 'Rat!, rat! ') During Jane's First term at Lowood, Jane is bullied out of food, when there was very little and the older girls wanted some more food to devour. Jane Eyre is a first-person narrative, related in the voice of the protagonist, or heroine. Jane Eyre is the "I" of the story, the person whose voice we hear as we read, and everything that happens is seen from her point of view. Nowhere in the novel does the author break the flow of the narrator's voice to give us an objective view of her main character. However, she does remind us once in a while that the story is being told by Jane as a mature woman, looking back on events that happened some years earlier. The mature Jane occasionally comments on the younger Jane's reactions to those events, and sometimes she even addresses you, the Reader, directly. You'll also find occasions where her narrative includes long stories told to Jane by other characters (such as Rochester's accounts of his past), conversations that Jane overhears between other characters, and even accounts of Jane's dreams. These not only add variety to the style but give the reader a Jane Eyre By Charlotte Brontà « :: English Literature Jane Eyre By Charlotte Brontà « Jane Eyre by Charlotte Brontà « was published in 1848, under the name of Currer Bell. Although the novel is over 150 years old, there are still themes that we can relate to today, such as bullying, prejudice and hypocrisy. In this essay, I am going to discuss the three themes mentioned and also consider admirable characters from the novel; the authors narrative technique and the part that I found appealing. The first issue that I will discuss will be on the bullying that Jane received at Gateshead Hall: the home of her Auntie and cousins. She is bullied by not just her cousins, but her aunt as well. In Chapter one, it shows the bullying from her cousins and aunt, when she has begun reading and John Reed, her cousin, throws the book at her head, and she retaliates. But because she retaliated, John's sisters ran up to their 'mamma' and blamed the fight on Jane. She was then escorted upstairs and locked in the red room. This could be counted as a form of bullying, as she only puts her in the red room as a punishment for attacking John, but we, the readers, already know that John started all of the commotion. Verbal bullying is also used in chapter one, where John Reed calls her names for throwing a punch at him (QUOTE: CHAPTER1/LINE 16: "I don't very well know what I did with my hands, but he called me 'Rat!, rat! ') During Jane's First term at Lowood, Jane is bullied out of food, when there was very little and the older girls wanted some more food to devour. Jane Eyre is a first-person narrative, related in the voice of the protagonist, or heroine. Jane Eyre is the "I" of the story, the person whose voice we hear as we read, and everything that happens is seen from her point of view. Nowhere in the novel does the author break the flow of the narrator's voice to give us an objective view of her main character. However, she does remind us once in a while that the story is being told by Jane as a mature woman, looking back on events that happened some years earlier. The mature Jane occasionally comments on the younger Jane's reactions to those events, and sometimes she even addresses you, the Reader, directly. You'll also find occasions where her narrative includes long stories told to Jane by other characters (such as Rochester's accounts of his past), conversations that Jane overhears between other characters, and even accounts of Jane's dreams. These not only add variety to the style but give the reader a

Low Pressure Atmospheric Systems

Low pressure atmospheric systems are also known as depressions or cyclones and they form in mid- and high-latitudes. They are formed by the mixing of cold and warm air, the warm air is lighter, so it rises above the denser, cold air and forms a centre of low pressure. High pressure atmospheric systems are also known as anticyclones and have very different characteristics to depressions. Anticyclones are large masses of subsiding air, which produces high pressure at the surface.There are a variety of difference between anticyclones and depressions, including the weather conditions, the length of time they last and the impact they have upon diverse countries and areas. Low pressure atmospheric systems can cause hazards because of severe weather such as blizzards and heavy snowfall, as well as high winds and heavy rainfall. This can have harsh impacts among individuals, being a lead cause of hypothermia, and frostbite, especially those vulnerable, such as the elderly. Also, these depres sions can cause crops to be destroyed, and a high mortality rate throughout the spring lambing season.Extreme cold spells can have a massive negative effect on a global scale, but also in a specific country or region. High pressure atmospheric systems affect the globe, especially the southern hemisphere, as it is nearly always continuous, although in places such as Australia and South Africa, this is broken throughout their summer. With anticyclones, there are few winds, so maps usually have circular spaced out isobars. Also, these atmospheric systems block depressions, which mean that their impacts are usually long-term, because they are constant. Weather associated with anticyclones differentiates depending on the time of year.In summer, anticyclones produce long periods of dry, hot, sunny weather, which can then cause heat waves and drought. However, in winter the cloudless nights mean that temperatures drop, and does not recover the next day because of weak sunshine and lingerin g fog. The impacts of anticyclones and depressions vary, as does the period they remain and the effect they have. The North American blizzard of 2003 lasted for five days throughout February and occurred on the East Coast of the USA and Canada. It was a record-breaking blizzard, which caused 27 deaths and over $14 million worth of damage.The cities in America were bought to a standstill, as there was a range of 38-76cm of snow covering the ground. The cause for such an unusually extreme blizzard was the fact that the conditions were favourable, with moisture from the Atlantic Ocean enhancing precipitation and a high pressure system over Canada, allowing cold air to be brought down coastal areas. This meant that the precipitation was mainly snow, hence the record-breaking statistics. The effects this storm had were mainly short-term, but the roof of the historic Railroad Museum collapsed and 27 people lost their lives.Additionally, transport infrastructure was brought to a halt, and three major airports were also closed. So, the impacts of depressions are mainly short-term, although the destruction can be horrendous, whereas, anticyclones usually cause long-term impacts on a country such as the Drought in Britain and Europe in 2003. This drought effected many locations, but the main focus was on the UK, France and Portugal. Not all impacts are negative, as the heat wave did boost the tourist industry in most countries and sales for summer items such as barbeques and sun cream increased, but this positive outlook is short-lived.In the UK, an estimated 200 people lost their lives due to poor air quality, and this figure was 10% higher than the average. Furthermore, transport was disrupted because of roads melting at such high temperatures, and the London Underground was 37Â °, which is over the legal limit to transport animals. Finally, in the UK the cost of people taking days off work to enjoy the hot weather was between ?7. 5million and ?10million per day. In France, the death toll was as high as 30,000 and harvests were down by 30 to 50% on 2002.Additionally, the nuclear power plants could not produce the soaring demands for energy, which was used for refrigerators and air conditioning, because there was less water available for cooling. Portugal declared a State of Emergency after the worst forest fires in 30 years. Approximately 35,000 hectares of forest, farmland and scrub was burned, and 1300 people died. 80 families were forced to abandon their homes, and arsonists begun deliberately causing fires, to gain compensation. The impacts of anticyclones on all of these countries had a massive effect, and it lasted over a month, with the hottest temperatures for up to 500 years.This demonstrates the long and short term impacts that anticyclones have on regions, countries and on a global scale. Location does have a result on the impact of low and high atmospheric pressure systems because they can be underdeveloped or have a lot of technolo gy that can be damaged or ruined. MEDC’s usually lose fewer lives than LEDC’s, no matter if it is a depression or a cyclone. Also, the evidence seems to suggest that depressions have a shorter impact on an area than anticyclones, but this is not necessarily true.Long-term secondary hazards can be a large issue after a depression, as the damage from flooding or heavy snow can be excessive and highly damaging. I conclude, low pressure atmospheric systems do usually have shorter-term impacts on a location, rather than high pressure atmospheric systems, but the secondary hazards can be a long-term issue for both of these hazards. Furthermore, the impact they have, may be different, depending on location, because a LEDC will be severely affected by both of these hazards, and will most likely have long-term consequences.

The Progressive Period - 1544 Words

In 1901, America welcomed the youngest president to ever rule, President Theodore Roosevelt. At forty-two years old, the former New York governor dominated the news unlike any previous president had done. His many exploits, such as boxing and horseback riding, led the press to gain interest in him. Known for being very outgoing and likable, Roosevelt used his personality and popularity to advance in his programs. â€Å"His leadership and publicity campaigns helped create the modern presidency, making him a model by which all future presidents would be measured†(524). He felt that the government should take control when states show incompetence in dealing with problems. Roosevelt saw the presidency as a â€Å"bully pulpit.† He believed he could use†¦show more content†¦Pinchot advised Roosevelt to keep large tracts of federal land exempt from private sale. By doing this forests and grazing lands would be conserved. Making agriculture possible, under Rooseveltâ⠂¬â„¢s federal water projects, some dry wilderness areas were transformed. In 1902 the National Reclamation Act, also known as the Newlands Act, established the precedent that the federal government would manage that precious water resources of the West. Although Roosevelt failed to support civil rights for African-Americans, like most other progressives, he did support a few individual African-American rights. Even though some opposed, he appointed an African-American as the head of the Charleston, South Carolina, customhouse. When Roosevelt made a decision, he stuck with it. For example, he appointed a black postmistress. Even though some whites refused to accept the postmistress, Roosevelt chose to close the station rather than give in. However, in 1906, â€Å"Roosevelt angered many African-Americans when he dismissed without a question an entire regiment of African-American soldiers accused of conspiracy in protecting others charged with murder in Brownsville, Texas†(530) . Roosevelt even invited Booker T. Washington, who was then the African-American leader most respected by powerful whites, to the white house as a symbolic gesture. In 1905 a civil rights conference in Niagara Falls was held. The goal for this conference was to create complete equality between blacks andShow MoreRelatedHow Successful Were Progressive Reforms During the Period 1890-1915 with Respect to the Following? Industrial Conditions, Urban Life, and Politics2257 Words   |  10 PagesOver 32,000 soldiers and armed policemen crossed into the Rhineland. The Tydings-McDuffie Act - approved on March 24, 1934 was a United States federal law which provided for self-government of the Philippines and for Filipino independence after a period of ten years. Anschluss - was the occupation and annexation of Austria into Nazi Germany in 1938. El Alimein - Two important World War II battles were fought in the area. At the First Battle of El Alamein (July 1 – July 27, 1942) the advance ofRead MoreThe Progressive Era Of America1297 Words   |  6 Pages The Progressive Era was a period that changed America greatly due to political reforms and social activism. This era brought forth many changes in America and almost all Americans were involved in this movement somehow. This period began in the late 1800s and lasted until the mid-1900s. The Progressive Era was one of the biggest movements in America. The main point of this movement was to purify the government. Several historians have wrote excerpts on their perspective of the Progressive Era. GeorgeRead MoreThe Contributions Of The Progressive Era1294 Words   |  6 PagesTaking place in the United States between the 1890s and the 1920s, the Progressive Era was a period characterized by political reform and social activism. Due to the popularity of the Progressive ideals during this time period, American citizens elected for president candidates, such as Roosevelt, Taft, and Wilson, who subscribed to these ideals. Of the three Progressive presidents, Wilson was the most effective w hen it came to addressing the major issues of the late 19th and early 20th centuriesRead MoreLessons Learnt From the Great Depression and Progressive Era1386 Words   |  6 Pagesthe Great Depression Progressive Era Lessons from the Great Depression Progressive Era The Progressive Era in American history began slightly before the turn of the 20th century and continued into the second decade of the 20th century, ending around the beginning of World War I. The Great Depression of 20th century American occurred in 1929 and the more intense short-term effects lasted up and through World War II. The paper will scrutinize specific events of this period providing insight, elaborationRead MoreThe Progressive Era Of The Gilded Age1455 Words   |  6 PagesThroughout the progressive era there were many reform movements due to the abundance of political, social, and economical corruption in America in the gilded age as seen by political machines like William Marcy tweed and American financiers like J.P. Morgan. Some of the many issues that made themselves present in the gilded age include the large wealth gap, child labor, women’s lack of rights, influx of immigrants, Urbanization, Indian wars, monopolists, political machines, and alcoholism. All ofRead MoreEssay on A Progressive Movement1538 Words   |  7 PagesA Progressive Movement Much of a historian’s job is to read what their colleagues have written on their subject of interest at the moment. Often, they then go on to write their own opinions on the subject, thereby influencing the historians of the future. The famed historian and teacher Richard Hofstadter wrote The Age of Reform in 1955 about the late 19th century and early 20th century movement of Progressivism. In turn, other historians that include Paula Baker, Richard McCormick, andRead MoreProgressivism And Progressivism925 Words   |  4 PagesUnited States. Progressivism is defined as a movement that is to limit the social destructiveness effects of capitalism. Progressives look at capitalism as unhindered. That they need to extract from the markets in a capitalist system and to counterbalance the tasks that capitalism leaves such as terrible social effects. They wanted the public well being to be better off. Progressives overall did not want to other throw capitalism, but they wanted th e government and policies to be constrained to be inRead MoreThe First Midterm Assignment During American History1500 Words   |  6 Pagesprolonged time period in American history and also what the bloodiest. Many violent events occurred that gave the 19th century its name, such as, profound labor conflicts between boss and workers, the Indian wars that was an extended battle for peace and a benefit in their lifestyles, the Jim Crow law which was established to separate races throughout the city, and also the fight for the American Empires power. These were the major issues that made the 19th century an important time period in AmericanRead MoreThe Gilded Age : A Powerhouse Rose From The Ashes Of The Civil War871 Words   |  4 PagesProgressives in the Gilded Age The Gilded Age: A powerhouse rose from the ashes of the Civil War. From the Civil War until about 1896, the Gilded Age was born. The United States was going through an era of governmental, fiscal and societal restructuring. Gilded Age got its name because Mark Twain seen as a period where everything seemed to be well on the surface but beneath was a scheme of political dishonesty and self-indulgence. Around this time, the affluent upper class was created due to theRead MoreWomen, African Americans And Literature1747 Words   |  7 PagesWomen, African-Americans Literature in the Progressive Era One of the greatest turning points in American history was the Progressive era due to the advancements and social responses led by women and people of color. Many depictions of this era through secondary sources can be used to see the conflicts faced by the individuals of the time period and the political movement that ensued right after. Many favorable outcomes resulted from this time period including the start of reformation from women