An Idealized Model in Physics

I once heard an acronym for the best pieces of physics advice I ever got: Keep It Simple, Stupid (KISS). In physics, we are typically dealing with a system that is, in reality, very complex. For an example, lets consider one of the easiest physical systems to analyze: throwing a ball. Idealized Model of Throwing a Tennis Ball You throw a tennis ball into the air and it comes back, and you want to analyze its motion. How complex is this? The ball isnt perfectly round, for one thing; it has that weird fuzzy stuff on it. How does that affect its motion? How windy is it? Did you put a little bit of spin on the ball when you threw it? Almost certainly. All of these things can have an impact on the motion of the ball through the air. And those are the obvious ones! As it goes up, its weight actually changes slightly, based on its distance from the center of the Earth. And the Earth is rotating, so perhaps that will have some bearing on the relative motion of the ball. If the Suns out, then theres light hitting the ball, which may have energy repercussions. Both the Sun and the Moon have gravitational effects on the tennis ball, so should those be taken into account? What about Venus? We quickly see this spiraling out of control. Theres just too much going on in the world for me to figure out how all of it impacts on me throwing the tennis ball? What can we do? Use in Physics In physics, a model (or idealized model) is a simplified version of the physical system that strips away the unnecessary aspects of the situation. One thing that we dont typically worry about is the physical size of the object, nor really its structure. In the tennis ball example, we treat it as a simple point object and ignore the fuzziness. Unless its something were specifically interested in, well also ignore the fact that its spinning. Air resistance is frequently ignored, as is wind. The gravity influences of the Sun, Moon, and other heavenly bodies are ignored, as is the impact of light on the surface of the ball. Once all of these unnecessary distractions are stripped away, you can then begin focusing on the exact qualities of the situation that youre interested in examining. To analyze the motion of a tennis ball, that would typically be the displacements, velocities, and gravity forces involved. Using Care With Idealized Models The most important thing in working with an idealized model is to make sure that the things youre stripping away are things that are not necessary for your analysis. The features that are necessary will be determined by the hypothesis that youre considering.   If youre studying angular momentum, the spin of an object is essential; if youre studying 2-dimensional kinematics, it may be able to ignore it. If youre throwing a tennis ball from an airplane at high altitude, you may want to take into account wind resistance, to see if the ball hits a terminal velocity and stops accelerating. Alternately, you may want to analyze the variability of gravity in such a situation, depending on the level of precision you need. When creating an idealized model, make sure that the things youre eliminating are traits that you actually want to eliminate from your model. Carelessly ignoring an important element isnt a model; its a mistake. Edited by Anne Marie Helmenstine, Ph.D.

M1903 Springfield Rifle - World War I

The M1903 Springfield rifle was the primary rifle used by the United States Army and Marine Corps during the first several decades of the 20th century. Officially designated United States Rifle, Caliber .30-06, Model 1903, it was a bolt-action rifle that utilized a five-round magazine. The M1903 was used by the American Expeditionary Forces in World War I and was retained after the conflict. It was not replaced as the standard American infantry rifle until the introduction of the M1 Garand in 1936. Despite this change, the M1903 was still in use during the early campaigns of World War II. In the years after the war, only the M1903A4 sniper rifle variant remained in the inventory. That last of these were retired during the early years of the Vietnam War. Background Following the Spanish-American War, the U.S. Army began seeking a replacement for its standard Krag-JÃ ¸rgensen rifles. Adopted in 1892, the Krag had shown several weaknesses during the conflict. Among these was a lower muzzle velocity than the Mausers employed by Spanish troops as well as a difficult to load magazine which required the insertion of one round at time. In 1899, attempts were made to improve the Krag with the introduction of a high-velocity cartridge. These proved unsuccessful as the rifles single locking lug on the bolt proved incapable of handling the increased chamber pressure. Development Design Over the next year, engineers at the Springfield Armory began developing designs for a new rifle. Though the U.S. Army had examined the Mauser in the early 1890s prior to selecting the Krag, they returned to the German weapon for inspiration. Later Mauser rifles, including the Mauser 93 used by the Spanish, possessed a magazine fed by a stripper clip and a greater muzzle velocity than its predecessors. Combining elements from the Krag and the Mauser, Springfield produced its first operational prototype in 1901. Soldier with M1903 Springfield. U.S. Army Center for Military History Believing they had achieved their goal, Springfield began tooling its assembly line for the new model. Much to their dismay, the prototype, designated M1901, was declined by the U.S. Army. Over the next two years, the U.S. Army laid out a variety of changes which were incorporated into the M1901s design. In 1903, Springfield presented the new M1903, which was accepted into service. Though the M1903 was a composite consisting of the best elements from several prior weapons, it remained similar enough to the Mauser that the U.S. Government was forced to pay royalties to Mauserwerke. M1903 Springfield Cartridge: .30-03 .30-06 SpringfieldCapacity: 5 round stripper clipMuzzle Velocity: 2,800 ft./sec.Effective Range: 2,500 yds.Weight: approx. 8.7 lbs.Length: 44.9 in.Barrel Length: 24 in.Sights: Leaf rear sight, barleycorn-type front sightAction: Bolt-action Introduction The M1903 was officially adopted on June 19, 1903 under the official designation of United States Rifle, Caliber .30-06, Model 1903. In contrast, the British and Commonwealth forces used the Lee-Enfield Rifle. Moving into production, Springfield built 80,000 of the M1903 by 1905, and the new rifle slowly began to replace the Krag. Minor changes were made in the early years, with a new sight added in 1904, and a new knife-style bayonet in 1905. As these alterations were implemented, two major changes were introduced. The first was a shift to pointed, spitzer ammunition in 1906. This led to the introduction of the .30-06 cartridge that would become standard for American rifles. The second change was a shortening of the barrel to 24 inches. World War I During testing, Springfield found that the M1903s design was equally effective with a shorter, cavalry-style barrel. As this weapon was lighter and more easily wielded, it was ordered for the infantry as well. By the time the US entered World War I in April 1917, 843,239 M1903s had been produced at Springfield and the Rock Island Arsenal. Equipping the American Expeditionary Forces, the M1903 proved lethal and efficient against the Germans in France. During the war, the M1903 Mk. I was produced which allowed for the fitting of a Pedersen device. Developed in an effort to increase the M1903s volume of fire during assaults, the Pedersen device allowed the rifle to fire .30 caliber pistol ammunition semi-automatically. World War II After the war, the M1903 remained the standard American infantry rifle until the introduction of the M1 Garand in 1937. Much beloved by American soldiers, many were reluctant to switch to the new rifle. With the entry of the US into World War II in 1941, many units, both in the U.S. Army and Marine Corps, had not completed their transition to the Garand. As a result, several formations deployed for action still carrying the M1903. The rifle saw action in North Africa and Italy, as well as in the early fighting in the Pacific. A GI with the 36th Infantry Division cleans his M1903 Springfield, equipped with sniper scope. Public Domain The weapon was famously used by the U.S. Marines during the Battle of Guadalcanal. Though the M1 replaced the M1903 in most units by 1943, the older rifle continued to be used in specialized roles. Variants of the M1903 saw extended service with the Rangers, Military Police, as well as with Free French forces. The M1903A4 saw extensive use as a sniper rifle during the conflict. M1903s produced during World War II were often made by Remington Arms and the Smith-Corona Typewriter Company. Later Use Though it was reduced to a secondary role, the M1903 continued to be produced during World War II by Remington Arms and Smith-Corona Typewriter. Many of these were designated M1903A3 as Remington requested several design changes to improve performance and simplify the manufacturing process. With the conclusion of World War II, most M1903s were retired from service, with only the M1903A4 sniper rifle being retained. Many of these were replaced during the Korean War, however the U.S. Marine Corps continued to use some until the early days of the Vietnam War.

The Roles and Achievements of Prime Ministers Free Essays

Name Tutor Course Date The Roles and Achievements of Prime Ministers John a Macdonald and Laurier Sir John a MacDonald was the first prime minister of Canada and was the dominant representative of the Canadian confederation. He was born on the 11th January 1815 and passed on 6th June. His term in office was 18 years long which places him to the second longest serving prime minister in Canada. We will write a custom essay sample on The Roles and Achievements of Prime Ministers or any similar topic only for you Order Now He is the only one to ever win six majority governments (Hennessy 12). As for Sir Wilfrid Laurier, he was the seventh prime minister, Born on 20th November 1841 and passed on on the 17th February 1919. He was the first francophone prime minister and was considered one of the countries superb statesmen. As compared to his counter part John a MacDonald, sir Wilfrid was also in the list of the longest serving prime ministers in Canada although him coming in as position four. Sir Wilfrid also contributed to the expanding of the confederation. Sir John MacDonald was born in Glasgow Scotland was the third in a family of five while Sir Wilfrid laurier was born in Saint-lin Canada East and was the 7th generation of his family. MacDonald’s parents decided that he should become a lawyer after his completion of schooling. It was a great choice for a boy who seemed to really admire studying and beside that he had an urgent to start earning cash in order to support his family since his fathers business ventures were failing. As compared to Macdonald Lauriers’ father was well up and by the age of eleven he was sent to study in new Glasgow. Macdonald had a rather sorrowful and tragedous private life. When Sir Macdonald first came into office he was faced with major opposition. Nova Scotia was already threatening to withdraw from the confederation; the Anglo-American relationships were in a poor state. In 1867 the first general elections were held and this is where MacDonald had his first major achievement. He was able to bring together Nova Scotia New Brunswick and the province of lower and Upper Canada to form the state of Canada of which guaranteed him election stress free. MacDonald’s main vision was to enlarge the country and bring it together in unity. Under his rule he rought British Colombia, PIE, and great North West territories into Canada all this for ? 300,000 (about $11,500,000 in modern Canadian dollars). Macdonald’s still biggest achievement as a prime minister was the building of the Trans continental railway which was completed in 1891 (Leonardo 219). He also managed to create a god relationship with the United States rising to the challenge of the Northwest rebellion and his balancing of French and English interests in accept able terms for most. Sir Wilfrid Laurier is known to have had a number of accomplishments as a prime minister. To begin with he was able to establish the department of labour and external affairs, he also managed to recruit immigrants into the west, and in 1905 he oversaw the creation of two provinces Alberta and Saskatchewan into the confederation which saw the creation of the last two provinces in the Northwest Territories (Picknett, Prince, Prior Brydon 290). He also saw the beginning of the two new transcontinental railways although the project was filled with scandals. He also made a deal with the united state for lower rates on natural products. The two prime ministers are to date considered being the greatest of all time. This Great statesmen had a couple of similarities if we scrutinses them properly. One similarity was that both of them were students of law. MacDonald studied law in Toronto where he traveled by boat whereas sir Wilfrid studied law in New Glasgow. These two men had a vision of the expansion of the country of Canada since both of them contributed to the increase of the confederation. Sir MacDonald helped bring the provinces of Upper and Lower Canada, Nova Scotia, and New Brunswick together in 1867 to form Canada while Sir Wilfrid Laurier had the provinces of Alberta and Saskatchewan created in 1905 which saw the last spit of the Northwest Territories. Sir Macdonald oversaw the establishments of the first transcontinental railway and Sir Wilfred Laurier also oversaw the establishment of tow more transcontinental. Sir MacDonald negotiated the relation ship with the United States and this was also exhibited by sir Wilfrid. The above similarities signify that both of the prime ministers were both devoted and dedicated to the development of Canada. These similarities only signify their similarities in ensuring a proper Canada but these two men had other similarities because they were both the first in whatever they did. MacDonald was the Prime minister of Canada while Sir Wilfrid Laurier was the first francophone prime minister. In the common life Sir MacDonald and sir laurier had a couple of differences . Sir MacDonald came from a family that was not all that well up as compare do to sir Wilfred, he studied law in order to be able to put a meal on his families table since all his fathers ventures were crumbling as compared to Wilfred who studied Law as his passion. Sir Wilfred and Sir MacDonald left a legacy in Canada and are both commemorated in big ways. Both of them have the pleasure of having holidays celebrated in their hournor; they both have avenues named in their respect such as the Laurier Avenue. These two statesmen had very minimal similarities and difference and these was due to their characters but both will live to be legends as far as Canada is concerned. Works Cited Hennessy, Peter. Prime Ministers: The Office and its Holders since 1945. Cambridge: Cambridge Press, 2001. Leonardo, Gordon. Review of Prosperity and Misery in Modern Bengal: The Famine of 1923–1944. American Historical Review, 88. 4 (1983): 218 – 230. Picknett, Lynn, Prince, Clive, Prior, Stephen, and Brydon, Robert. War of the Windsors: A Century of Unconstitutional Monarchy. Chicago: Mainstream Publishing, 2002. How to cite The Roles and Achievements of Prime Ministers, Essay examples