Relationship of frictional force related to the sinkage depth Essay Example

Relationship of frictional force related to the sinkage depth Paper The graph above shows the data that establishes the relationship between rolling resistance of the bicycle and the sinkage depth of the tire on the sand bed. The relationship is found to be linear and is the only linear relationship in the whole experiment . As the sinkage depth of the tire increases the rolling resistance of the tire also increases . This shows that rolling resistance is directly proportional to sinkage depth . As we saw above the relationship between sinkage depth and the air pressure of the tire is varied and at the best can be explained by a polynomial trend . Arriving at the final conclusion for the rolling resistance based on the sole evidence of the sinkage depth on behalf of the air pressure of the tire. We can state that in order to determine the best possible value for the least resistance we would have to arrive at the a value offers the least sinkage depth for a given air pressure in order to attain the least rolling resistance the tire faces and optimize the force efficiency . Rolling resistance in this case is primarily caused due to a characteristic of a deformable material such that energy of deformation is greater than the energy of recovery . We will write a custom essay sample on Relationship of frictional force related to the sinkage depth specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Relationship of frictional force related to the sinkage depth specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Relationship of frictional force related to the sinkage depth specifically for you FOR ONLY $16.38 $13.9/page Hire Writer In this case the rubber component of the tire causes hysteresis , a property characteristic to elastic tires . The hysteresis causes the tire tire to lose energy due to the constant stretch and recovery . Looking at the results obtained from the experiment and the trends observed it can be stated that the primary cause that has affected the rolling resistance by the tire due its sinkage depth is the compressibility of the sand and the elasticity of the tire . The compressibility of the sand or compaction resistance is usually produced in this case by the work done by the cycle in making a rut of the depth . Another factor affecting the rolling resistance due to the sinakge depth is the amount of sand displaced by the tire in displacing the soil. The wheel compresses in the sand pushes out the sand from its original place. Hence as the work done by the bicycle increases in order to remove the sand from the original place the rolling resistance increases. The bulldozing resistance is mitigated by the fact that a portion of the soil is pushed to the sides of the wheel. The results from the experiment show polynomical trend rather than a linear trend . the most desirable data for the rolling resistance would be the sinkage depth as the rolling resistance force is directly proportional to the sinkage depth . The graph starts off with a sinkage depth of 0. 98 cm due to 49. 04 kPa and decreases until it reaches 0. 2 cm from which the value of the sinkage depth starts to increase . At 147. 12 kPA the tire has a considerable amount f air inflated . The amount of the air inflated is between the range of the air pressure classified as underflated an overflated. The ideal air pressure which in this case is 147. 12 kPa increases the thread area of the tire on the sand bed , increasing the width of the tore on the sand which causes the force of the tire on the sand to be spread out in the surface rather actually penetration the sand bed . At 49kPa and 98kPa there the tire is almost mildly inflated . With the tires fully inflated capacity being 320. 26kPA , these two pressure allow the tire to be inflated just 15. 3% and 30. 6% of their maximum capacity respectively . While pedaling the bicycle because of the lack of the air pressure of the tire and bicycle frame comes in close contact and force the sidewalls of the tire to flex due to the force that is being applied and pushes the bicycle deep into the sand bed due to this flexing phenomenon . From the above data we cannot establish linear relationship between air pressure and sinkage depth . There are many factors that affect the sinkage depth of a tire due to the air pressure . The air pressure of the tire causes the tread material in the tire to expand as it is partially filled and when the tread material is on the sand it adjusts the frame and the tread in a suitable manner . However as the air pressure in the tire increases and the tire is capacity for the air pressure reduces , the air that is present in the tire has less freedom to move around so as to adjust the frame and the tread of the tire in order to efficiently place itself . Hence as the air pressure in the tire begins to fill the tire up completely the sinkage depth in the tire increases . The air pressure in the tire limits the thread from spreading out the force on the sand and hence on a surface area of the sand as the force increases because it can’t be spread out the pressure on the sand increases and the tire sinks in deeper . Our research question which formed the basis of the essay was How does change in Sinkage depth of a tire affect the rolling resistance . The main of this experiment was to establish a relationship between sinkage depth of the tire and the rolling resistance it faces . The experiment involved allowing a bicycle , with specific air pressure which was measured using an air pressure gauge , with trainers to roll down a wooden ramp of length 5 meters and width 3 metres inclined at an angle of 45 ° to the ground . The bicycle after rolling down from the ramp rolled on a sand bed that was smoothened and softened by hand . The sand was wetted by adding 250cm3 of tap water in a linear manner , in order to make the sand retentive of the sinkage marks made by the tire. The reading of the sinkage depth was measured with the help of a vernier caliper. Consequently, the rolling resistance was calculated using these values . At the end of the experiment we successfully derived a linear relationship between the sinkage depth of the tire and the rolling resistance. The rolling resistance that the tire faces is directly proportional to the sinkage depth of the tire. Hence as the sinkage depth of the tire increases so does the rolling resistance 9it faces . In order to find the air pressure of the tire propagates the rolling resistance , we have to find the air pressure which has the least rolling resistance value . The absolute uncertainties that were obtained in our experiment for the rolling resistance were low , this shows that the values that we have obtained are precise . Performing this experiment at a small scale makes the rolling resistance negliblie. The devices that were used to measure the numerical values had a low least count . From the results that have been , there is a high possibility of the presence of random errors since the values that have been recorded show an inconsistency at unlikely events during the experiment. The experiment involved focusing on a variable and its outcome on a particular event . At best this approach can be considered incomplete as there are others factors present in the experiment that might affected the rolling resistance equally if not partially . There is a high possibility that the temperature also a major impact on the experiment and hence further areas for research include involving temperature as a variable in deciding if sinkage depth alone affects the rolling resistance linearly . Another area left for research and investigation is to find a quantitative data for the rolling resistance coefficient. In the experiment we found several data for the rolling resistance co-efficient , however we couldn’t compare this to a literature value due to a lack of research of bicycles on sand . Limitations in the model The limitations in the experiment that has been performed mainly arises from the various assumptions that have been made . The sand that was used as for the sand bed was procured from an open sea beach. Although the sand was smoothened and sieved there is a high possibility that the sand contained minute impurities such as small fragments of shell which might have had an counter-effect on the compressibility of the sand. It is also possible that the there was a high content of salt deposits on the sand as the sea water contained salt and the water from the sand had evaporated leaving behind salt deposits on the sand . We could have instead used soil instead as a surface bought from the market as this would be possibly have more uniformity than the sand . As mentioned in the method of investigation , the cycle had trainers attached to them while it rolled down the ramp in order to balance the cycle as it rolled down and prevent it from falling over . Since the trainers are wheels it is possible that they too contributed to the rolling resistance that the bicycle faced . However since all the quantitative values were recorded when the cycle was attached with trainers , the trainers have uniformly affected the rolling resistance in each trial and hence has no overall effect on the trend . The experiment also involved pouring a specific amount of water on the sand in order to increase the retentive ability if the sand . However , what has not been established in the experiment is the right amount of water that should be added to sand in order to increase the retentive ability . An increased amount of water in the sand will reduce the elasticity of the sand even though increasing the retentive ability of the sand. This will be detrimental to the experiment the actual sinkage depth of the tire will be reduced . Also , water was poured on the sand only once during the experiment . there is also a possibility that the water evaporated during the experiment , hence reducing the retentive ability of the sand and causing a discrepancy in the values obtained. The experiment was performed on in the outdoors during the day . The heat of sunlight was transferred to these materials used in the experiment , but since these materials have different thermal absorption capacitates their temperature might have varied. an abrupt increase in temperature induces a transient friction response similar to that induced by a step decrease in velocity ( Chester , 2012 ) . Since sand has a higher thermal capacity than wood the change in the temperature might cause a discrepancy . in order to control this variable we could have performed the experiment indoors with the temperature controlled by an air conditioner at 25a µC .

How the U.S. Is Countering Terrorism

How the U.S. Is Countering Terrorism Terrorism is not new, nor is the practice of trying to prevent it through  counterterrorism  measures. But as the number of terrorist attacks has skyrocketed in the 21st century, the United States and other nations have had to become much more proactive in defending their citizens from such violence.   Counterterrorism in the U.S. The U.S. government has made fighting terrorism a priority since the early 1970s, following the terrorist attacks on the 1972 Summer Olympics in Munich, Germany, and several airline hijackings. But it was the Sept. 11, 2001, terrorist attacks that made counterterrorism a pillar of domestic and foreign policy in the U.S. and beyond. The RAND Corporation, a defense policy think tank, defines the ongoing war on terror this way: Counterterrorism, since 2001, threatens terrorist safe havens, infiltrates terrorists financial and communications networks, hardens critical infrastructure, and connects the dots among the intelligence and law enforcement communities... Several federal agencies play critical roles in contemporary counterterrorism, both domestically and internationally, and often their efforts overlap. Among the most important are: Department of Homeland Security: The lead agency in charge of all domestic anti-terrorism and security activities.Department of State: Manages  the development and implementation of all U.S. government policies and programs aimed at countering terrorism overseasOffice of the Director of National Intelligence: Coordinates the gathering, analysis, and sharing of data among federal intelligence agencies such as the FBI and CIA.Federal Bureau of Investigation: Executes counterterrorism actions such as surveillance and investigation in conjunction with other law-enforcement agents at the local, state, and federal level.Central Intelligence Agency: Collects, analyzes, and shares international intelligence and data to inform and carry out U.S. foreign policy.National Counterterrorism Center: Plans  and coordinates counterterrorism policies and programs among federal agencies Fighting terrorism isnt limited to these agencies. The Department of Justice, for example, is responsible for prosecuting terror-related criminal cases, while the Department of Transportation frequently works on security issues with Homeland Security. State and local law enforcement agencies are often involved in some capacity as well.   On an international level, the U.S. government frequently cooperates with other countries on matters of security. The United Nations, NATO, and other nongovernmental organizations also have established counterterrorism policies of their own. Types of Counterterrorism Generally speaking, counterterrorism efforts have two goals: to protect the nation and its citizens from attack and to neutralize threats and actors who would attack the U.S. Defensive measures can be simple, like placing concrete bollards in front of buildings to stop an explosive-laden vehicle from getting too close. Video surveillance of public areas coupled with facial-recognition technology is another, considerably more advanced defensive counterterrorism measure. The security lines at U.S. airports, operated by the Transportation Security Agency, are yet another example. Offensive counterterrorism measures can range from surveillance and sting operations to arrests and criminal prosecutions to seizing financial assets and military action. In February 2018, for example, the Treasury Department froze the assets of six people known to conduct business with Hezbollah, an Islamic organization the U.S. has labeled a terrorist organization. The 2011 raid by Navy Special Forces on Osama bin Ladens Pakistan compound, which resulted in the death of the Al Qaeda leader, is one of the best-known examples of successful military counterterrorism activity. Sources Jenkins, Brian. Bush, Obama, And Trump: The Evolution Of U.S. Counterterrorist Policy Since 9/11. ICT.org.il. 24 September 2017.Lederman, Joshua. Taking Aim at Iran, US Hits Hezbollah With New Sanctions. StarTribune.com.  2 February 2018.Roser, Max; Nagdy, Moses; and Ritchie, Hannah. Terrorism. OurWorldInData.org. January 2018.United Nations staff. UN Global Counter-Terrorism Strategy. UN.org.  United States Department of State. Country Reports on Terrorism 2016. State.gov. July 2017.

Hunahpu and Xbalanque - The Maya Hero Twins

Hunahpu and Xbalanque - The Maya Hero Twins The Hero Twins are famous Mayan semi-gods called Hunahpu and Xbalanque, whose story is narrated in the Popol Vuh (â€Å"The Book of Council†). The Popol Vuh is the sacred text of the Quichà © Maya of the Guatemalan highlands, and it was written during the Early Colonial period, probably between 1554–1556, although the stories within it are clearly much older. The First Hero Twins Hunahpu and Xbalanque are the second Hero Twins in Maya mythology. Like all Mesoamerican cultures, the Maya believed in cyclical time, including periodic cosmic destruction and renovation, called the ages of the world. The first pair of divine hero twins were the Maize Twins, 1 Hunter Hun Hunahpu and 7 Hunter Vuqub Hunahpu, and they lived during the second world. Hun Hunahpu and his twin brother Vucub Hunahpu were invited down into the Maya underworld (Xibalba) to play the Mesoamerican ballgame by the Xibalban lords One and Seven Death. There they fell prey to several trickeries. On the eve of the scheduled game, they were given cigars and torches and told to keep them lit all night without consuming them. They failed in this test, and the penalty for failure was death. The twins were sacrificed and buried, but the head of Hun Hunapu was cut off, and only his body was buried with his younger brother. The Lords of Xibalba placed Hun Hunapus head in the fork of a tree, where it helped the tree bear fruit. Eventually, the head came to look like a calabash- the American domesticated squash. A daughter of one of the lords of Xibalba named Xquic (Blood Moon) came to see the tree and Hun Hunapus head talked to her and spit saliva into the maidens hand, impregnating her. Nine months later, the second Hero Twins were born. The Second Hero Twins In the third world, the second pair of hero twins, Hunahpu and Xbalanque, avenged the first set by defeating the Lords of the Underworld. The names of the second set of Hero Twins have been translated as X-Balan-Que â€Å"Jaguar-Sun† or â€Å"Jaguar-Deer,† and Hunah-Pu, as â€Å"One Blowgunner.† When Hunahpu (One Blowgunner) and Xbalanque (Jaguar Sun) are born, they are treated cruelly by their half-brothers  but make themselves happy by going out every day to hunt birds with their blowguns. After many adventures, the twins are summoned to the underworld. Following in the footsteps of their fathers, Hunahpu and Xbalanque descend the road to Xibalba, but avoid the tricks that captured their fathers. When they are given a torch and cigars to keep alight, they trick the lords by passing off a macaws tail as the glow of a torch, and by putting fireflies at the tips of their cigars. The next day, Hunahpuh and Xbalanque play ball with the Xibalbans, who first try to play with a ball made of a skull covered with crushed bone. An extended game follows, full of trickery on both sides, but the wily twins survive. Dating the Hero Twins Myth In prehistoric sculptures and paintings, the Hero Twins arent identical twins. The older twin (Hunahpuh) is depicted as larger than his younger twin, right-handed and masculine, with black spots on his right cheek, shoulder and arms. The sun and pronghorn antlers are Hunahpuhs main symbols, although often both twins wear deer symbols. The younger twin (Xbalanque) is smaller, left-handed and often with a feminine guise, with the moon and rabbits his symbols. Xbalanque has patches of jaguar skin on his face and body. Although the Popol Vuh dates to the Colonial period, the Hero Twins have been identified on painted vessels, monuments, and cave walls dating to the Classic and Preclassic period, as early as 1000 BCE. The names of the Hero Twins are also present in the Maya calendar as day signs. This further indicates the importance and antiquity of the myth of the Hero Twins, whose origins date back to the earliest period of Maya history. Hero Twins in the Americas In the Popol Vuh myth, before avenging the fates of the first twins, the two brothers have to kill a bird-demon called Vucub-Caquix. This episode is apparently portrayed in a stela at the early site of Izapa, in Chiapas. Here a couple of young men are portrayed shooting a bird-monster descending from a tree with their blowgun. This image is very similar to the one narrated in the Popol Vuh. The myth of divine hero-twins is known in most Native American traditions. They are present in myths and tales both as legendary ancestors, and heroes that need to overcome various trials. Death and rebirth are suggested by many of the hero-twins appearing in the form of men-fish. Many Mesoamerican Indians believed that gods catch fish, human embryos floating in a mythical lake. The Hero Twin myth was part of a suite of ideas and artifacts that arrived in the American southwest from the gulf coast beginning about 800 CE. Scholars have noted that the Maya Hero Twin myth appears in southwestern United States Mimbres pottery about that time. Updated by K. Kris Hirst Sources Boskovic, Aleksandar. The Meaning of Maya Myths. Anthropos 84.1/3 (1989): 203–12. Print.Gilman, Patricia, Marc Thompson, and Kristina Wyckoff. Ritual Change and the Distant: Mesoamerican Iconography, Scarlet Macaws, and Great Kivas in the Mimbres Region of Southwestern New Mexico. American Antiquity 79.1 (2014): 90–107. Print.Knapp, Bettina L. The Popol Vuh: Primordial Mother Participates in the Creation. Confluencia 12.2 (1997): 31–48. Print.Miller, Mary E., and Karl Taube. An Illustrated Dictionary of the Gods and Symbols of Ancient Mexico and the Maya. London: Thames and Hudson, 1997. Print.Sharer, Robert J. The Ancient Maya. 6th ed. Stanford, California: Stanford University Press, 2006. Print.Tedlock, Dennis. How to Drink Chocolate from a Skull at a Wedding Banquet. RES: Anthropology and Aesthetics 42 (2002): 166–79. Print.-. The Popol Vuh: Definitive Edition of the Maya Book of the Dawn of Life and the Glories of Gods and Kings. 2nd ed. New York: Touc hstone, 1996. Print.

Japan and American politics Essay Example | Topics and Well Written Essays - 750 words

Japan and American politics - Essay Example Their motto being â€Å"Japanese spirit, Western things†. This is easily discernable by their deep involvement in the modern economic growth of their own country as well as the East Asia, yet their refusal to give up their own culture and sense of identity. This is not limited to the clothes they wear, or the language they speak, but can also be discernable by the customary practices of the Japanese in their offices as well as their clinging to local traditions that help maintain harmony in their lives. There is no denying that this form of modernization has been successful in maintaining balance and harmony in the lives of the Japanese, both at home and at work in corporations. They have successfully brought together their own culture with the economic policies of the West. However, sometimes the â€Å"Japanese spirit, Western things† slogan has been given another meaning by the anti-liberal Japanese, who want to amalgamate Western technology in such a way into the Japanese system that it would protect them from political competition and protect their interests alone. Hence, the slogan is used to protect economic and political threat to their powers, which they refuse to share or give up. This causes a lot of problems for the Japanese economy, as it results in bad businesses carrying on with little or no respite for the investors, and the bad or weak corporations continuing their business with little or no accountability, and often by a monopoly. Albeit, this slogan has helped maintain Japanese identity and has enabled them to have their own place, culturally and economically in the world, however, it has resulted in many a losses, which include the losses resulting from their refusal to allow competition and private enterprising in many domestic sectors, as Japanese culture is hostile towards competition in the economic life. Moreover, the Japanese back bad banks, and refuse to close down even those

English Class Writing Assignment Essay Example | Topics and Well Written Essays - 500 words

English Class Writing Assignment - Essay Example Their chance came when Carl was recruited to work in the U.S. Navy with both the father and son expecting too much from this break, not knowing he will just be helping in the kitchen, giving him the mocking of his own color. While on break on the deck, Carl and his co-workers were watching the divers do their exercises and being lured by the waters; the young man readied himself to dive, against the will of his companions and the white Americans. When an attempt was made to make him get out of the water, he swam towards the middle of the sea with skill that impressed the trainer. He was then promoted as a diver, allowing him to see the dangers of his job. When an accident happened that called for an immediate rescue, Carl witnessed Billy Sunday, played by Robert DeNiro, do the rescue without any diving gear to protect him in the water, with all passion and fervor to his duties, dived against his commander’s will. This event led to a sickness that prevented him from continuing with his responsibilities, thus, was appointed to training master divers. Carl boldly went to the trainer who promoted him and expressed his wishes to become what he wanted, a master diver. The trainer laughed at this idea because black men are not allowed to be in the U.S.

Rolfing :: Research Physical Muscle Essays

Rolfing Rolfing is a scientific and organized system of manipulating the muscles in the body to their correct positions. Rolfing is a controlled approach within the general field of structural integration. Rolfing was originally called "structural integration." Some people still use the words, structural integration, instead of Rolfing (www.smart.net/~astro/define.html). Developed by Ida P. Rolf, Ph.D., this practice includes the process of teaching the body how to move by manipulating the body. People that are involved in Rolfing believe that the versatility and harmony of the body has to do with how the body deals with the field of gravity. Gravity is the most powerful force that affects the human body. The goal is to balance the body, and the main objective is to be in harmony with the body (www.lyrisys.com/LinSilver/). Rolfing restructures and educates the body to move in a specific manner. It releases the tension in the tissues which hold the bones and organs together to let the body r e-align or balance itself with the force of gravity. Since Rolfing gives the body a better balance, it takes less energy to fight against gravity. It re-educates the body's movement patterns. Movement in the body becomes simpler and there is an improvement in daily functions (www.igrin.co.nz/business/rolfing2.htm). In the 1930's and 1940's, Dr. Ida P. Rolf was a biochemist who studied the movement and function of the corrective tissue. Fifty years ago, Dr. Rolf named her work structural integration, but today it is known as Rolfing. She was interested in finding out about long-term contractions by pointing out the faults of the muscle tissues. She had a son that was ill and no doctor could find the cure. Then, she realized that the problem was within her son's body. The internal organs were being compressed. She started to massage her son, and the pain her son was feeling began to disappear (www.concentric.net/~wkaye/HistoryPage.html). Dr. Rolf worked in creating a holistic system of manipulating the tissues and educating the body's movement in symmetry with gravity. She found that by guiding the body's system with posturing and structuring, people could begin to feel changes in their body. Rolfing was the nickname that was given after the founder, Dr. Ida Rolf (www.rolf.org/intro.html). Af ter giving many lectures and writing many books, she founded the Rolf Institute to teach others the concept of Rolfing (www.concentric.net/~wkaye/HistoryPage.html). The main goal in Rolfing is to align the body to its original state.

The Popularity of Fast Food Restaurants

Why are fast food restaurants so popular? That question in now very popular. Some people around the world still don’t understand why the fast food restaurants are still popular, despite the eventual inconveniences mentioned daily. I think that fast food restaurants are popular because of their availability, they avoid cooking, and because of their prices. One of the causes of the popularity of fast food restaurants is their availability. Indeed, people can find fast food restaurants everywhere.Nowadays, those restaurants are built on the main streets, in business buildings and in the neighborhood in order to allow a quick access to their clients. For example, there is a fast food restaurant at North Lake College. Whether I like or not, it’s the nearest restaurant that I can find when I have a break. Therefore, I will obviously go there to grab something for not being hungry during the coming classes. Consequently, the availability is on the cause of the popularity of fa st food restaurants.Another cause of the popularity of fast food restaurants is that they allow us not to cook. Indeed, some people may be very busy by their job, a project or a school program, which does not allow them enough time to cook. Therefore, they will be tempted by an easier choice, which is the fast food restaurant. Why? Simply because the fast food restaurants are faster than normal restaurants, so they allow people to spend more time on their job, or projects. In addition, some people do not know how to cook.Therefore, these restaurants are help for them. Furthermore, you can find different menus in these restaurants, which give a large choice of foods to the clients. Consequently, the fast food restaurants are popular because they allow people to avoid cooking. A last cause of the popularity of fast food restaurants is the price. As you know, the fast food restaurants are the cheapest you can find. Not everybody has the opportunity, or the money to afford for a lunch i n a restaurant. Therefore, people prefer to spend their money in fast foods.In addition, in order to save, some people are more tempted to buy fast foods than to eat in restaurants. Consequently, the price is another of the popularity of the fast food restaurants. In conclusion, the fast food restaurants may be popular because of their availability, they avoid cooking, and because of their prices. Being available everywhere, allowing people to avoid some household tasks, and even allowing them to save money are some of the reasons that make the fast food restaurants very popular.