The Epidemic Of HIV AIDS In Africa - Free Essay Example

Sample details Pages: 3 Words: 871 Downloads: 3 Date added: 2019/08/08 Category Medicine Essay Level High school Tags: AIDS (HIV) Essay Did you like this example? Peoples lives are at risk! Africa is currently experiencing a major HIV/AIDS epidemic. HIV/AIDS is an acquired immunodeficiency syndrome and a sexually transmitted disease. It can cause night sweats, fever, depression, fatigue, and loss of appetite. Don’t waste time! Our writers will create an original "The Epidemic Of HIV AIDS In Africa" essay for you Create order This horrendous disease is striking most of Africa. Many countries are in need of inspection, such as Tanzania, who has reached out and asked for help with multicultural. HIV/AIDS is creating chaos in Africa, specifically in Ethiopia, Nigeria, and Kenya.Ethiopia had over 250,000 deaths in 1990 due to HIV/AIDS, making it the hardest hit country in Africa. a total of 28,000 deaths due to AIDS and an estimated 800,000 AIDS orphans annually. When the children parents die of HIV/AIDS the children have no other choice, but to be put into orphanages. The rapidly increasing number of orphans each year will continue to grow in Ethiopia because HIV/AIDS is still a major issue. HIV/AIDS is transferred through sexual contact between males and females. HIV/AIDS is the major strain of virus in Ethiopia, transmission is largely through heterosexual contact and to a lesser extent to mother-to-child transmission. HIV/AIDS is likely to decrease the life expectancy of Ethiopians by 4.6 years because of all of the all of the babies being born with HIV/AIDS. It also causes an increase in the infant mortality rate because most babies are born dead due to HIV/AIDS from their mother. This outbreak in Ethiopia is going to cause the population to rapidly decrease. Ethiopians are taking action in preventing HIV/AIDS by assisting others affected and infected. They are providing others with the materials and support they need. Not far behind Ethiopia is Nigeria with its HIV/AIDS epidemic. Nigeria is home to 3.2 million people infected with HIV/AIDS. Making it the second largest population with HIV/AIDS. Most Nigerians that are infected are unaware that they have HIV/AIDS. This is due to the lack of methods of testing HIV/AIDS in Nigeria. There are not many doctors or hospitals in Africa, so there is not enough treatment present in Nigeria, causing more HIV/AIDS deaths.   Sex workers and low condom use are two major contributors to Nigerias epidemic. According to Nigerias National Agency for the Control of AIDS (NACA), sex workers, specifically women have had some behavioral changes. In July 2015, it found female sex workers to be using condoms regularly and increasingly aware of HIV risk. The Nigerian women are taking action in protecting thems elves from HIV/AIDS, which can aid in maintaining a healthy, long-living population. The use of condoms prevents transferring HIV/AIDS from person to person while performing sexual intercourse, thus contributing to a healthy population. With rare and expensive treatments, Nigerian families influenced by HIV/AIDS have to spend money very carefully, seeing that it is scarce due to medical expenses. When large expenditures go towards treatment and funerals, caregiving responsibilities increase and income is lost as a result of premature mortality. This will affect child education and nutrition. This will also cause a change in focus for the adults in the family, instead of maintaining a career and income, their focal point will be directed to caring for theirfamilies. HIV/AIDS also increases the mortality rate in Nigeria, due to all of the young HIV/AIDS cases who have died. Unlike Nigeria,  Ã‚  Ã‚  Ã‚  Ã‚   Kenya has been able to provide prevention for HIV/AIDS. Kenya is also a country in Africa that is highly affected by HIV/AIDS. However, they have had a decrease in new infections due to their prosperous HIV/AIDS prevention systems. Kenyas epidemic is being caused by the humiliation and discrimination Kenyans are afraid of if they choose to get tested for HIV/AIDS. By not knowing if they are infected or not, leaves the Kenyans that are infected at risk for death by HIV/AIDS. This will soon lead to huge death rates in Kenya. Ferreira and Pessoa (2003) consider a continuous-time model with premature mortality due to HIV/AIDS where an individuals decision about schooling depends on her life expectancy. Getting tested for HIV/AIDS is common sense, especially if they feel they show many of the symptoms. By not getting tested, they are putting themselves at risk as well as others. This is where the education or common sense role comes into play, as their decision to get tested depends on their life. The life expectancy in Kenya is most likely to decrease if Kenyans keep this poor mindset and fear being discriminated against getting tested for HIV/AIDS. Although there has been some success in preventing HIV/AIDS, this epidemic still resides as a problem in Africa. Affecting countries such as Ethiopia, Nigeria, and Kenya, HIV/AIDS has caused about half a million deaths in Africa. HIV/AIDS is caused by people engaging in unprotected sexual intercourse. Regardless of the steps taken to prevent HIV/AIDS it still remains a major issue. Steps such as programs to educate people about HIV/AIDS, treatment, and even condom supply have not been completely effective. HIV/AIDS affects the populatio n, life expectancy, and mortality rate because there is no cure. HIV/AIDS will continue to plague Africa until people begin to follow the necessary precautionary steps.

The Topic Of Legalizing Marijuana For Recreational Use

The topic of legalizing marijuana for recreational use has long been a controversial topic. Back in 1996, California became first state to legalize medical cannabis, lighting a fuse across the nation. Fast forward to the year 2012 and thus began states legalizing marijuana for recreational purposes. Those states were Colorado and Washington. Following those states was the announcement of Alaska voting to legalizing weed for recreational us in 2014. After them came Oregon and Washington D.C. in 2015 and in 2016 were the announcements California, Maine, Massachusetts, and Nevada. From this data one can see each year more and more states have decided to lower their conditions and punishments on the use marijuana. Politicians have even gone to†¦show more content†¦The vast majority of them were marijuana related. In 2012 Colorado had risen to third in the nation where college students were considered marijuana users at over 25 percent. At that time the national average was rough ly 19 percent (Stimson, 2014). The unintended consequences did not stop at the students either. Many Colorado natives and visitors took advantage of the new law by often driving while under the influence of marijuana. A great majority of DUI arrest involved marijuana and approximately 24 to 40 percent were marijuana alone. People were clearly more carefree when it came to driving and being under the effects of marijuana at the same time. In 2013, nearly 50 percent of Denver adult arrestees tested positive for marijuana, a 16 percent increase form 2008. Hospitalization related to marijuana increased 82 percent since 2008 (Stimson, 2014). Positive Consequences Just as there have been many cases of negative consequences for the legalization of marijuana†¦there have also been positive cases. Over the years, the marijuana industry has developed rapidly and generated thousands of new jobs. After the legalization of weed over 18,000 full-time jobs were created and added roughly 2.4 billion USD (US Dollars) to the state of Colorado’s economy. Colorado also accumulated over 10 million USD in taxes from retail sales in the first four months (â€Å"7 Ways Marijuana Legalization Has Already Benefited Colorado In Only 8Show MoreRelatedShould Marijuana Be Legalized?972 Words   |  4 PagesMarijuana Legalization For thousands of years, marijuana has been used for a myriad of purposes ranging from medical use to recreational use. Although small steps are being for marijuana legalization across the country, there is still a long way to go. Some folks argue that marijuana is a gateway drug and impairs judgement, causing people to act recklessly. However, extensive studies have been conducted on the effects, risks, and benefits of marijuana, and have proven marijuana to be safer thanRead MoreEssay on Legalizing Recreational Marijuana in the United States1131 Words   |  5 PagesThe topic of legalizing recreational marijuana in the United States has been a very controversial one. States such as Colorado and Washington have gone on the offensive and have legalized recreational marijuana and have enjoyed the high revenues brought in from cannabis sale. On the other hand other states have kept low profiles because they are wary of the possible negative outcomes of legalizing recre ational marijuana and are using the states of Colorado and Washington as guineaRead MoreEssay about Should Marijuana Be Legalized in the United States?1569 Words   |  7 PagesThe topic of legalizing recreational marijuana in the United States has been a very controversial one. States such as Colorado and Washington have gone on the offensive and have legalized recreational marijuana and have enjoyed the high revenues brought in from cannabis sale. On the other hand other states have kept low profiles because they are wary of the possible negative outcomes of legalizing recreational marijuana and are using the states of Colorado and Washington as guinea pigs to see whatRead MoreIt Is Time to Legalize Marijana1700 Words   |  7 Pagesregardless. I remember being told this my entire life and even to this very day. But as I got older I realized that people would still use drugs even though it’’s illegal. I could never understand why someone would go against the l aw and jeopardize their life just to use drugs? The drug that I am talking about is marijuana, and surprisingly it is all around us. Marijuana is even referred to in today’s media Mainstream media sources that people enjoy, like music, movies, and TV shows, do not even botherRead MoreShould Marijuana Be Legalized? Essay1372 Words   |  6 Pagesregardless. I remember being told this my entire life and even to this very day. But as I got older I realized that people would still use drugs even though it’s illegal. I could never understand why someone would go against the law and jeopardize their life just to use drugs? The drug that I am talking about is marijuana, and surprisingly it is all around us. Marijuana is even referred to in today’s media Mainstream media sources that people enjoy, like music, movies, and TV shows, do not even botherRead MoreLegalization of Marijuana1550 Words   |  7 PagesLegalization of Marijuana: Benefits and Statistics The topic of legalizing marijuana has been a topic of controversy for quite some time now not only throughout our local streets, but throughout the local and into the state government. The legalization of marijuana is such a controversial topic because some are for it and some are against it. People are for the legalization because of the great uses it has towards medicine, the money that could come from the taxation of legalized marijuana, and theRead MoreThe Myths Of Legalizing Marijuana1601 Words   |  7 PagesThe Myths of Legalizing Marijuana A controversial social topic surrounding our time has been the issue of legalizing marijuana for recreational purposes. Cannabis sativa, also known as marijuana, was classified by the United States government as a class I drug in 1970, which means that it is against the law to possess and distribute this illegal substance (Source 2). However, in recent years, many states have made marijuana more accessible for medical and recreational use. States such as ColoradoRead MoreShould Marijuana Be Legalized? Essay1587 Words   |  7 Pages Legalization of Marijuana Marijuana is not a recent discovery, but the mysteries surrounding the controversial topic in question remains to be disputed since its prohibition. Classified as an illegal substance, cannabis has been restricted in Canada and around the world. Marijuana is a complex drug and its contradictory claims of medical purposes, and harmful destruction, fuel the debate on whether or not the legal constraints of consuming marijuana should be reconsidered. In consideration of academicRead MoreEssay on Research on Legalizing Marijuana1492 Words   |  6 PagesLegalize It Lobdell 1 Legalize It Legalizing Marijuana has been a controversial and extremely volatile topic ever since the 1970’s. Many people hold strong beliefs regarding this topic and the subsequent laws that have been passed in certain states for the use of the recreational drug. However, marijuana is not just a recreational drug, but has many different wonderful medical purposes for the American people. Marijuana should be legalized for recreational and medical purposes throughout this countryRead MorePersuasive Essay On Legalizing Marijuana1746 Words   |  7 PagesLegalizing Marijuana Can you imagine being just six-years-old and suffering from over three hundred violent seizures a week? From birth, Charlotte Figi suffered from a rare form of epilepsy, which caused these seizures. After trying everything to help Charlotte, her parents finally decided to try medical marijuana, and it worked! Charlotte still had seizures, but now, she had maybe two or three seizures a month instead of three hundred a week. Charlotte’s story and many similar stories, along

Management Strategies and Social Responsiveness †Free Samples

Question: Discuss about the Management Strategies and Social Responsiveness. Answer: Introduction The aim of the assignment is to analyse the energy company called Enron established in Houston Texas. The key components of the report include discussion of the companys failure towards its stakeholders with a brief discussion on the infamous Enrons scandal. Further report identifies and analyses the organisational behaviour factors that contributed to the failure followed by the SWOT analysis of the company. The report highlights the strength and he weakness of the company and analyses the opportunities and threats. The remedial response taken by the company to address the failure is discussed briefly and strategies to overcome such failure is recommended. Ken Lay created Enron in 1986, an energy company established in Houston Texas. Within ten years of span, it was recognised as seventh largest company in Texas. The company was involved in transmission and distribution of the power. The crucial factor that led to the failure of the company towards its stakeholders is the unethical leadership. The leadership issues for the purpose of gaining prosperity made the company bankrupt. It effected all the stakeholders of the company including the investors, creditors, thousands of employees, senior executives, suppliers, clients, shareholders, community and the government (Prebble 2016). Description of the event The company failed to cope up with the internal and external situation due to lack of competency and ethical leadership. The managing directors of the company were driven by the goal of profit maximisation and Jeffrey Skilling employed the narcissistic leadership. It is the destructive leadership where the subordinates and the employees were dominated for selfish motto of the organisation. The top executives of the company breached the code of conduct (Broni et al. 2017). The company started with the innovative idea of buying electricity from different companies and selling it to individual customers while charging everyone along the way. This ground breaking idea generated enormous profit and led to competitive environment. The company focused on share price tactics obsessively. It purchased the electricity and deliberately shut down the power plant in California due to increase in value of the power outages. Major cash drain occurred due to excessive compensation plan. The company misled the investors and the creditors with false financial information. Enron manipulated the energy market, and earned money at the immense cost of others. The firm projected itself as highly profitable, growing company. This later turned out to be a negative popularity as analysing the companys financial statements showed massive debts that were concealed in a manner to show profits. However, the auditors did not perform their duty well and failed to highlight the red f lags. After the performance evaluation, the lowest portion of the employees was fired without consideration (Dibra 2016). It had impacted the stakeholders of the company financially and emotionally. Other financial firms, banking, insurances and brokerages were drawn into the legal battles. Organisational behaviour (OB) refers to the behaviour of leaders and the employees in the work that differs from that in social setting and effects the management in the organization. A companys success is determined by the organisational behavioural factors such as culture, change management, motivation, and decision making (Hosseini and Mahesh 2016). In this context the OB factors that contributed to the Enrons scandal and failure towards stakeholders are- unethical leadership, dominating culture, inappropriate decision making-authority and poor management controls that led to faulty corporate governance structure (Stahl et al. 2016). Analyse the identified OB factors According to Broni et al. (2017), the employees are likely to act ethically if the managers and the executives of the company lead in ethical direction. Enron did not maintain the ethical standards that resulted in the breakdown of the corporate governance and culture. The autocratic and dominative leadership created a pessimistic culture where the leaders demanded only conformity. The leaders focused on profit-making, obsessed with the bottom line and penalised employees for dissent (Markham 2015). Therefore the employees too accepted the unethical acts in daily duties due to cutthroat competition. Employees did not report the harsh organisational behaviour for fearing of losing jobs and considered the leadership trait of integrity as non-factor (Meymandi et al. 2015). Employees are motivated with rewards that are fair and equitable. The auditors did not honesty disclose the financial statements of Enron. These employees completely lost the integrity to speak the truth as they were rewarded for obeying dishonest rules in Enron ad focusing on profit. In order to know the massive debts and real financial situation of Enron one of the important group member Andrew Fastow, gave external motivation to the employees (Tan and Yeo 2013). The poor cooperate governance in the Enron was attributed to egoism or self interest of the top executives. These leaders put their own interests above those of their employees, and public. The company failed to shoulder responsibilities for unethical events. According to Friedman and Gerstein (2017), a companys culture can be influenced positively if the managers are clear about the vision and values and practicing them on a daily basis. This aspect was lacking in Enron and is evident from the lack of transparency in financial accounting. Innovation and creativity in the organisation is simulated by informed risk taking. This proves requires robust, effective communication between employee and executives. In any organisation, the decision-makers should have adequate experience and information for delegation of decision-making authority (Shapiro and Stefkovich 2016). In case of inappropriate delegation of decision was observed as the company radically shifted to new risk-taking business areas without having risk managing skills. At higher level the new risk-taking financial schemes lacked a certain degree of control. It was found that the chief financial officer of the company operated without professional accounting qualification. In acc ounting system the performance evaluation revealed five types of manipulations. There was no information sharing with employees (Breevaart et al. 2014). This internal mechanism that is playing the decisive role indicates poor corporate governance. SWOT of Enron SWOT analysis is the useful tool to determine the strength and weakness of the company, the opportunities and threats. It can be defined as a systematic model that gives direction to develop the market plan. SWOT indicates what an organisation can do and cannot do, the favourable conditions available for success (Alleyne 2016.). The SWOT of Enron is presented below Strength Weakness Opportunities Threats Marketing and value delivery Human capital pool Innovative company During failure the weaknesses observed are- Failed board of directors Conflicts of interests Unethical practices Corporate culture The innovative strategies of Enron provided many favourable conditions- Supply of high quality energy Clean energy Business merger and acquisition Market development in Asian countries Threats due to global environment and the external business are- Increase in competition Regulation Subprime Mortgage crisis Terrorist threats Analyse the companys strength and weaknesses Enron met the needs of the clients and the customers by robust marketing strategies. It was successful in delivering the customer value at profit which was strength of the company. According to Khan (2017) human capital is the factor that determines the success of the company. Enron was using experienced skill set that has helped it to manipulate the accountings and the financial statements while manipulating the regulations in the logical way. They recruited pool of workers who intelligently used different accounting standard. This aspect was both positive in terms of profit generation and negative in terms of unethical behaviour. As Enron was involved in five different lines of businesses, the large number of employees was having a big chunk of stocks or shares. Innovative strategies more than following the mundane guidelines make a business successful (Mariani 2017). Shifting to energy trading company from the energy and natural gas transportation was an innovative idea. With the expansion of the business the Enron was gaining more and more financial support from the top most financial institutes (Prebble 2016). According to Markham (2015) it is the role of the board of directors to act through its committee and monitor the business to be ahead of developments both in and out of corporation and address the limitations. In addition to monitoring, the directors should evaluate the decisions of the management, reflect on its influence and actively design an alternate plan. However, Enron failed to take these steps. Enrons board of directors failed to delineate the mission of the organisation and specify to management about the strategic methods. When Enron collapsed, the Sarbanes ACT was already enacted. It was also necessary for a company to adhere to the conflict of interest policy (Broni et al. 2017). Unethical practices of Enron led to conflict of interest. Malfunctioning in accounts department ruined the entire business infrastructure. It led to pessimistic corporate culture. The autocratic leadership in Enron shaped a negative behaviour of the employees that helped in the artwork of the f raud accounting. Analyse the opportunities and threats In the book of the managerial economy the supply is defined as amount of services and good that people sell in a given time at different prices, where other factors remain constant (Armstrong and Taylor 2014.). Enron was a leading business in terms of supply high quality energy. In North America and all over the Europe there was an increase in demand by the economies in need of energy. This gave new opportunities to Enron such as meeting new demands for clean energy. With the reduction of pollution being the main concern in US, Enron had bright opportunity with its franchise policy, innovative culture, online established market, technology and other assets to be a prime contributor of clean and renewable energy (Prebble 2016). The strengths of the company gave it an opportunity to open to merger or acquisition. Enron could use one or more strategy in this aspect to grow due to its experience of merger. According to Abdel-Khalik (2016), a business can go global by market penetration, development of new markets or capture a large portion of existing market by market saturation. If Enron would not have collapsed it had a golden opportunity to tap into the market of India and China using its many options such as joint ventures, franchising, acquisition and licensing. These two countries are emerging as big energy consumers and are in need of energy to keep their industries operational (McLean and Elkind 2013). Since, Enron failed due to unethical practices it is unable to experience the fierce competition by big companies in US that are ready to engulf a large share of the energy market. It is the treat to the company that the other threat includes the new regulation due to the greenhouse gas emission. The national and international regulation as a response to the global warming would have effected Enron in Europe for instance the Kyoto protocol (Markham 2015). There would have been decrease in the companys profit due to recession in economy and foreclosure. It would have also resulted in the decreased consumption of natural gas. The subprime mortgage caused the economic recession and mortgage delinquencies (Hosseini and Mahesh 2016). Terrorist attack on Enron line of business was another major threat that may have affected the initiatives and the investments. Remedial response of company and recommendations The remedial option for Enron was innovation in business expansion to different lines. Business merger and acquisition was other remedial option to prevent the profit decline and fraud practice in accounting. It used its assets for more investment in energy and natural gas transportation, which helped Enron to move towards paper and pulp business, develop energy trading markets and increase is business communications. Further, Enron tried to focus more on the growth strategies such as concentration and diversification. These strategies helped the company to have long term profits in all business lines. As per the literature evidence these strategies were all effective in having successful business (Friedman and Gerstein 2017). However, only due to unethical practice it was unsuccessful. The only strategy for preventing another Enron case is to conduct the business in an ethical manner using the exhaustible human capital and maintaining the innovative character. The board of directors should closely monitor the internal environment of organisation. There is a need of reforming the auditing system that will reduce the possibility of the financial disaster (Adams et al. 2017). Further, Auditors independence is required. It is the cornerstone of the capital market. There is a need for the auditors to objectively assess the accounting and financial statements of the publically traded company. It should not be hampered by the long term partnership established between auditors and firms. Auditors response is effective method and should be under scrutiny by the Public Companies Accounting Oversight Board, that was created by Sarbanes-Oxley Act. It will help reduce the conflict of interest. There is a need of government regulations and rules that needs to be updated on timel y basis and should not be relaxed and eliminated (McLean and Elkind 2013). Conclusion It can be concluded from the above discussion that Enron hit the financial world very drastically. The main cause of failure includes unethical leadership, dominating culture, inappropriate decision making-authority and poor management controls that led to faulty corporate governance structure. It was the biggest corporate bankruptcy. In future such scandal can be prevented by increased regulation and oversight. The only strategy for preventing another Enron case is to conduct the business in an ethical manner using the exhaustible human capital and maintaining the innovative character. There is a need of government regulations and rules that needs to be updated on timely basis and should not be relaxed and eliminated. References Abdel-Khalik, A.R., 2016. How Enron used Accounting for Prepaid Commodity Swaps to Delay Bankruptcy for One Decade: The Shadowy Relationships with Big Banks. Adams, T., Krishnan, J. and Krishnan, J., 2017. Client Influence and Auditor Independence Revisited: Evidence from Auditor Resignations. Alleyne, P., 2016. The influence of organisational commitment and corporate ethical values on non-public accountants whistle-blowing intentions in Barbados.Journal of Applied Accounting Research,17(2), pp.190-210. Armstrong, M. and Taylor, S., 2014.Armstrong's handbook of human resource management practice. Kogan Page Publishers. Breevaart, K., Bakker, A.B., Hetland, H. and Hetland, H., 2014. The influence of constructive and destructive leadership behaviors on follower burnout. InBurnout at work: A psychological perspective(pp. 102-121). Psychology Press, New York City. Broni, G., Velentzas, J. and Papapanagos, H., 2017. Marketing Ethics and Communication Strategy in the Case of Enron Fraud. InAdvances in Applied Economic Research(pp. 269-278). Springer, Cham. Dibra, R., 2016. Corporate Governance Failure: The Case Of Enron And Parmalat.European Scientific Journal,12(16). Friedman, H.H. and Gerstein, M., 2017. Leading with compassion: the key to changing the organizational culture and achieving success.Psychosociological Issues in Human Resource Management,5(1). Hosseini, S.B. and Mahesh, R., 2016. THE LESSON FROM ENRON CASE.Journal of Current Research,8(08), pp.37451-37460. Khan, C., 2017. Corporate Governance, Management Strategies and Social Responsiveness.Journal of Management Science, Operations Strategies (e ISSN 2456-9305),1(2), pp.1-6. Mariani, G., 2017.MA and Value Creation: A SWOT analysis. G Giappichelli Editore. Markham, J.W., 2015.A financial history of modern US corporate scandals: From Enron to reform. Routledge. McLean, B. and Elkind, P., 2013.The smartest guys in the room: The amazing rise and scandalous fall of Enron. Penguin. Meymandi, A.R., Rajabdoory, H. and Asoodeh, Z., 2015. The Reasons of Considering Ethics in Accounting Job.Economics,2(2), pp.136-143. Prebble, L., 2016.Enron. Bloomsbury Publishing. Shapiro, J.P. and Stefkovich, J.A., 2016.Ethical leadership and decision making in education: Applying theoretical perspectives to complex dilemmas. Routledge. Stahl, G.K., Miska, C., Noval, L.J. and Patock, V.J., 2016. IN publicized THE corporate WAKE scandals, OF A MAJOR ECONOMIC CRISIS and highly calls for more responsible corporate governance and leadership continue to grow (eg Pearce Stahl, 2015; Waldman Galvin, 2008). Ethical breaches have become front-page news, such as: Enron and Arthur Andersens questionable accounting practices, misuse of company funds at Merrill Lynch and Elf in France, the collapse of Lehman Brothers, improper payments to government officials by Xerox managers in India, Nikes use of ....Readings and Cases in International Human Resource Management, p.416. Tan, P. and Yeo, G., 2013. Accounting scandals and implications for directors: Lessons from enron. InEncyclopedia of Finance(pp. 495-499). Springer US.

Tutorial of Kinemtatics Essay Example

Tutorial of Kinemtatics Essay Applied Science Department (ASD) Centre for Foundation Studies and Extension Education (FOSEE) PPH 0095 Mechanics Foundation in Engineering ONLINE NOTES Chapter 2 Kinematics FOSEE , MULTIMEDIA UNIVERSITY (436821-T) MELAKA CAMPUS, JALAN AYER KEROH LAMA, 75450 MELAKA, MALAYSIA. Tel 606 252 3594 Fax 606 231 8799 URL: http://fosee. mmu. edu. my/~asd/ PPH0095 MECHANICS Contents 2. 0 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 2. 10 2. 11 2. 12 2. 3 Introduction Definitions of Linear Motion Distance Displacement Speed and Velocity Average Velocity Instantaneous Velocity Average Acceleration Instantaneous Acceleration Equations of Linear Motions Motion Graphs Free Falling Objects under gravity Projectile Motion Uniform Circular Motion ASD 2011/12 KINEMATICS 1/23 PPH0095 MECHANICS Mind Map ASD 2011/12 KINEMATICS 2/23 PPH0095 MECHANICS OBJECTIVES Upon completion of this chapter, you should be able to: 1) 2) 3) 4) 5) define distance, displacement, velocity, acceleration. know how to apply all the equation for linear motion with constant acceleration. raw graph velocity versus time , distance versus time and explain them. understand the concept of free fall and should be able to solve the problem. understand the concept of projectile motion and uniform circular motion and should be able to solve the problem. 2. 0 INTRODUCTION Kinematics is the branch of mechanics which studies the motion of objects without considering the forces that cause the motion. Vector quantities such as displacement, velocity, and acceleration are involved. The study of the motion of objects under the action of forces is called dynamics. The study of the motion of objects, and the related concepts of force and energy, form the field called mechanics. Mechanics is customarily divided into two parts i. e. kinematics and dynamics. †¢ Kinematics : the description of how objects move. Kinematics in one dimension : describing an object that moves along a straight line path, which is one dimensional motion. Kinematics in two dimensions : the description of the motion of objects that move in paths in two (or three) dimensions. †¢ Dynamics : deals with force and why objects move as they do. In this part we will solve the following questions : What akes an object at rest begin to move ? What causes a body to accelerate or decelerate ? What is involved when an object moves in a circle ? We can answer in each case that a FORCE is required. 2. 1 †¢ †¢ DEFINITIONS of LINEAR MOTION Linear motion is motion along a straight line. Three types of motion: †¢ Translational †¢ Rotational †¢ Vibrational A SD 2011/12 KINEMATICS 3/23 PPH0095 MECHANICS †¢ Figure 1 †¢ †¢ We only discuss objects that move without rotating (Figure 1a) Motion in straight line; †¢ Vertical †¢ Horizontal †¢ Slanting Reference Frames †¢ †¢ Any measurement of position, distance or speed must be made with respect to a frame of reference. We will write a custom essay sample on Tutorial of Kinemtatics specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Tutorial of Kinemtatics specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Tutorial of Kinemtatics specifically for you FOR ONLY $16.38 $13.9/page Hire Writer It is always important to specify the frame of reference when stating a speed. In everyday life, we usually mean with respect to the Earth. Position †¢ For one-dimensional motion, we often choose the x axis as the line along which the motion takes place. †¢ The position of an object at any moment is given by its x coordinate. †¢ If the motion is vertical, as for a dropped object, we usually use the y axis. 2. 2 †¢ †¢ †¢ DISTANCE The length of the actual path or total path length. It depends on the frame of reference, for example, Ipoh is 200 km away from Kuala Lumpur. A set of coordinate axes represents a frame of reference. ASD 2011/12 KINEMATICS 4/23 PPH0095 MECHANICS 2. 3 †¢ †¢ DISPLACEMENT The change in position of the object, i. e. displacement is how far the objects is from its starting point. For example : A change from an initial position xi to the final position xf, the displacement is, ? x = xf xi. The symbol ? (delta) means change in. So ? x means the change in x which is the displacement. It is a quantity that has both magnitude and direction and represented in diagrams by arrows. Example 1 : A person walking 70 m to the east and then turning around and walking back (west) a distance of 30 m. †¢ Total distance = 100 m Displacement = xf xi = 40 m 0 m = 40 m Figure 2 2. 4 †¢ †¢ †¢ †¢ SPEED and VELOCITY The most obvious aspect of the motion of a moving object is how fast it is moving, i. e. its speed or velocity. Speed is simply a positive number, (i. e. a scalar: having magnitude only) with units. Velocity, on the other hand, is used to signify both the magnitude (numerical value) of how fast an object is moving and also the direction in which it is moving. (velocity is therefore a vector). Average Speed is defined as the total distance travelled along its path divided by the time it takes to travel this distance, i. . average speed = distance travelled time elapsed ASD 2011/12 KINEMATICS 5/23 PPH0095 MECHANICS 2. 5 †¢ AVERAGE VELOCITY Average velocity is defined as the displacement divided by the elapsed time, i. e. average velocity, v ave = †¢ †¢ x f xi displacement ? x = = time elapsed ? t t f ti Average velocity would be zero if start ing and ending point are the same. Unit : ms-1 Figure 3: Velocity of a car as a function of time at constant velocity. Figure 4: Velocity of a car as a function of time with varying velocity. 2. 6 †¢ †¢ †¢ INSTANTANEOUS VELOCITY The instantaneous velocity is the velocity at any instant of time. In general the instantaneous velocity at any moment is defined as the average velocity over an infinitesimally short time interval. We define instantaneous velocity as the average velocity in the limit of ? t becoming extremely small, approaching zero. v = lim †¢ ?t > 0 ?x dx = ? t dt Let ? t approach zero, ? x approaches zero as well. But the ratio ? x/? t approaches some definite value, which is the instantaneous velocity at a given instant. KINEMATICS 6/23 ASD 2011/12 PPH0095 MECHANICS 2. 7 †¢ AVERAGE ACCELERATION Acceleration specifies how rapidly the velocity of an object is changing. Average acceleration is defined as the change in velocity divided by the time taken to make this change, i. e. v f vi change of velocity ? v average acceleration, aave = = = time elapsed ? t t f ti Unit : ms-2 †¢ 2. 8 †¢ INSTANTANEOUS ACCELERATION The instantaneous , a , is defined as the limiting value of the average acceleration as we let ? t approach zero. instantaneous acceleration, a = lim ? dx ? d? ? 2 dv ? dt ? = d x a = = dt dt dt 2 ?t > 0 ? v dv = ? t dt since v = †¢ dx , so dt Acceleration tells us how fast the velocity changes, whereas velocity tells us how fast the position changes. x v= dt and dv d 2 x a = = dt dt 2 2. 9 †¢ EQUATIONS of LINEAR MOTIONS Many practical situations occur in which the acceleration is constant, i. e. the acceleration doesnt change over time. We now treat this situation when the magnitude of the acceleration, a, is constant and the motion is in a straight line. In this case, the instantaneous and average acceleration are eq ual. To simplify our notation, let us take the initial time in any discussion to be zero the elapsed time, t initial velocity , vo the position at time t is s the velocity at time t is v †¢ ASD 2011/12 KINEMATICS 7/23 PPH0095 MECHANICS †¢ †¢ †¢ The acceleration, which is assumed constant in time , will be a = Multiply both sides by t and get: ? v = vo + at at = v ? vo v ? vo t †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. ( 1. 9. 1 ) [omit s] velocity vo v O time t †¢ ?v +v? s=? o ? t ? 2 ? †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦( 1. 9. 2 ) [omit a] †¢ Substitute equation (1. 9. 1) into (1. 9. 2), s =( v o + v o + at )t 2 or s = vot + ? at2 †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 3 ) [ omit v ] †¢ †¢ We now derive the fourth equation, which is useful in situations where the time, t is not known. From equation ( 1. 9. 1 ) , solve for t, obtaining t= v ? vo a .. †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 4 ) †¢ Substituting equation ( 1. . 4 ) into equation ( 1. 9. 3 ), we have ASD 2011/12 KINEMATICS 8/23 PPH0095 MECHANICS 2 2 ? v + v o v ? v o ? v ? v o s=? ?= 2a ? 2 a ? †¢ Solve for v 2 and obtain 2 v 2 = v o + 2as †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. ( 1. 9. 5 ) [ omit t ] †¢ From equation ( 1. 9. 1 ) , solve for vo, obtaining vo = v – at†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. (1. 9. 6) †¢ Substitute equation (1. 9. 6) into (1. 9. 2), s =( v + v ? at )t 2 or s = vt ? ? at2 †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 3 ) [ omit vo ] Example 2:: Spotting a police car, you brake a porsche from 75 km/h to 45 km/h over a displacement of 88 m. a) What is the acceleration assumed to be constant ? Given: vo = 75km / h = 75 ? 103 = 20. 83 m/s 3600 45 ? 103 v = 45km / h = = 12. 5 m/s 3600 s = 88 m, a = ? v 2 = vo + 2a s (12. 5 m/s)2 = (20. 83 m/s)2 + 2a(88 m) a = -1. 6 m/s1 2 b) What is the elapsed time ? s = ? (vo + v)t 88 m = ? (12. 5 m/s + 20. 83 m/s)t t = 5. 4 s c) If you continue to slow down with the acceleration calculated in (a), how much time will elapse in bringing the car to rest from 75 km/h ? v = vo + at 20. 83 m/s = 12. 5 m/s + (-1. 6 m/s2 )t t = 13 s ASD 2011/12 KINEMATICS 9/23 PPH0095 MECHANICS d) In ( c ) what distance will be covered ? s = vot + ? at2 = (20. 3 m/s)(13 s) + ? (-1. 6 m/s2)(13 s)2 = 137 m e) Suppose that later, using the acceleration calculate in (a) but a different initial velocity , you bring your car to rest after travelling 200 m . What is the total braking time ? s = vt ? ? at2 200 m = (0 m/s) t – ? (-1. 6 m/s2) t2 t = 16 s 2. 10 MOTION GRAPHS †¢ The motion of a body can be illustrated by o a displacement-time ( x t ) graph. o a velocity-time ( v ) graph o an acceleration-time ( a t ) graph Displacement-time graph or s t graph of a body shows how the displacement of the body varies with time. o Instantaneous velocity, v= †¢ dx = gradient of the s – t graph. dt Figure 5 shows the x – t graphs for four types of motion. Figure 5a o Constant velocity Velocity = gradient of the graph = constant ASD 2011/12 KINEMATICS 10/23 PPH0095 MECHANICS Figure 5b o Constant acceleration with initial velocity u = 0 When t = 0, gradient = 0 Gradient increases as t increases ? Velocity increases Figure 5c o Constant acceleration with initial velocity u ? 0 When t = 0, gradient ? 0 hence initial velocity ? 0 Gradient increases as t increases ? Velocity increases ASD 2011/12 KINEMATICS 11/23 PPH0095 MECHANICS Figure 5d †¢ Non-uniform acceleration When t = 0, gradient ? 0 Hence initial velocity ? 0 When t = t, gradient = 0 Hence velocity = 0 When t = t2, gradient ; 0, Hence velocity is negative. When vel ocity is negative, object is moving in the opposite direction. Velocity–time graph or v – t graph of a body shows how the velocity of a body varies with time. Velocity, v = dx dt Displacement, s = ? v dt = area under the v – t graph. Instantaneous acceleration, a = †¢ dv = gradient of the v t graph at that instant. dt Figure 6 shows the v – t graphs for six types of motion. ASD 2011/12 KINEMATICS 12/23 PPH0095 MECHANICS Figure 6a Uniform velocity Gradient = 0, acceleration = 0 Displacement from t = t1 to t = t2, s = shaded area , A Figure 6b o Uniform acceleration Initial velocity = 0 Gradient = constant, hence Acceleration = constant Displacement from t = t1 to t = t2, s = shaded area , A ASD 2011/12 KINEMATICS 13/23 PPH0095 MECHANICS Figure 6c o Uniform acceleration Initial velocity ? 0 Gradient = constant, hence Acceleration = constant Displacement from t = t1 to t = t2, s = shaded area , A Figure 6d o Uniform acceleration Initial velocity ? 0 Co nstant negative gradient implies constant negative acceleration (constant deceleration) ASD 2011/12 KINEMATICS 14/23 PPH0095 MECHANICS Figure 6e o Non-uniform velocity Initial velocity = 0 Gradient decreases, hence acceleration decreases, Displacement from t = t1 to t = t2, s = shaded area , A Figure 6f o Increasing acceleration Initial velocity = 0 Gradient increases, hence acceleration increases. †¢ Acceleration-time graph or a – t graph of a body shows how the acceleration of the body varies with time. dv a = dt Increase in velocity = ? a dt = area under the a – t graph. Figure 7 shows four acceleration–time graphs. †¢ ASD 2011/12 KINEMATICS 15/23 PPH0095 MECHANICS Figure 7a o Constant acceleration Gradient=constant Area, A = increase in velocity from t = t1 to t = t2 Figure 7b o Acceleration increases uniformly Gradient=constant Area, A = increase in velocity from t = t1 to t = t2 Figure 7c o Decreasing acceleration Area, A = decreasing in velocity from t = t1 to t = t2 ASD 2011/12 KINEMATICS 16/23 PPH0095 MECHANICS Figure 7d o Uniform velocity When velocity = constant, acceleration , a = 0 2. 11 FREE FALLING OBJECTS UNDER GRAVITY †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ Any object moving freely under the influence of gravity, regardless of its initial motion. When an object is in free fall, we assume that air resistance is negligible and that the only force acting on it is gravity. Object thrown upward/downward, will both experience the same acceleration as an object released from rest. Assuming air resistance is negligible, the rate of acceleration (g) of all objects in free fall is approximately 9. 8 m/s2. The vertical motion of a freely falling object is equivalent to motion in one dimension under constant acceleration. The equations for uniformly accelerated motion can be applied to free fall. Since the motion is vertical, y replaces x and y0 replaces x0 while g replaces the symbol a. It is arbitrary whether we choose y to be positive in the upward or downward direction; but we must be consistent about it throughout a problem’s solution. Thrown downward: a = g = +9. 80 m/s2 Thrown upward: a = g = -9. 80 m/s2 For example: When a ball is thrown vertically upwards, its velocity decreases as it rises because the acceleration of free fall is in the opposite direction to the motion. If the upward direction is assumed to be positive, then the acceleration a = 9. 8 m/s2. When the ball reaches the maximum height, o The velocity v = 0, and o The acceleration a = -9. 0 m/s2 Figure 8 shows the graphs for the motion of the ball. †¢ ASD 2011/12 KINEMATICS 17/23 PPH0095 MECHANICS Figure 8 †¢ Equations for free-fall acceleration: o v = v o + gt o y = (v + v o )t o y = vo t + gt 2 o y = vt 1 gt 2 2 1 2 1 2 o v = v o + 2gy 2 Example 3: A boy on a bridge throws a stone vertically downward toward the river below with an initial velocity of 14. 7 m/s . If the stone hits the water 2. 00 s later, what is the height of the bridge above the water? Solution: Take y as positive downward Given: v0 = 14. 7 m/s , ( downward) , t = 2. 00 s and g = + 9. 8 m/s/s 1 y y o = v o t + at 2 2 = (14. )(2. 00) + (1 / 2)(9. 8)(2. 00) 2 = 29. 4 + 19. 60 y = 49. 0 m 2. 12 PROJECTILE MOTION †¢ †¢ It is the motion in two dimensions under the action of gravity only (downward) We Can study the motion of a projectile by considering ASD 2011/12 KINEMATICS 18/23 PPH0095 MECHANICS †¢ †¢ o The vertical component. And o The horizontal component of the motion. The vertical component of motion is motion under uniform acceleration. The horizontal component of motion is motion under uniform velocity If air resistance is negligible, then the horizontal component of motion does not change; thus ax = 0 and vx = vx0 = constant. The vertical component of motion is affected by gravity and is described by the equations for an object in free fall. To describe it, choose a suitable origin, O and the axes (Figure 9). Let vo denote the initial velocity and ? the angle between vo and the positive x-axis. †¢ Figure 9 †¢ From diagram, the motion can divide in two components, horizontal (x-axis) and vertical (y-axis). Two assumptions: o The free-fall acceleration, g is constant over the range of the motion and is directed downward. (-g) o The effect of air resistance is negligible that is the horizontal motion has zero acceleration. x-component 0 vxo = vocos? 0 = 0 vx x y-component -g vyo = vosin? yo = 0 vy y Acceleration Initial velocity Initial position Velocity Position ASD 2011/12 KINEMATICS 19/23 PPH0095 MECHANICS From this, one can show that: Vertical component (y-component): Vertical velocity component: v y = v yo gt = v o sin ? gt Vertical position component: 1 1 y = v yo t gt 2 = (v o sin ? )t g t 2 2 2 *from v = vo + at *from y = v o t + 1 2 at 2 †¢ At maximum Height, H, the vy = 0. 2 From, v = vo + 2a y 2 0 = (v o sin ? ) 2 ? 2 gH H= v0 sin 2 ? 2g 2 If T is the time taken from O to A, to find the T, y = 0, t = T From, y = v o t + 1 2 at 2 1 gT 2 2 0 = (v o sin ? T ? T = 2v o sin ? g Horizontal component (y-component): Horizontal velocity component : vx = vxo = vo cos ? Horizontal position component : x = vxot = (vo cos ? )t To find the horizontal Range, R, t = T, x = R ASD 2011/12 KINEMATICS 20/23 PPH0095 MECHANICS From x = vo t + 1 2 at ,a =0 2 ? 2v sin ? ? ? R = (v o cos ? )? o ? ? g ? ? R= v o sin 2? g The maximum horizontal range is achieved when ? = 45o. At any time the distance, r of the projectile from the origin is r = x 2 + y2 By eliminate, the trajectory (the relation between x and y) is a parabola, Vertical position component : y = (v o sin ? )t †¢ 1 2 gt 2 Horizontal position component : x = (vo cos ? ) t x t = v o cos ? ? x ? 1 ? x ? y = (vo sin ? )? ? v cos ? ? ? 2 g ? v cos ? ? ? ? ? ? o ? ? o ? g x2 = (tan ? )x ? 2 2 2vo cos ? = x tan ? ? gx 2 sec 2 ? 2 2v 2 gx 2 y = x tan ? ? 2 (1 + tan 2 ? ) 2v ASD 2011/12 KINEMATICS 21/23 PPH0095 MECHANICS †¢ Since sin 2? = sin (180o 2? ), there would be two angles of projection, ? and (90o- ? ), that would achieve a particular range R for a certain speed of projection vo . For the speed of projection vo , however, the maximum range is obtained only when the angle of projection is 45o as shown in Figure 10. Figure 10 2. 13 UNIFORM CIRCULAR MOTION An object that moves in a circle at constant speed is said to experience uniform circular motion where the magnitude of velocity remains constant the direction of velocity continuously change †¢ Acceleration is defined as the rate of change of velocity. The rate of change of velocity depends on the change in direction as well as the change in the magnitude. Therefore, object revolving in a circle is continuously accelerating (even when the speed remains constant). An object moving in a circle of radius r with constant speed v, has an acceleration whose direction is toward the center of the circle and whose magnitude is given by the formula 2 †¢ aR = (Please refer to text book section 5. 2, pages 120, how to get this equation) v r ASD 2011/12 KINEMATICS 22/23 PPH0095 MECHANICS v1 aR aR v1 Figure 11 †¢ †¢ †¢ The acceleration vector always points toward the center of the circle. The velocity vector always points in the direction of motion (tangent to the circle or perpendicular to the radius of the circle). Circular motion is often described in terms of the frequency f as so many revolutions per second. The period T of an object revolving in a circle is the time required for one complete revolution. T= 1 f v= 2? r T END OF CHAPTER 2. ASD 2011/12 KINEMATICS 23/23