The Law of Demand and Demand Factors

Introduction People often exercise choice because human wants are infinite while the resources available are scarce. For the satisfaction of human wants to occur, there must be a relationship between the production of commodities and their corresponding pricing system. In the market, the forces of demand and supply determine the prices of goods and services.Advertising We will write a custom essay sample on The Law of Demand and Demand Factors specifically for you for only $16.05 $11/page Learn More At the same time, the prices of goods and services affects demand and supply (Suri, 2011). In ordinary terms, demand refers to desire or urge of purchasing commodities. In economic terms however, demand is something beyond a plain desire. Demand in this sense represents a want supported by the power or capability to purchase. The Law of demand The law of demand asserts that all other factors kept constant, the price and quantity demanded are inversely proport ional. For instance, a company selling snacks may sell approximately 100,000 cookies at $1 each. If the company decreases the price of its cookies to $0.75 each, the number of cookies sold may increase to 115,000. On the other hand, if the company decides to increase the price per cookies to $1.25, the number of cookies sold may reduce to approximately 85,000. This can only apply when all other factors like customer preference are constant (Saint-Leger, 2011). In this regard, there are various assumptions made in relation to the law of demand for the establishment of the price-demand relationship. These assumptions include assuming that the income of consumers does not change, there are no changes in preferences and tastes of consumers, prices of other goods remain constant and there are no changes in the size and composition of the consumer population (Akrani, 2009). A demand curve clearly represents the effect of price on the quantity of goods and services demanded. In the demand curve, the quantity demanded lies on the horizontal axis while the price lies on the vertical axis. Any change in the price causes a shift along the demand curve. However, there are other factors that can cause a shift in the demand curve other than price. These may include price alterations for complement goods, consumer demand for alternate goods and customer preferences (Saint-Leger, 2011). Even though it is evident that quantity demanded changes as price of commodities changes, such a change varies from commodity to commodity. This means that the amount of change is not constant for all commodities.Advertising Looking for essay on business economics? Let's see if we can help you! Get your first paper with 15% OFF Learn More In this case, some goods and services respond more to changes in price while others respond less. Elasticity of demand explains the extent of the responsiveness of quantity demanded in relation to changes in price. This means that the elasticit y of demand explains further the relationship of price and demand (Akrani, 2009). Factors affecting the demand of commodities There are various factors that affect the demand of goods and services. The major factor is price of goods and services. In most cases, the quantity of a product purchased by a customer depends on the price of that particular commodity. In this case, people are less willing to purchase a commodity when the price of such a commodity increases. On the other hand, customers will purchase a certain commodity in large volumes if the price of the commodity reduces (Sothern, 2011). Another factor that influences the demand of commodities is of the size of the income of customers. In general, consumers will buy more when their income increases and buy less when their income reduces. As the income of some people increase, their consumption increase causing an increase in the demand for various commodities. For the goods which are superior and of good quality, the incr ease in income causes increase in their demand. On the other hand, demand for inferior goods reduces with increase in income levels (Suri, 2011). The number of buyers at a specific time also influences the demand for goods and services. For instance, the demand for stationery increases during the periods when the schools are opening. In addition, there is an increased demand for clothes and playing dolls for children during the holidays especially the Christmas period. The demand for these goods however reduces when the holidays are over (Sothern, 2011). The black Friday is a very important day in America, which influences the demand for commodities. Economists site this day as the most important day of the year for the economy of United States. During this day, Americans flock in the shopping malls to purchase items and commodities for the Christmas celebrations. During this time, the demand for various commodities like electronics, children playing items and clothes increase heavi ly. In addition, most traders reduce the prices of some commodities during this day causing the demand to increase further. According a survey by the National Retail Federation (NRF), some 152 million people purchase heavily discounted commodities during this day (Washington, 2011). Conclusion The law of demand is an important concept in economics. It explains the relationship between the quantity of goods and services demanded and other factors including price, preferences, income and number of buyers. Business owners and companies should take time to understand the law of demand and comprehend the various factors that may increase demand for their products.Advertising We will write a custom essay sample on The Law of Demand and Demand Factors specifically for you for only $16.05 $11/page Learn More This will help them to maximize their sales since they will perfectly understand the market during specific periods. The understanding of the law of demand is also useful in determining the quantity of supply needed for a particular commodity. References Akrani, G. (2009). Demand in Economics: Law of Demand and Elasticity of Demand. Web. Saint-Leger, R. (2011). The Determinants of Demand That Will Shift the Demand Curve. Web. Sothern, M. (2011). What Are the Factors Affecting Demand Economics?  Web. Suri, S. (2011). Seven Factors that influences the Demand for a Commodity. Web. Washington, J. S. (2011). Black Friday: Most important day of the year for the US economy. Web. This essay on The Law of Demand and Demand Factors was written and submitted by user Frankl1nSt0rm to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

Of Mice and Men Animal Imagery Essays

Of Mice and Men Animal Imagery Essays Of Mice and Men Animal Imagery Paper Of Mice and Men Animal Imagery Paper Essay Topic: Of Mice and Men In the novel, Of Mice and Men, Steinbeck uses comparisons between animals and humans to demonstrate Lennie’s animalistic qualities. Steinbeck compares Lennie to animals to illustrate his innocence, immaturity, unawareness, and curiosity. Animal imagery is used to provide insight to the characters personalities and behaviors through the comparison between Lennie and a bear, his obsession with rabbits, and his similarities to Candy’s dog. Throughout the novel, Steinbeck compares Lennie’s natures and habits to that of a bear. At the beginning of the novel, Lennie’s gait is described as similar to the way a bear drags his paws (2). The word â€Å"drags† hints a sense of relaxation and calmness which is evident in Lennie’s personality. Lennie is not concerned with the trivial matters that consume the other characters. As Lennie bends down to get water from the pond, he dabbles his big paw in the water and wiggles his fingers to make circles(3). â€Å"Dabbles† illustrates the delicacy in his movement and shows his unawareness to his immense, bearlike size. Lennie is not worried about anything except how the water ripples. He remains unaffected by the everyday struggles of the majority of people in this time period. The comparison between Lennie and a bear show his unusual and immense size, but also the curious and careful nature of his personality. Lennie’s obsession with rabbits shows his immature and innocent personality. After Lennie kills one of the pups, he is extremely concerned with the fact that George might not allow him to tend the rabbits anymore(85). Lennie’s immaturity is portrayed by his inability to realize the full extent of what he has done. Before George shoots Lennie, Lennie makes sure that he will still assume the position as the rabbit tender(105). This is another example of how Lennie’s immaturity is illustrated. Although Lennie just killed Curley’s wife, he is only concerned with the rabbits. Lennie’s love of rabbits is a clear example of his immaturity and innocence. Candy’s relationship with his dog is similar to George and Lennie’s connection. Candy tells Slim â€Å"He doesn’t mind taking care of his dog,† but Slim agrees he needs to be shot(45). Lennie and Candy’s dog both were unable to escape death, and Slim agrees in both situations that it is for the better. Towards the end of the dog’s life, Carlson explained to Candy that â€Å"he’d shoot the dog right in the back of the head. He wouldn’t feel it†(45). After George shoots Lennie, Curley points out â€Å"right in the back of the head†(107). George shot Lennie himself so Lennie would not be afraid. Neither the dog or Lennie saw it coming, nor were they aware that their lives were about to end. The comparison between Candy’s dog and Lennie illustrate Lennie’s innocence and his unawareness of what he had done. Animal imagery is used throughout the novel to show the comparison between Lennie’s personalities to that of an animal. Each animal demonstrates a different behavior of Lennie’s. The bear shows his curiosity, the rabbits show his innocence and immaturity, and the dog shows his unawareness.

5 Ways to Stay Focused and Stop Procrastinating

5 Ways to Stay Focused and Stop Procrastinating Procrastination, whether at work or home, is common to human nature. Sometimes, it might be procrastinating about small things such as taking your favorite suit to the dry cleaners. Sometimes, it may be something more important such as being late to turn a report in at work. There are tips that might help you to alter your mindset and remain focused. In the end, these small changes can break your procrastination habit as you find yourself getting much more accomplished.   Looking at the Big PictureWhen faced with a large project, it is sometimes simpler to break it up into sections so you can focus on one part at a time. By doing this, the task seems less overwhelming. Start with the hardest part first, and the rest will be easier to complete.  Set a Personal DeadlineMaybe you actually do have an office or home deadline to meet. For example, that big project for your boss is due on a certain date. At home, maybe your child needs help with a science project. By setting your own pe rsonal deadline ahead of the actual due dates, you will not be rushed to finish the project. Gather things together first, keep it organized and set yourself a schedule to do the work.  Schedule Your TimeTo avoid being overwhelmed, you can schedule ten-minute breaks each hour. It gives you time to get something to drink, stretch your legs a bit and collect your thoughts. Write down what you want to accomplish each day and stick to the schedule. Once you are able to see the progress you are making, you’ll be encouraged to keep going. Eventually, you may no longer need those short breaks.  Remove DistractionsIt can be difficult to keep your mind on what you are doing when you are faced with distractions. When you work at a part-time computer job, the Internet is a big distraction. You have to learn to ignore it, and save the Internet for when you have reached your goal for the day. Your mobile phone letting you know that you have messages or calls is one of them. Place your cell phone a few feet away or, better yet, in another room while working and try to resist the temptation to pick it up. An extended texting session or repeated phone calls can eat up your work time.  Plan Ahead for the DayYou’ve been working for a while and get the munchies. Trips to the pantry for a snack can cut into your productivity, especially since that trip to the kitchen can take several minutes. It might be a good idea to prepare snacks for the following day, and place them beside you while you work.  Procrastinating can keep you from finding that ideal job, but TheJobNetwork can do the job searching for you, which leaves your time free to do other things. By entering your job interests and qualifications, you will receive matches for jobs as soon as those jobs become available. TheJobNetwork works around the clock to see that you don’t miss any opportunities to find a great position. All you have to do is enter the types of jobs you are interested in, a nd list your qualifications to get alerts when jobs pop up.When you sign up for job match alert you won’t miss any opportunities.

Management must strive for efficiency & effectiveness throughout Essay - 2

Management must strive for efficiency & effectiveness throughout organisation. Discuss, relating to strategic and operational theories and concepts covered within the lecture notes of this course - Essay Example re the intrinsic management attributes that are linked with efficiency and effectiveness that is rampant in any organization in the time and age of today. The same are discussed in line with the strategic and operational theories and concepts that have been studied thus far. Strategic basis of the management regimes indicate that an organization is more than willing to think long term, and hence devise ways and means through which success would be envisioned for the sake of the business concern. The operational theories and concepts are also important to discern and later on comprehend because embody the basis of success for an organization in the long run. The manner in which the external environment plays a definitive role as well as the building up of the strategic. Similarly managing the marketing mix is pivotal towards resolving the management related problems on a proactive basis. The same is necessary because it helps solve quite a few issues which basically mar the basis of an organization in the long run (Sims 2002). Efficiency and effectiveness within an organization is achieved through hard work and consistency that is related with the different processes, activities and tasks. The strategy development process could either be an intended one within an organization or it could comprise of an emergent form. Both have challenges and implications which are related with the strategic drift, the learning organizational basis, the uncertain and complex conditions and the overall management of the strategy development processes. The strategic management is therefore a combination of the external environment and the strategic capability that holds the strategic choices like business level strategies, the corporate and international level strategies and the development directions and methodologies (Ruhli 1993). The external environment similarly is related with the building up of the strategic capabilities. This means that the internal level analysis holds

Is extreme obedience necessary for society Essay

Is extreme obedience necessary for society - Essay Example Extreme obedience leads to compliance of social norms in society. It ensures that people follow the set rules in society, thus promoting law and order in the society. Such obedience makes it easy for authority bodies to exert laws, which promote co-existence in the society. The obedience also makes it possible to establish hierarchies in organizations as there must be people at the top of an organization, as well as subordinates for organizations to function effectively. The Milgrim experiment provides a case that depicts compliance to extreme obedience. The experiment involved a research aimed at studying the effects of punishment on learning. The subjects of the experiment were given the role of a teacher, and were meant to make another subject learn a list of word pairs (McLeod, 1). They were then to give the learner an electric shock, and increase the shock level every time the learner made a mistake. Two thirds of the teachers used in the experiment administered the highest level of the electric shock, despite the learner complaining of pain. This experiment showed that authority figures have capacity to exert extreme obedience on their subjects. The teachers were commanded by an authority to administer high levels of pain, and most of them acted in response to the commands, thus administering the highest level of the electric shock. However, one third of the research subjects did not administer the highest level of the electric shock, which means that not everybody follows the given orders strictly. The Zimbardo jail role-play involved the use of students to play the role of prisoners and guards (Zimbardo 1). Those who took up the role of guards acted in extreme brutality, while those in the role of prisoners acted in complete obedience to the guards. This showed that people, and in this case the prisoners tend to obey orders given by authority figures. Extreme obedience helps in ensuring that rules are

Struggling for their lives Essay Example for Free

Struggling for their lives Essay Having read Mairs’ â€Å"On Being a Cripple,† it can be noted that Bogan’s epigraph is found to be perfectly appropriate. It is plain that the epigraph introduces the possibility of an escape from an implied predicament, which in this narrative, happens to be the author’s condition which she openly acknowledges as she writes â€Å"I am a cripple. I choose this word to name me† (Mairs, 159). However, it remains as a mere idea, something to be entertained. The first statement which defines that freedom from a burden can easily be devised. The confinement or the burden may be clear-cut and tangible as the author’s physical disability; the escape, however, can come in the form of a cure, an outlook, or geographical relocation. Initially, this reader is given to think that perhaps the easiest escape is to run away from everything and wish fervently that an intangible confinement will not follow you, to shed problems by simply changing the address. That’s understandably a very basic, human preconception. It sometimes works. But more often than it does, it may be best to stay dismal, especially if what you are running from is a condition or an issue unbound by territory. It could also mean withdrawing from people you see everyday, shutting out family, your spouse, as a defense mechanism to avoid being hurt as recounted by Mairs: Most twenty-two- and nineteen-year-olds, like George and me, can vow in clear conscience, after a childhood of chicken pox and summer colds, to keep one another in sickness and in health so long as they both shall live. Not many are equipped for catastrophe: the dismay, the depression, the extra work, the boredom that a degenerative disease can insinuate into a relationship. And our society, with its emphasis on fun and its association of fun with physical performance, offers little encouragement for a whole spouse to stay with a crippled partner. (p. 163) Another type of escape that is next entertained is any meansof cure. As Mairs complains on page 164, â€Å"because I hate being crippled, I sometimes hate myself for being a cripple. † This being the case, it is not uncommon for people to go to great lengths only to be disappointed. We are led to believe that this is a way for us to escape just the same – escape death, that is. For most people, it is nothing to spend a fortune just to have a family remain a vegetable until the end. That kind of escape is nothing compared to the atrocity of dying! And there are few who would even consider â€Å"death as more an escape† – from pain, humilitation, wasting away without event (Mairs, 166). It appears that anything is so much better than the current situation, and the cost of an escape is miniscule. As often is the case, a change of outlook is usually opted as the last resort, without knowing that it is by far the most enlightening solution that can even defy location and medicine. This reader would definitely agree that a positive outlook – and a good sense of humor – is the best escape, if it could ever be considered as one. On the contrary, it is more a resignation from the aggressive attempts at escaping. On one’s sense of humor, Mairs remarks that it is â€Å"the easiest to lose and the hardest to survive without† (Mairs, 160). That may be, but it can also be easily revived once we stop feeling sorry for ourselves. Once we free ourselves by taking stock of what we still have instead of grumbling about our losses, it will begin to dawn that it is searching and spending nothing on an escape actually is nothing compared to letting go of the burden. As Mairs writes, Months and even years went by without catastrophe, and really I was awfully busy. And I hadnt the time, let alone the inclination, to devote myself to being a disease. (p. 167) Finally, the epigraph drives the nail home about how the author approached the conflict of her narrative, which is centrally based on experience. It provides the reader a hunch as to how a solution or a particular transition can be offered and accepted and finally be applied. As Mairs writes her response to â€Å"the cosmic deal† beautifully, she declares that â€Å"I might as well do the job myself. Now that Im getting the hang of it† (Mairs, 168). It is a fine denuoement, which marks a closure defined by a wonderful sense of being. Work Cited Mairs, Nancy. â€Å"On being a cripple. † The Search for Self and Personal Values.

Molecular Aspects of Biofilm Essay -- Biology, Cluster of Cells

Almost all bacteria are known to have certain stage of life where they live in form of biofilms. A biofilm is nothing but cluster of cells embedded within a self-produced polymeric matrix and adherent to a living or inert surface (Costerton et al, 1995). Development of biofilm begins with the attachment of planktonic bacteria to a surface, initially through weak and reversible Van der Waals forces and then anchors itself irreversibly by cell adhesion structures such as pili. The primary colonizers facilitate the arrival of other cells by producing polymeric adhesion matrix that also holds the biofilm together (Costerton et al, 1995). In course of colonization and maturation of biofilm, cells communicate via quorum sensing which also leads to phenotypic and genotypic changes in cells (Diggle et al, 2007). This development of biofilm confers bacterial cells higher antibiotic resistant and immunity to environmental insults. Enhanced antibiotic resistance due to biofilm development impo ses increasing concerns in antimicrobial therapy, especially when it comes to biomedical devices associated infections (Donlan, 2001). According to an estimate, contamination of surgical instruments by biofilm increases approximately 1.6 billion dollars in hospital expenditures annually in United States of America (Gupta et al, 2002). Biofilms not only cause nuisance in clinical aspects but they also create a number of serious problems in industrial operations like in fluid processing operations, mechanical blockages, impedance of heat transfer process, and biodeterioration of components of metallic and polymeric systems that results in loss of billions of rupees each year (Rao et al, 1993 and 2009; Fleming, 2002; Boffardi, 2005). Pseudomonas aerugi... ...s censored i.e. some part of sample may lost before the final outcome is speculated or speculation itself is incomplete (Kaplan & Meier, 1958). In KM survival plot, survival probability is measured after certain time periods and between two sampling time points survival probability is assumed to be constant so as an outcome we speculate a series of horizontals steps of survival probability over a period of time (Bland & Altman, 1998). Survival probability was calculated as P=Nt/N. Where P is survival probability, N0 is initial number of cells, Nt is number of viable cells after giving biocide doses at t time. Standard error in P was calculated as SE=√[P(1-p)/N] The upper and lower limit of 95% confidence interval were calculated as =PÂ ±1.96*SE. The upper limit of probability of survival of cells at different doses were taken into account for plotting the graph. Molecular Aspects of Biofilm Essay -- Biology, Cluster of Cells Almost all bacteria are known to have certain stage of life where they live in form of biofilms. A biofilm is nothing but cluster of cells embedded within a self-produced polymeric matrix and adherent to a living or inert surface (Costerton et al, 1995). Development of biofilm begins with the attachment of planktonic bacteria to a surface, initially through weak and reversible Van der Waals forces and then anchors itself irreversibly by cell adhesion structures such as pili. The primary colonizers facilitate the arrival of other cells by producing polymeric adhesion matrix that also holds the biofilm together (Costerton et al, 1995). In course of colonization and maturation of biofilm, cells communicate via quorum sensing which also leads to phenotypic and genotypic changes in cells (Diggle et al, 2007). This development of biofilm confers bacterial cells higher antibiotic resistant and immunity to environmental insults. Enhanced antibiotic resistance due to biofilm development impo ses increasing concerns in antimicrobial therapy, especially when it comes to biomedical devices associated infections (Donlan, 2001). According to an estimate, contamination of surgical instruments by biofilm increases approximately 1.6 billion dollars in hospital expenditures annually in United States of America (Gupta et al, 2002). Biofilms not only cause nuisance in clinical aspects but they also create a number of serious problems in industrial operations like in fluid processing operations, mechanical blockages, impedance of heat transfer process, and biodeterioration of components of metallic and polymeric systems that results in loss of billions of rupees each year (Rao et al, 1993 and 2009; Fleming, 2002; Boffardi, 2005). Pseudomonas aerugi... ...s censored i.e. some part of sample may lost before the final outcome is speculated or speculation itself is incomplete (Kaplan & Meier, 1958). In KM survival plot, survival probability is measured after certain time periods and between two sampling time points survival probability is assumed to be constant so as an outcome we speculate a series of horizontals steps of survival probability over a period of time (Bland & Altman, 1998). Survival probability was calculated as P=Nt/N. Where P is survival probability, N0 is initial number of cells, Nt is number of viable cells after giving biocide doses at t time. Standard error in P was calculated as SE=√[P(1-p)/N] The upper and lower limit of 95% confidence interval were calculated as =PÂ ±1.96*SE. The upper limit of probability of survival of cells at different doses were taken into account for plotting the graph.

Physics Study Notes Hsc

Physics Summary Contents Core Topic One: Space 1. 2. 3. 4. Gravity Space Launch and Return Future Space Travel Special Relativity 2 3 13 14 Page Core Topic Two: Motors and Generators 1. 2. 3. 4. 5. The Motor Effect Electromagnetic Induction Electric Generators Transformers Electric Motors 19 24 27 29 31 Core Topic Three: From Ideas to Implementation 1. 2. 3. 4. Cathode Rays Quantum Theory Solid State Devices Superconductivity 32 37 43 48 Option Topic: Quanta to Quarks 1. . 3. 4. 5. 6. Models of the Atom Quantum Physics The Electron Microscope Applications of Radioactivity Nuclear Applications The Structure of Matter 53 57 59 61 66 67 William Kim HSC Physics Summary | page 1 Core Topic One: Space 1. The Earth has a gravitational field that exerts a force on objects both on it and around it  § Define weight as the force on an object due to a gravitational field The weight of an object is the force of gravity acting on it. r W = mg Where W is the weight in newtons (N), m is the mass i n kilograms (kg) and g can be either: 1. The acceleration due to gravity (= 9. 8 m/s/s at the Earth’s surface); or 2. The gravitational field strength (= 9. 8 N/kg at the Earth’s surface).  § Define gravitational potential energy as the work done to move an object from a very large distance away to a point in a gravitational field. As we lift an object from the ground to a height above the ground we do work on it. This work is stored in the object as gravitational potential energy.For an object of mass m at a height h above the Earth’s surface the gravitational potential energy E is given by: E p = mgh However this equation is valid only when the object is near the Earth’s surface. The gravitational potential energy is a measure of the work done in moving an object from infinity to a point in the field. The general expression for the gravitational potential energy of an object of mass m at a distance r from the centre of the Earth (or other planet) is g iven by: E p = ? G mM E r Newton’s Law of Universal Gravitation m F = G 12 2 r where G is the universal gravitational constant. The Gravitational Field Surrounding any object with mass is a gravitational field. g= Gm r2 Where M is the mass of the Earth (or other planet). Change in Gravitational Potential Energy The change in potential energy of a mass m1 as it moves from infinity to a distance r from a source of a gravitational field (due to a mass m2) is given by: mm ? E p = G 1 2 r Change in Gravitational Potential Energy Near the Earth (when radius increases from A to B) ?1 1? ?E p = GmM E ? ? ? ?r ? ? A rB ? William Kim HSC Physics Summary | page 2 . Many factors have to be taken into account to achieve a successful rocket launch, maintain a stable orbit and return to Earth  § Describe the trajectory of an object undergoing projectile motion within the Earth’s gravitational field in terms of horizontal and vertical components Any moving object that moves only und er the force of gravity is a projectile. The horizontal motion of a projectile is independent to the vertical motion. The reason for this result is that gravity is the only force acting on the objects and this always acts towards the centre of the Earth.Projectile motion can be analysed by realising that: 1. The horizontal motion is constant velocity. 2. The vertical motion of constant acceleration (with acceleration of g). Equations of Uniformly Accelerated Motion r r r v = u + at r r 1r s = ut + at 2 2 2 2 v = u + 2 as The Path of a Projectile The velocity at any point of the path of a projectile is simply the vector sum of the horizontal and vertical velocity components at that point. ?y = k (? x ) 2 ? ag ? k =? 2 ? ? 2u ? ? x? The horizontal component is constant.The vertical component changes at g, the acceleration due to gravity. Trajectories The path followed by a projectile – its trajectory – is a parabola (or linear) (1) Horizontal motion: ? x = u x t 1 (2) Ve rtical motion: ? y = a g t 2 2 From (1): ? x t= ux Combining (2) & (3): 1 ? ?x ? 1 ag ? y = a g ? ? = (? x )2 2 ? u ? 2 ? x? 2 ux 2 ux ? y ? x William Kim HSC Physics Summary | page 3  § Describe Galileo’s analysis of projectile motion Galileo was responsible for deducing the parabolic shape of the trajectory of a projectile.Galileo’s analysis of projectile motion led him to consider reference frames. These are what all measurements are compared to. The concept of Galilean relativity refers that the laws of mechanics are the same in a frame of reference that is at rest or one that moves with constant velocity.  § Explain the concept of escape velocity in terms of the: o gravitational constant o mass and radius of the planet If an object is projected upward with a large enough velocity it can escape the gravitational pull of the Earth (or other planet) and go into space.The necessary velocity to leave the Earth (or other planet) is called the escape velocity. Escape velocity depends on the gravitational constant, the mass and radius of the planet. Suppose an object of mass m is projected vertically upward from the Earth’s surface (mass of M and radius R) with an initial velocity u. The initial mechanical energy, that is, kinetic and potential energy is given by: E k i + E pi = 1 M m mu 2 ? G E 2 RE Let us assume that the initial speed is just enough so that the object reaches infinity with zero velocity.The value of the initial velocity for which this occurs is the escape velocity ve . When the object is at infinity the mechanical energy is zero (the kinetic energy is zero since the velocity is zero and the potential energy is zero because this is where we selected the zero of potential energy). Hence 1 M m mve2 ? G E = 0 which leads to: 2 RE ve = 2GM E RE William Kim HSC Physics Summary | page 4  § Discuss Newton’s analysis of escape velocity Circular Motion The motion of an object in a circular path with constant speed is cal led uniform circular motion.Although the speed remains the same in uniform circular motion, it follows that an object travelling in a circular path must be accelerating, since the velocity (that is, the speed in a given direction) is continually changing. r r v1 ? v2 v1 = v 2 r v2 r The change in velocity is given by: v2 r r r r v1 ? v = v 2 ? v1 r ? v1 r r ? v r and since: a = ? v r ? t ? v it follows that the object is accelerating. Isaac Newton proposed the idea of artificial satellites of the Earth. He considered how a projectile could be launched horizontally from the top of a high mountain so that it would not fall to Earth.As the launch velocity was increased, the distance that the object would travel before hitting the Earth would increase until such a time that the velocity would be sufficient to put the object into orbit around the Earth. (A higher velocity would lead to the object escaping from the Earth. ) Centripetal Acceleration As can be seen, when the change in veloc ity is placed in the average position between v1 and v2, it is directed towards the centre of the circle. When an object is moving with uniform circular motion, the acceleration (the centripetal acceleration) is directed towards the centre of the circle.For an object moving in a circle of radius r with an orbital velocity of v, the centripetal acceleration a is given by: v2 ac = r Earth Orbits A satellite can be put into Earth orbit by lifting it to a sufficient height and then giving it the required horizontal velocity so that it does not fall back to Earth. For the satellite to circle the Earth, the centripetal force required is provided by the gravitational attraction between the satellite and the Earth. Hence the centripetal acceleration is given by: v2 g= R William Kim HSC Physics Summary | page 5  §Use the term ‘g forces’ to explain the forces acting on an astronaut during launch g-forces on Astronauts Humans can withstand 4g without undue concern. Accelerations up to ~10g are tolerable for short times when the acceleration is directed parallel to a line drawn between the person’s front and back. The human body is relatively unaffected by high speeds. Changes in speed, however, that is, accelerations, can and do affect the human body creating ‘acceleration stress’. g-forces Acceleration forces – g-forces – are measured in units of gravitational acceleration g.For example, a force of 5g is equivalent to acceleration five times the acceleration due to gravity. If the accelerations are along the body’s long axis then two distinct effects are possible: 1. If the acceleration is in the direction of the person’s head they may experience a ‘black out’ as the blood rushes to their feet; or 2. If the acceleration is towards their feet, they may experience a ‘red out’ where the blood rushes to their head and retina.  § Compare the forces acting on an astronaut during launch with what happens during a roller coaster rideAs you ‘fall’ from a height, you experience negative g-forces (you feel lighter). When you ‘pull out’ of a dip after a hill or follow an ‘inside loop’, you experience positive g-forces (you feel heavier). The positive g-forces are like those astronauts experience at lift-off. Consider a rider in a car at the bottom of an inside loop. The rider has two forces acting on them: 1. Their normal weight (mg) acting down; and 2. The ‘normal reaction force’ (N) acting up. This is the push of the seat upwards on their bottom.Assume that the loop is part of a circle of radius R. A centripetal force is required for the rider to travel in a circle. This is the difference between the normal force and the weight force, that is: mv 2 mv 2 N ? mg = : N = mg + R R The g-forces are found from the ‘normal force’ divided by the weight. That is: N = mg mg + mv 2 2 R = 1+ v mg gR N mg g’s felt by rider = William Kim HSC Physics Summary | page 6  § Discuss the impact of the Earth’s orbital motion and its rotational motion on the launch of a rocketA moving platform offers a boost to the velocity of a projectile launched from it, if launched in the direction of motion of the platform. This principle is used in the launch of a rocket by considering that the Earth revolves around the Sun at 107,000km/h relative to the Sun and rotates once on its axis per day so that a point on the Equator has a rotational velocity of approximately 1,700km/h relative to the Sun. Hence, the Earth is itself a moving platform with two different motions which can be exploited in a rocket launch to gain a boost in velocity.Earth Orbit A rocket heading into orbit is launched to the east to receive a velocity boost from the Earth’s rotational motion. An Interplanetary Trip The flight of a rocket heading into space is timed so that it can head out in the direction of the Earth†™s motion and thereby receive an extra boost.  § Analyse the changing acceleration of a rocket during launch in terms of the: Law of Conservation of Momentum Forces experienced by astronauts Law of Conservation of Momentum Rocket engines generate thrust by burning fuel and expelling the resulting gases.Conservation of momentum means that as the gases move one way, the rocket moves the other. (Momentum before the burning is zero; hence the momentum after is also zero. The gases carry momentum in one direction down, and so the rocket carries an equal momentum in the opposite direction up. ) As fuel is consumed and the gases expelled, the mass of the system decreases. Since acceleration is proportional to the thrust and inversely proportional to the mass, as the mass decreases, the acceleration increases. Hence the forces on the astronauts increase.Forces Experienced by Astronauts g forces varied during the launch of Saturn V, a large three-stage rocket used to launch the Apollo sp acecraft. This is attributed to the sequential shutdown of the multiple rocket engines of each stage – a technique designed specifically to avoid extreme g forces. William Kim HSC Physics Summary | page 7  § Analyse the forces involved in uniform circular motion for a range of objects, including satellites orbiting the Earth Motion Whirling rock on a string Electron orbiting atomic nucleus Car cornering Moon revolving around Earth Satellite revolving around EarthFc Provided By†¦ The string Electron-nucleus electrical attraction Friction between tyres and road Moon-Earth gravitational attraction Satellite-Earth gravitational attraction  § Compare qualitatively and quantitatively low Earth and geostationary orbits Low Earth Orbit A low Earth orbit is generally an orbit higher than approximately 250 km, in order to avoid atmospheric drag, and lower than approximately 1000 km, which is the altitude at which the Van Allen radiation belts start to appear.The space shuttle utilises a low Earth orbit somewhere between 250 km and 400 km depending upon the mission. At 250 km, an orbiting spacecraft has a velocity of 27,900km/h and takes just 90 minutes to complete an orbit of the Earth. Geostationary Orbit A geostationary orbit is at an altitude at which the period of the orbit precisely matches that of the Earth. If over the Equator, such an orbit would allow a satellite to remain ‘parked’ over a fixed point on the surface of the Earth throughout the day and night.From the Earth such a satellite appears to be stationary in the sky, always located in the same direction regardless of the time of day. This is particularly useful for communications satellites because a receiving dish need only point to a fixed spot In the sky in order to remain in contact with the satellite. The altitude of such an orbit is approximately 38,800 km. If a satellite at this height is not positioned over the Equator but at some other latitude, it will not remain fi xed at one point in the sky.Instead, from the Earth the satellite will appear to trace out a ‘figure of eight’ path each 24 hours. It still has a period equal to the Earth’s, however, and so this orbit is referred to as geosynchronous. William Kim HSC Physics Summary | page 8  § Discuss the important of Newton’s Law of Universal Gravitation in understanding and calculating the motion of satellites Using Newton’s Law of Universal Gravitation combined with the expression for centripetal force, we can see that the orbital velocity required for a particular orbit depends nly on the mass of the Earth, the radius of the Earth and the altitude of the orbit (distance from the surface of the Earth). Given that the mass and radius of the Earth have fixed values, this means that altitude is the only variable that determines the specific velocity required. In addition, the greater the radius of the orbit, the lower the orbital velocity required. Once a launch ed rocket has achieved a sufficient altitude above the surface of the Earth, it can be accelerated into an orbit. It must attain a specific speed that is dependent only upon the mass and radius of the Earth and the altitude above it.If that speed is not reached, the spacecraft will spiral back in until it re-enters the atmosphere; if the speed is exceeded, it will spiral out. This can be considered by appreciating that the simplest orbital motion is a uniform speed along a circular path around the Earth. Uniform circular motion, as already mentioned, is a circular motion with a uniform orbital velocity. According to Newton’s First Law of Motion, a spacecraft in orbit around the Earth, or any object in circular motion, requires some force to keep it there, otherwise it would fly off at a tangent to the circle.This force is directed back towards the centre of the circle. In the case of spacecraft, it is the gravitational attraction between the Earth and the spacecraft that acts to maintain the circular motion that is the orbit. The force required to maintain circular motion, known as centripetal force, can be determined using the following equation: mv 2 FC = r The application of Newton’s Law of Universal Gravitation to the orbital motion of a satellite will produce an expression for the critical orbital velocity mentioned earlier.Recall that this law states that the gravitational attraction between a satellite and the Earth would be given by the following expression: m m FG = G E 2 S r This gravitational force of attraction also serves as the centripetal force for the circular orbital motion, hence: FG = FC Therefore, we can equate the formula for FG with that for FC: m E mS m S v 2 G = r r2 ? v = GmE r where v = orbital velocity (ms-1) where r = rE + altitude (m) William Kim HSC Physics Summary | page 9 Kepler’s Third Law: The Law of Periods Further, we can use the expression for orbital velocity to prove Kepler’s Third Law – the Law of Periods.The period or the time taken to complete one full orbit can be found by dividing the length of the orbit (the circumference of the circle) by the orbital velocity, v. 2? r T= v Changing the subject of this expression to v and then substituting into the formula for v given above: 2? r Gm E = T r 3 Gm E r ? 2 = T 4? 2 This means that for any satellite of the Earth at any altitude, the ratio r3:T2 always equals the same fixed value. William Kim HSC Physics Summary | page 10  § Describe how a slingshot effect is provided by planets for space probesMany of today’s space probes to distant planets such as Jupiter use a gravitational ‘slingshot’ effect (also known as a gravity-assist trajectory) that brings the probe close to other planets to increase the probe’s velocity. In 1974, Mariner 10 was directed past Venus on its way to Mercury. The Pioneer and Voyager probes also used this method. Consider a trip to Jupiter such as the Galileo prob e that involved a single fly-by of Venus and two of the Earth. As the probe approaches Venus, it is accelerated by Venus’ gravitational attraction, causing it to speed up relative to Venus. By Newton’s Third Law, Venus will also experience a force slowing it down. It’s mass, however, is so much greater than that of the probe that the velocity decrease is imperceptible. ) As the probe passes Venus, its speed is reduced (relative to Venus). Relative to the Sun, however, its speed has increased. The probe picks up angular momentum from the planet (which loses an equal amount of an angular momentum). Gravity allows the ‘coupling’ between the probe and planet to facilitate the transfer. For this reason, gravity-assist trajectories should more correctly be called angular momentum-assist trajectories. f = vi + 2Vi Planet vi Spacecraft Vi Vf  § Account for the orbital decay of satellites in low Earth orbit All satellites in low Earth orbit are subject to some degree of atmospheric drag that will eventually decay their orbit and limit their lifetimes. As a satellite slows, it loses altitude and begins a slow spiral downwards. As it descends, it encounters higher density air and higher drag, speeding up the process. By the time the satellite is below an altitude of 200 km it has only a few hours left before colliding with the Earth. The re-entry process generates much heat and most satellites burn up (vaporise) before impacting.William Kim HSC Physics Summary | page 11  § Discuss issues associated with safe re-entry into the Earth’s atmosphere and landing on the Earth’s surface There are significant technical difficulties involved in safe re-entry, the most important being: 1. The heat generated as the spacecraft contacts the Earth’s atmosphere; and 2. Keeping the retarding-forces (g-forces) within safe limits for humans. Heating Effects The Earth’s atmosphere provides aerodynamic drag on the spacecraft a nd as a result high temperatures are generated by friction with air molecules. Identify that there is an optimum angle for re-entry into the Earth’s atmosphere and the consequences of failing to achieve this angle. g-Forces The angle of re-entry is critical: too shallow and the spacecraft will bounce off the atmosphere back into space; too steep and the g-forces will be too great for the crew to survive (and the temperatures generated with the atmosphere will be too high even for the refracting materials used). The ‘allowed’ angle of re-entry is –6. 2 °  ± 1 ° relative to the Earth’s horizon. William Kim HSC Physics Summary | page 12 3.Future space travel and exploration will entail a combination of new technologies based on current and emerging knowledge  § Discuss the limitation of current maximum velocities being too slow for extended space travel to be viable Scientists have not yet been able to produce speeds of spacecraft more than a f ew tens of thousands of kilometres per hour. When travelling to distant planetary objects, the engines of spacecraft are not on as spacecraft rely on inertia to move along. To increase the speed significantly would require the engines to be operating, which would require more fuel.More fuel would require more thrust putting the spacecraft into orbit, which would require more fuel and so on. To increase the speed of spacecraft to values that would make interplanetary travel feasible requires a whole new technology (one not based on the emission of gases produced by combustion). Clearly, while current maximum velocities are just adequate for interplanetary travel, they are entirely inadequate for interstellar travel.  § Describe difficulties associated with effective and reliable communications between satellites and earth caused by: – distance – van Allen radiation belts – sunspot activityDistance Microwaves and radio waves, like all EM waves, travel through sp ace at the speed of light. This is the fastest speed possible in our universe and therefore places a limit on the speed and response time of space communications. The immense distance involved in space communications creates a distance-related time lag. Also, as EM radiation obeys an inverse square law, there is a loss of signal strength as distance increases. This is referred to as space loss. Van Allen radiation belts There are two belts of energetic charged particles, mainly electrons and protons, lying at right angles to the equator of the Earth.Some of the solar wind particles become trapped in the Van Allen radiation belts. Intense solar activity can disrupt the Van Allen Belts. This in turn is associated with auroras and magnetic storms. The charged particles drifting around the Earth in the outer belt corresponds to an electric current and hence has an associated magnetic field. Once or twice a month this current increases and as a result its magnetic field increases. This c an lead to interference of short wave radio communication, errors in communication satellites and even failure of electrical transmission lines.Sunspot activity Sunspots are associated with the solar wind (consisting of a stream of charged particles). The solar wind affects the Earth’s magnetic field and this in turn affects radio communication. William Kim HSC Physics Summary | page 13 4. Current and emerging understanding about time and space has been dependent upon earlier models of the transmission of light  § Outline the features of the ether model for the transmission of light It was believed that light waves require a medium to propagate. Although nobody could find such a medium, belief in its existence was so strong that it was given a name – the ether.The ether: – Filled all of space, had low density and was perfectly transparent – Permeated all matter and yet was completely permeable to material objects – Had great elasticity to support and propagate the light waves  § Describe and evaluate the Michelson-Morley attempt to measure the relative velocity of the Earth through the ether The Ether Wind Because the Earth was moving around the Sun, it was reasoned that an ether wind should be blowing past the Earth. However, if a wind blows, the speed of sound relative to the stationary observer would vary.Thus it was believed that the speed of light should vary due to the presence of the â€Å"ether wind†. It was in an attempt to detect this difference that Michelson and Morley did their famous experiment. The Michelson-Morley Experiment Light sent from S is split into two perpendicular beams by the half-silvered mirror at A. These two beams are then reflected back by the mirrors M1 and M2 and are recombined in the observer’s eye. An interference pattern results from these two beams. The beam AM1 travelled across the ether, whilst AM2 travelled with and against the ether.The times to do this can be shown to be different and so introduce a phase difference between the beams. When the entire apparatus was rotated through 90 °, a change in the interference pattern was expected. None was observed. The result of the Michelson-Morley experiment was that no motion of the Earth relative to the ether was detectable. M1 A S M2 Ether Wind  § Discuss the role of critical experiments in science, such as Michelson-Morley’s, in making determinations about competing theories From a hypothesis, predictions are made of what should happen if a particular experiment is performed.If the results are not in agreement with the prediction, the hypothesis is incorrect. As we have seen, the fact that a null result was found from this experiment showed the ether hypothesis to be invalid. This opened up a completely revolutionary view of space and time with the work of Einstein. William Kim HSC Physics Summary | page 14  § Outline the nature of inertial frames of reference Frames of Reference Frame s of reference are objects or coordinate systems with respect to which we take measurements. Position In maths, the Cartesian coordinate system is used and position is referred to the axes x, y and z.In experiments in class, the laboratory is the frame of reference. S S' r u r P v Velocity An object P travels with velocity v with respect to a reference frame S. Another frame S’ moves with velocity u relative to S. The velocity of P relative to S’ is v’ = v – u. Velocity thus depends upon the reference frame. Inertial Frames of Reference An inertial frame of reference is one that is moving with constant velocity or is at rest (the two conditions being indistinguishable). In such reference frames, Newton’s Law of Inertia holds. A non-inertial frame of reference is one that is accelerating.  § Discuss the principle of relativityThree hundred years before Einstein, Galileo posed a simple idea, now called the principle of relativity, which states that all steady motion is relative and cannot be detected without reference to an outside point. This idea can be found built into Newton’s First Law of Motion as well. Two points to be reinforced:  § The principle of relativity applies only for non-accelerated steady motion  § This principle states that within an inertial frame of reference you cannot perform any mechanical experiment or observation that would reveal to you whether you were moving with uniform velocity or standing still.William Kim HSC Physics Summary | page 15  § Identify the significance of Einstein’s assumption of the constancy of the speed of light In 1905, Albert Einstein proposed that the speed of light is constant and is independent of the speed of the source or the observer. This premise explained the ‘negative’ result of the MichelsonMorley experiment and showed that the ether concept was not needed. As a consequence of this ‘law of light’ it can be shown that ther e is no such thing as an absolute frame of reference. All inertial reference frames are equivalent. That is, all motion is relative.The laws of physics are the same in all frames of reference; that is, the principle of relativity always holds.  § Recognise that if c is constant then space and time become relative In Newtonian physics, distance and velocity can be relative terms, but time is an absolute and fundamental quantity. Einstein radically altered the assumptions of Newtonian physics so that now the speed of light is absolute, and space and time are both relative quantities that depend upon the motion of the observer. (Our reality is what we measure it to be. Reality and observation cannot be separated. Remember this as we proceed).  §Discuss the concept that length standards are defined in terms of time with reference to the original meter †¦In other words, the measured length of an object and the time taken by an event depend entirely upon the velocity of the obser ver. (This is why our current standard of length is defined in terms of time – the metre is the distance travelled by light in a vacuum in the fraction 1/299792458 of a second).  § Identify the usefulness of discussing space/time, rather than simple space †¦Further to this, since neither space nor time is absolute, the theory of relativity has replaced them with the concept of a space-time continuum. Space and time, not just space, are relative quantities).  § Account for the need, when considering space/time, to define events using four dimensions †¦Any event then has four dimensions (three space coordinates plus a time coordinate) that fully define its position within its frame of reference. William Kim HSC Physics Summary | page 16  § Explain qualitatively and quantitatively the consequence of special relativity in relation to: The relativity of simultaneity The equivalence between mass and energy Length contraction Time dilationThe Relativity of Simultanei ty (simultaneity and the velocity of light) Observers in relative motion will disagree on the simultaneity of events separated in space. The Equivalence Between Mass and Energy The mass of a ‘moving’ object is greater than when it is ‘stationary’ – it experiences mass dilation (covered later). Since c is the maximum speed in the universe it follows that a steady force applied to an object cannot continue to accelerate. It follows that the inertia, that is the resistance to acceleration, must increase.But inertia is a measure of mass and so the mass has increased. It is this increase in mass that prevents any object from exceeding the speed of light, because as it accelerates to higher velocities its mass increases, which means that further accelerations will require even greater force. This is further complicated by time dilation because, as speeds increase to near light speed, any applied force has less and less time in which to act. The combined ef fect is that as mass becomes infinite and time dilates, an infinite force would be required to achieve any acceleration at all.Sufficient force can never be supplied to accelerate beyond the speed of light. If force is applied to an object, then work is done on it – energy is given to the object. This energy would take the form of increased kinetic energy as the object speeds up. But at near light speed the object does not speed up. The applied force is giving energy to the object and the object does not acquire the kinetic energy we would expect. Instead, it acquires extra mass. Einstein made an inference here and stated that the mass (or inertia) of the object contained the extra energy.Relativity results in a new definition of energy as follows: E = E k + mc 2 where E = total energy, Ek = kinetic energy, m = mass, c = speed of light When an object is stationary, it has no kinetic energy, but still has some energy due to its mass. This is called its mass energy or rest ener gy and is given by: 8 -1 E = mc 2 where E = rest energy (J), m = mass (kg), c = speed of light (3 x 10 m s ) William Kim HSC Physics Summary | page 17 Implications of Special Relativity: To measure speed we need to measure distance and time. If c remains constant, then it follows that distance (length) and time must change.Space and time are relative concepts. Length Contraction (the Lorentz-FitzGerald Contraction) The length of a ‘moving’ rod appears to contract in the direction of motion relative to a ‘stationary’ observer. l = l0 1 ? v2 c2 where l is the moving length, l0 is the ‘rest’ length (that is, the length as measured by an observer at rest with respect to the rod) and v is the speed of the rod. Time Dilation Time in a ‘moving’ frame appears to go slower relative to a ‘stationary’ observer t= t0 1? v c2 2 where t is the observed time for a ‘stationary’ observer and t0 is the time for an observer travelling in the frame. 0 is called the proper time (this is the time measured by an observer present at the same location as the events that indicate the start and end of an event). Mass Dilation The mass of a ‘moving’ object is greater than when it is ‘stationary’. m= m0 1? v2 c2 where m is the mass for a ‘moving’ object and m0 is the mass for that object when it is ‘stationary. ’  § Discuss the implications of time dilation and length contraction for space travel The relativity of time allows for space travel into the future but not into the past.When travelling at relativistic speeds (0. 1c or faster), relativity influences the time that passes on the spacecraft. Astronauts on a relativistic interstellar journey would find their trip has taken fewer years than observed on Earth. William Kim HSC Physics Summary | page 18 Core Topic Two: Motors and Generators 1. Motors use the effect of forces on current-carrying conductors in magnetic fields  § Identify that moving charged particles in a magnetic field experience a force Charged particles moving in an external magnetic field will experience a force.If the moving charged particles are flowing through, and confined within, a conductor that is in an external magnetic field, the conductor will also experience a force. This effect is known as the motor effect. F = qvB Use left hand â€Å"FBI gun† An example: Van Allen Radiation Belts The Earth’s magnetic field captures charged particles from the solar wind (low energy) and cosmic rays (high energy). The charges are force to spiral along the field lines accumulating into two doughnut-shaped belts of â€Å"radiation† called the upper and lower Van Allen radiation belts.William Kim HSC Physics Summary | page 19  § Discuss the effect, on the magnitude of the force on a current-carrying conductor, of variations in: The strength of the magnetic field in which it is located The magnitude of the current in the conductor The length of the conductor in the external magnetic field The angle between the direction of the external magnetic field and the direction of the length of the conductor †¦The force is proportional to the magnetic field strength, B †¦The force is proportional to the current, I †¦The force is proportional to the length, L The force is at a maximum when the conductor is at right angles to the field, and is zero when the conductor is parallel to the field. The magnitude of the force is proportional to the component of the field that is at right angles to the conductor. F = BIl sin ? William Kim HSC Physics Summary | page 20  § Describe qualitatively and quantitatively the force on long parallel current-carrying conductors: Ampere’s Law Two parallel wires, each carrying a current, will exert a force on the other. This happens because each current produces a magnetic field (as in Oersted’s experiment).Therefore each wire finds itself carrying a current across the magnetic field produced by the other wire and hence experiences a force. Determining the magnitude of the force between two parallel conductors The magnetic field strength at a distance, d, from a long straight conductor carrying a current, I, can be found using the formula: kI B= d -7 -2 where k = 2. 0 x 10 N A The magnitude of the force experienced by a length, l, of a conductor due to to an external magnetic field is: F = I 2 lB or ? kI ? F = I 2l ? 1 ? ? d ? rearranged F II =k 1 2 l d F II =k 1 2 l d (Ampere’s law) I1 I2 If currents are in the same direction, then the conductors will attract. If currents are in opposite directions, then the conductors will repel. William Kim HSC Physics Summary | page 21  § Define torque as the turning moment of a force using: Torque is turning force. Its’ units are Newton-metres (Nm). ? = Fd where ? = torque, in Nm F = force, in N D = distance from rotational axis, in m F = BIl ? =BIld Rotat ional axis d ? = Fd  § Identify the forces experienced by a currentcarrying loop in a magnetic field and describe the net result of the forces b max ? = nBIA zero ? b Current Loops N I F = BIl ? =BIld ? = ? 1 + ? 2 = BIld + BIld = 2 BIld = BI (l ? 2d ) = BIA S ? = nBIA cos ? ? b (For each turn of the loop) Generally, ? =nBIA cos ? William Kim HSC Physics Summary | page 22  § Account for the motor effect due to the force acting on a current-carrying conductor in a magnetic field The motor effect Recall that charged particles moving in an external magnetic field will experience a force. If the moving charged particles are flowing through, and confined within, a conductor that is in an external magnetic field, the conductor will also experience a force.An electric motor is a device that transforms electrical potential energy into rotational kinetic energy.  § Describe the main features of a DC electric motor  § Discuss the importance of the invention of the commutator for devel oping electric motors  § Describe the role of the metal split ring and the brushes in the operation of the commutator Anatomy of a DC motor – Permanent magnets: provide an external magnetic field in which the coil rotates. As the magnets are fixed, they are known as the stator. – Rotating coil: carries a direct current that interacts with the magnetic field, producing torque. Armature: is made of ferromagnetic material and allows the coil to rotate freely on an axle. The armature and coil together are known as the rotor. The armature protrudes from the motor casing, enabling the movement of the coil to be used to do work. – Commutators: reverse the current of the coil every half turn to maintain consistent direction and torque. It is a mechanical switch that automatically changes the direction of the current flowing through the coil when the torque falls to zero. – Brushes: maintain electrical contact of coils with the rest of the circuit.The developmen t of DC motors outstripped that of AC motors and generators for two reasons: – Voltaic batteries could supply power – They could use powerful electromagnets that were far stronger than permanent magnets The development of the commutator was important because it led to the development of modern electric motors and generators. It enabled motors to provide steady circular motion of a drive shaft.  § Describe how the required magnetic fields can be produced either by currentcarrying coils or permanent magnets The magnetic field of a DC motor can be provided either by permanent magnets or by electromagnets.William Kim HSC Physics Summary | page 23 2. The relative motion between a conductor and magnetic field is used to generate an electrical voltage  § Outline Michael Faraday’s discovery of the generation of an electric current by a moving magnet Faraday had found that 3 things are necessary to generate (or â€Å"induce†) an EMF (voltage supply): – A magnetic field (from some magnets or electromagnet) – A conductor (eg. wire or coil of wire) – Relative motion / change between the field and the conductor If the conductor formed a closed loop then an induced current would also flow. ire If this wire is dropped so that it cuts flux lines, then a voltage appears between the ends because electrons are forced to the right. They eventually stop moving because they create an electric field pushing them back. As long as the magnet is moving, an emf and current is induced. Faraday’s Law ? =? n ? where ? = induced EMF, in V n = number of turns on coil ? = change in ? = magnetic flux, in Wb = BA B = magnetic flux density (field strength), in T The induced voltage can be increased by: Increasing n: more turns on the coil Increasing B: use strong magnets Increasing A: use a bigger coil Decreasing t: go faster! B A = area of coil in m 2 ? = time taken for to occur William Kim HSC Physics Summary | page 24  § Define ma gnetic field strength B as magnetic flux density Magnetic flux density is the magnetic flux per unit area and is a measure of the magnetic field strength.  § Explain the concept of magnetic flux in terms of magnetic flux density and surface area ? = BA sin ? where B = magnetic flux density, in T A = area, in m 2 ? = magnetic flux, in Wb  § Explain generated potential difference as the rate of change of magnetic flux through a circuit The induced emf is proportional to the rate of change of flux through the circuit.See Faraday’s Law (above).  § Account for Lenz’s Law in terms of conservation of energy and relate it to the production of back emf in motors Lenz’s Law This is a supplementary law to Faraday’s Law. It says that any induced emf or current will have a direction that opposes the change that caused it. This is really just a restatement of the law of conservation of energy because the induced electrical energy has come from the thing that caus es the original motion. Eg. In a hydroelectric power station, the kinetic energy of flowing water is converted into electrical energy. NWilliam Kim HSC Physics Summary | page 25  § Explain that, in electric motors, back emf opposes the supply emf Back emf Back emf is generated in any coil that experiences changing B fields, even though it is producing them. Note that back emf is frequency dependent – the higher the frequency of the changing field, the greater the back emf produced. Back emf is also produced in the rotating coil of a motor: – When the motor is spinning at its operating speed, back emf will have its max value, but†¦ – When the motor is just turned on it isn’t spinning yet so there is no back emf. This can lead to excessive current so the motor may be protected by using a â€Å"starting resistance† that limits current. When up to speed the resistor is taken out of the circuit. The coil becomes an electromagnet and generates an alternating B field BUT it also experiences the changing B field and generates its own emf that opposes the applied emf.  § Apply Lenz’s Law to the production of eddy currents Eddy Currents – are induced currents (usually unwanted or unintended) in two-dimensional conductors (eg. sheet metal) or three-dimensional conductors (eg. a block of steel).Sometimes it is necessary to design against them. Eg. the core of a motor is made of soft iron, and is made of thin layers (laminated) to prevent eddy currents. Some devices rely on eddy currents to work: Electromagnetic braking – a moving conductor near magnets will slow down because the eddy currents oppose its motion. Electromagnetic switching – security ‘gates’ that are really coils with AC generate a high frequency B field. Metal in this field develops eddy currents that work against the field, slowing it down. A detector circuit picks up on this and sets off an alarm.Induction Cooktops- are a n application of Faraday’s Law. Instead of a heating element, this cooktop contains a set of coils with alternating current passing through them. This produces a changing B field above the cooktop. A metal saucepan placed on the cooktop is a conductor in the changing B field and therefore an electric current is induced in the base of the pan. The current heats the pan, and this heat cooks the food. Induction cooktops are approximately twice as efficient as a gas cooktop, but are expensive to purchase. William Kim HSC Physics Summary | page 26 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Movement of metal Eddy current loop 3. Generators are used to provide large scale power production in isolated areas and as a backup in emergency situations  § Identify the main components of a generator An electric generator (dynamo) is a device that includes all of the elements necessary to transform mechanical kinetic energy to electricity according to Faraday’s Law: – A magnetic field (provided by a set of permanent magnets); – A conductor (a coil mounted on an axle, so it can spin); – Relative motion (the coil is made to spin by some other form of energy). Compare the structure and function of a generator to an electric motor In fact, most generators are constructed just like a motor, however the flow of energy through them is different. Motor: electrical energy a kinetic energy Generator: kinetic energy a electrical energy  § Describe the operation of an AC and a DC generator EMF is generated in the coil and a circuit is completed to the outside world through ring connectors, just like motors. If standard slip rings are used then a dynamo naturally produces alternating current AC. I t E t Doubling the frequency of rotation doubles the maximum induced emf If a split ring commutator is used instead, then the direction of the current flowing from the coil is reversed every ? cycle. This produces a pu lsing type of direct current DC. + I t William Kim HSC Physics Summary | page 27  § Discuss the energy losses that occur as energy is fed through transmission lines from the generator to the consumer Analyse the effects of the development of AC and DC generators on society and the environmentEven good electrical conductors like copper used to supply electricity, sometimes through considerable cable lengths to towns and cities, generate substantial resistances. It follows that to minimise energy loss in the wires, the current needs to be kept low (heating losses vary as the square of the current). This is achieved by transmitting the energy at high voltages.  § Impact on society – Impact on environment – Positive Improved lifestyle Street lighting Electric trains Communication Computerisation of many systems eg. anking, stock market Industrial development a more jobs Lots of electric trains have reduced pollution from steam trains and made public transport more avai lable Electricity has replaced older, more-polluting technologies eg. electrical heating instead of coal burning in fireplaces – Negative Possible risk of cancer living near distribution cables Longer working hours Reliance on electricity leaves us vulnerable to systems loss due to electrical failure – – –Burning coal in power stations produces smoke and CO2 (a greenhouse gas) Nuclear power stations produce radioactive water & have a risk of nuclear accident Hydroelectric schemes redirect water away from river habitats Mining impacts negatively on environment Visual pollution of cables  § Assess evidence about the physiological effects on humans living near high voltage power lines 1979 study found children living near high voltage power lines appeared to develop a particular form of cancer. 997 study showed no evidence of an increase risk of childhood cancer at residential magnetic field levels. 1998 panel stated that EM fields should be considered â⠂¬Å"possible human carcinogens† and that there is â€Å"no conclusive and consistent evidence that EM fields cause any human disease. † William Kim HSC Physics Summary | page 28 4. Transformers allow generated voltage to be either increased or decreased before it is used  § Explain the purpose and principles of transformers in electrical circuits A transformer is a device that alters the voltage and current of an electricity supply.The AC voltage source produces an alternating current in the primary coil. This produces an alternating B field that threads through the secondary coil. The secondary coil now has: – Conductor – B field – Change and therefore generates its own voltage. If there is a closed loop then an alternating current will flow as well.  § Compare step-up and stepdown transformers Step-up transformers: increase voltage and decrease current Step-down transformers: decrease voltage and increase current  §Determine the relationship between the ratio of the number of turns in the primary and secondary coils and the ratio of primary to secondary voltage Vp = primary voltage (voltage in) Ip = primary current np = number of turns on primary coil Vs = secondary voltage (voltage out) Is = secondary current ns = number of turns on secondary coil Vp Vs = np ns If 100% efficient (this needs perfect â€Å"flux linkage†, usually using an iron core) then: Power in primary = Power in secondary ? V p I p = Vs I s ? ? Vp Vs Vp Vs = = Is Ip np ns = Is IpWilliam Kim HSC Physics Summary | page 29  § Explain why voltage transformations are related to the conservation of energy The Principle of Conservation of Energy states that energy cannot be created or destroyed but that it can be transformed from one form to another. This means that if a step-up transformer gives a greater voltage at the output, its current must be decreased: i. e. power in = power out.  § Explain the role of transformers in electricity sub-stati ons NSW power stations produce electricity with a voltage of about 23,000 V and a current of about 30,000 A.Unfortunately, this amount is too high to be sent through a cable. This is because it heats the cable causing energy loss. This is called joule heating and happens because: P = I2R So to reduce joule heating, the current must be reduced as much as possible with a step-up transformer. Additional transformers between the power station and consumer (in sub-stations) gradually stepdown the voltage, to 240 V by the time it gets to household users. This is because at high voltages, electricity can conduct through air, making it dangerous for use in the home. Discuss why some electrical appliances in the home that are connected to the mains domestic power supply use a transformer Most electronic circuits are designed to operate at low DC voltages of between 3 V and 12 V. Therefore, household appliances that have electronic circuits in them will have either a plug-in transformer or an inbuilt transformer to step down the domestic 240 V supply. These transformers also have a rectifier circuit built into them that converts AC to DC.TVs also contain a step-up transformer for producing the high voltages needed for the CRT.  § Analyse the impact of the development of transformers on society The development of the generator and transformer has allowed for the setting up of national power grids in almost every country, making that most convenient and flexible form of energy, electricity, accessible from many miles away. The transformer’s role is to step voltage up and down to make efficient transportation and distribution possible. William Kim HSC Physics Summary | page 30 5.Motors are used in industries and the home usually to convert electrical energy into more useful forms of energy  § Describe the main features of an AC electric motor AC induction motor: – The rotor – end rings short circuit non-ferrous rotor bars, that is sealed i. e. no e xternal connections at all (usually a â€Å"squirrel cage†). Encased in a laminated iron armature. – The stator – surrounding electromagnet. – Connection to stator – the surrounding electromagnet receives the AC. In an AC induction motor, the principle of operation is: 1. AC to surrounding electromagnet, which†¦ 2.Produces an oscillating (rotating) B field, which†¦ 3. Induces a current in the rotor, which†¦ 4. Turns the rotor into an electromagnet that†¦ 5. Tries to oppose the field being generated by the stator. 6. The stator and the rotor push against each other (using their B fields), which†¦ 7. Causes the rotor to turn! Brilliant! AC (synchronous) motor: – A rotating coil – Surrounding magnets – Connection to coil via slip rings (commutator for DC motor)  § Explain that AC motors usually produce low power and relate this to their use in power tools Power is the rate of work. Work is done when ener gy is transformed from one type to another.Induction motors are considered to produce low power because the amount of mechanical work they achieve is low compared with the electrical energy consumed. The ‘lost power’ of induction motors is consumed in magnetising the working parts of the motor and in creating induction currents in the rotor. AC induction motors are considered to be unsuitable for use in heavy industry because their low power rating would make them too expensive to run when performing a specific task. However, they are used extensively in power tools and electric domestic appliances where the loss of power is not economically significant. Explain the advantages of induction motors Advantages of AC induction motors: 1. Simplicity of design; 2. High efficiency (hence low maintenance – there are no brushes or commutators to wear out); 3. Relatively low cost William Kim HSC Physics Summary | page 31 Core Topic Three: From Ideas to Implementation 1. In creased understandings of cathode rays led to the development of television  § Explain that cathode ray tubes allowed the manipulation of a stream of charged particles Discharge Tubes – Investigation of vacuum tubes could not occur until good vacuum pumps had been invented.A vacuum tube is a glass tube fitted with an electrode at either end, and almost all of the air sucked out. – The positive electrode is the â€Å"anode†; The negative electrode is the â€Å"cathode†. When a high voltage is connected between the electrodes, an invisible ray travels from the cathode to the anode. They were called â€Å"cathode rays†. Cathode rays cause glass to glow green. – A discharge tube is a cathode ray tube with a vacuum pump fitted, so that the air pressure inside the tube can be varied. At different air pressures, different bright effects appear in the tubes e. . bands, striations and dark spaces. These are caused by cathode rays striking atoms in the air inside the tube. The atoms become excited then release photons of visible light – A beam of electrons travels from the cathode to the anode and can be deflected by electrical and/or magnetic fields. Anode Glass glows here Cathode  § Explain why the apparent inconsistent behaviour of cathode rays caused debate as to whether they were charged particles or electromagnetic waves In 1892 Hertz demonstrated that cathode rays could penetrate thin metal foils.This he believed supported a wave nature. In 1895 Jean-Baptise Perrin showed that cathode rays deposited negative charges on impact with an object, suggesting a particle nature. There was controversy over the nature of cathode rays – waves or particles. William Kim HSC Physics Summary | page 32  § Identify that charged plates produce an electric field If metal plates are separated by a distance and are attached to a power source, an electric field will be produced between them. E = V/d  § Describe quantitati vely the force acting on a charge moving through a magnetic fieldRecall that the force (F) acting on a charge (q) moving with a velocity (v) at an angle to a magnetic field (B), is given by: FB = qvB Where FB = magnetic force (N) q = charge (C) v = velocity of charge (ms-1) B = magnetic field strength (T)  § Discuss qualitatively the electric field strength due to a point charge, positive and negative charges and oppositely charged parallel plates. Describe quantitatively the electric field due to oppositely charged parallel plates ++++++++ If a positive charge is placed near another positive charge, it will experience a force of repulsion.A positive charge placed in a field will experience a force in the direction of the arrow. A negative charge placed in a field will experience a force opposite to the direction of the arrow.  § FE = qE Where FE = electric force (N) q = charge (C) E = electric field strength (NC-1) ———– William Kim HSC Physics Summar y | page 33  § Outline Thomson’s experiment to measure the charge/mass ratio of an electron Cathode ray particles ? v? B ? ? ? ? ? ? ? FM ? ? FE ? ? ? v? E ? ? ? J. J. Thomson’s Experiment – By fitting plates to his CRT, he could subject the cathode rays to an electric field.The rays deflected, proving that they were charged particles, not electromagnetic waves. – He noticed that the rays deflected toward the positive plate, proving that they were negatively charged particles. – By crossing electric and magnetic fields, Thomson was able to deduce the velocity of the cathode rays. By turning off the E field, the particles followed a circular arc caused by the B field. The magnetic force was acting like a centripetal force. mv qvB = r q v ? = m Br – 2 ? FM = FE qvB = qE E ? v = B Thomson adjusted the strength of the fields so that the particles were not deflected.By carefully measuring the strength of the fields, Thomson could calculate v. T homson had already measured B and worked out v. By measuring the radius of curvature r, he could then calculate q/m, i. e. the charge/mass ratio of an electron. q/m for these particles was 1800 times greater than for a hydrogen ion, the simplest known atomic ion. Thomson quickly compared the charges and found them to be about the same (though opposite in sign) Therefore mass for cathode ray particles was 1800 times smaller than hydrogen Therefore cathode ray particles were subatomic particles!This was the first discovery of subatomic particles They were later called electrons. William Kim HSC Physics Summary | page 34  § Outline the role in a cathode ray tube of: Electrodes in the electrode gun The electric field The fluorescent screen The Cathode Ray Tube Each CRT has a vacuum tube/chamber, a cathode, an anode, and a target. Electrodes in the electron gun The electron gun produces a narrow beam of electrons. It consists of a filament, a cathode and two open-cylinder anodes. The a nodes help to accelerate and focus the electrons.A ring shaped electrode – the grid – between the cathode and anodes controls the brightness of the spot by controlling the number of electrons emitted by the gun. By making the grid negative with respect to the cathode the number of electrons, and hence the brightness is reduced. The electric field Acts as a deflection system. It consists of two sets of parallel plates connected to a parallel plates connected to a potential difference. This produces an electric field between the plates. The Y-plates control the vertical deflection and the X-plates the horizontal deflection.The fluorescent screen The inside glass of the end of the tube is coated with a fluorescent material for example, zinc sulphide. When an electron beam hits the screen, the coating fluoresces and a spot of light is seen on the screen. The screen acts as a detector of cathode rays. Electrons Cathode Anode To plates and screen William Kim HSC Physics Summ ary | page 35  § Outline applications of cathode rays in oscilloscopes, electron microscopes and television sets The Cathode Ray Oscilloscope (CRO) Is an electronics diagnostics device because it can show a graph of how voltages vary over time.Deflection of the electron beam is achieved by two sets of plates. Horizontal plates cause vertical deflection while vertical plates cause horizontal deflection. TV Tube An electron gun again produces the electron beam. Coils are used instead of plates, however. Electric current through the coils produce magnetic fields that can deflect the beams quickly from side to side, and more slowly from bottom to top. In this way the beam scans the entire screen. By varying the intensity of the beam, a picture is built up. The picture is refreshed 50 times / second, which is too fast to be noticed by the human eye.The Electron Microscope Uses electrons instead of light. Their wavelength is 100,000 times smaller than visible light, therefore their reso lving power is 100,000 times greater. – A â€Å"sample† is placed inside the chamber (which is really the CRT) – The air is then sucked out – An electron gun produces the electron beam – Coils produce magnetic fields to focus the beam (â€Å"magnetic lenses†) – The beam scans over the surface of the sample – Detectors pick up the reflected and scattered electron beam, and from this information a 3 dimensional image is constructed  §Discuss the impact of increased understandings of cathode rays and the development of the oscilloscope on experimental physics The introduction of electronic control systems into all forms of science and industry has seen the cathode ray oscilloscope (CRO) become one of the most widely utilised test instruments. Because of its ability to make ‘voltages’ visible, the cathode ray oscilloscope is a powerful diagnostic and development tool. William Kim HSC Physics Summary | page 36 2.The r econceptualisation of the model of light led to an understanding of the photoelectric effect and black body radiation  § Explain qualitatively Hertz’s experiments in measuring the speed of radio waves and how they relate to light waves Recall: Maxwell’s theory of electromagnetic waves In 1864 Maxwell, through a set of four brilliant equations, predicted a range of invisible waves made up of an electric and magnetic wave that regenerate each other. The speed of these waves was calculated to be 3 x 108 ms-1 and probably included light.E v B Heinrich Hertz’s Experiment: (proving Maxwell’s theory) Performed in 1886, Hertz built equipment to generate and transmit EM waves with ? ? 1m. He also had a separate receiver (a loop of wire) located about 20m away. Spark gaps were included to show when high voltage AC was present in the transmitter or receiver. The receiver spark only appeared when the transmitter spark was present. Hertz hypothesised that the sparks set up changing electric and magnetic fields that propagated as an electromagnetic ave, as postulated by Maxwell. He showed that these were waves being transmitted because he could reflect, refract and polarise them. By measuring the frequency, he calculated v (v = f ? ) and it came out as 3 x 108 ms-1. These properties proved Maxwell’s theory and as they are also exhibited by light, Hertz was able to provide experimental evidence that light is a form of transverse electromagnetic wave. to induction coil < 1mm gap transmitter charged plates receiver William Kim HSC Physics Summary | page 37  §Describe Hertz’s observation of the effect of a radio wave on a receiver and the photoelectric effect he produced but failed to investigate Outline applications of the production of electromagnetic waves by oscillating electric charges in radio antennae Hertz observed that the transmitter spark was producing s

Natural Disasters in the Caribbean

The natural disasters that are typically experienced in the Caribbean can have catastrophic and devastating impacts on the environment, economic development and social structure of these islands. Severe damage to the built infrastructure that has supported communities on Caribbean islands for decades can place a huge strain on economic activity. The social impacts that are experienced following natural disasters consist of homelessness, injury, suffering, sickness, disease, and even death.This paper will introduce the major natural disasters that have affected life in the Caribbean and they include hurricanes, earthquakes, volcanoes, landslides, flooding and tsunamis. Other than Barbados, all Windward Islands of the Caribbean are of volcanic origin. Volcanoes are ruptures in the earth’s surface that allow for the escape of lava and gas. The two types of volcanic eruptions, explosive and effusive, can both have devastating consequences on the environment and the Caribbean inhab itants.Although not a common occurrence, several volcanic eruptions have take place on Caribbean islands. For example, an eruption on St. Vincent in 1979 left economic losses of 1 billion dollars, but fortunately no casualties. Flooding is another very impactful natural disaster that is one of the more common types of natural disasters to greatly affect CARICOM countries. Sometimes called the silent killer, flooding can greatly affect socio-economic development.Whether it is coastal or river flooding, it has the ability to greatly damage the agricultural landscape as well as introduce water-borne disease that can lead to death in local inhabitants. There is a disproportionate vulnerability of CARICOM countries to natural disaster demonstrated by the numerous events that have occurred over the last few hundred years. The intrinsic vulnerability is due to the small size of Caribbean islands, their insularity and remoteness, and the economic, environmental and demographic factors that are associated with these islands.Furthermore, there is limited hazard forecasting ability for several CARICOM countries. The CARICOM countries are geographically set in a location that makes them vulnerable to natural disasters. The Caribbean climate is tropical and temperatures range between approximately 24 °C and 32 °C throughout all islands as a whole. The prevailing trade winds along with year round sunny skies set a warm climate for CARICOM countries with both dry and wet season.Precipitation depends on the elevation of the island and is also effected by water currents. The environmental impacts of Caribbean natural disasters are correlated with the large coastal zones on the numerous islands and the damage can vary from affecting the entire landscape or the falling on one tree. It was noted that from 1960-1989, â€Å"hurricanes in the Greater Caribbean Basin resulted in the deaths of 28,000 people, disrupted the lives of 6 million people and destroyed property worth U. S. $16 billion. All the Caribbean nations that have already faced the fury of the hurricane Sandy and have had to fight back by burying the dead, finding shelter for the homeless and counting the economic losses. Sandy moved northwards with gusts in over 110 mph destroying homes, crops and roads on its way. More than 69 people were killed in six countries. Even though Haiti was not in Sandy’s direct path, the island was greatly affected as Haiti has confirmed that 52 people have dead and a lot of people are missing. Buildings were engulfed in mudslides or swept out to sea by flood tides.The Government in Port-au-Prince declared that about 200,000 people are homeless and only 17,000 shelters have been provided. The country has short-term fears of cholera and other water-borne disease and besides that there is also a huge food shortages because the agricultural landscape has been badly damaged by the hurricane Sandy. Smaller scale fatalities and damage were also reported in Jam aica, the Dominican Republic, Puerto Rico and the Bahamas, where seawaters surged over coastal barriers to deluge roads and buildings.February 8th, 1843, the Eastern Caribbean was affected by the biggest ever recorded earthquake. The region from St. Maarten to Dominica experienced very intensive damages. All masonry was destroyed and the earthquake also caused a big fire that destroyed a lot of wooden structures in Antigua. The estimated number of deaths is about 4000-6000 people, which represents 1/3 of the population. This earthquake was felt as far south as Caracas and British Guiana and was even felt in Washington, which is 2000 km away.The magnitude of this earthquake is estimated to have a range of 8. 0-8. 5. On January 12, 2010, a 7. 3 magnitude strong earthquake happened in Haiti, the capital Port-au-Prince. The World Health Organization confirmed that the Haiti earthquake resulted in 222,500 death and 196,000 more injured. The epicenter was 15 kilometers from the Haitian ca pital, Port-au-Prince. According to the preliminary estimates of the International Committee of the Red Cross, this devastating earthquake will result in 3 million Haitian refugees.

A Guide to a Social Work and Human Services Research Paper

A Guide to a Social Work and Human Services Research Paper A ‘research paper’ is the phrase, which evokes anxiety and depression among students. Learners realize that they will have to put many efforts and time into crafting their paper if they want to get a high mark and impress their groupmates with surprising findings. An individual should be able to organize the writing process and complete all parts of the research paper to reach the desired result and contribute to the field with his/her findings. The following social work research paper guide will be helpful when you do not know how to start or stuck with a particular part of your work. Pre-Writing Tips from Our Academic Writers At this point you should clearly understand the difference between a research proposal and a research paper. Although these two works are interconnected, they differ much in lengths, content, structure, goals, etc. The writing process is similar as you will have to gather information on the problem, select a topic for your research and analyze it using a particular framework. However, the primary purpose of the research proposal is to introduce the issue and convince the audience that the study worth conducting. This paper is similar to a pitch as you will have to engage the audience and motivate them to focus on your issue. Besides, you will formulate your research goals and describe what you are going to investigate in your study. On the contrary, the research paper is a finished project in which you present all the details of your work and tell about the main findings. In this study, you should expand on the topic, explain your position on the issue and introduce the results of th e study. There are a set of features, which set a research paper apart from the research proposal: A research paper is approximately a 10-pages document, but the lengths of the paper might differ greatly depending on the topic, methodology, the audience, type of the study, etc.; A research proposal is shorter as it should only introduce the problem and convince the reader that it is worth studying; A research paper should be backed up with 8-15 credible sources, so you will need to carry out an in-depth investigation of the problem; A research paper presents the results of the study and describes all the details. These features might help you to differentiate between two documents and correctly structuralize your study. It is essential to understand the central singularities between to work to craft a perfect paper and get the highest mark. How to Select the Social Work Research Paper Topic In most cases, students are assigned a particular topic, which they should develop and investigate in their study. In this case, you can skip this point and come to the research process. It is essential to gather more information to make the work exciting and insightful. Nevertheless, some instructors want their learners to conduct an investigation and collect more data on the issue. On the one hand, a student can look into the field of Social Work and gather information about relevant problems and existing solutions. At the same time, the writing process might become more challenging and time-consuming as a learner will have to focus on different fields, develop options, weigh up alternatives and decide on the best topic for the paper. In this case, it is possible to make a list of the most relevant and actual problems in the community and choose the one, which will meet your interests and preference. Furthermore, you might think about your profession and pick up the issue, which yo u might face at work. In such a way, you may develop practical solutions, which you will be able to apply in the real-life situations. If you run out of ideas, you may select a topic from the following list: The Impact of the Affordable Care Act on Social Wellbeing; Early Intervention in Special Education and its Effect on the Life of Troubled Families; Trauma Grief and Loss among Veterans; Intervention Techniques for Adopted Children; Diversity and its Effect on US and Canadian Communities; An Interconnection between Increased Crime Rate and Drug Addictions; Protection of Children’s Rights in Muslim Countries; Generation Gap and its Effect on Culture; Social Services for Refugees; Innovative Counseling Techniques for Individuals with Disabilities, etc. Deep Dive in the Research Process: Key Points Before you start writing your paper, it is vital to gather more information on the topic and get a better understanding of the Social Work and Human Services field. The stage is essential since it will provide you with the necessary data and help to establish the foundation for your study. The research process might assist you with the following tasks: Understand your subject; Find the problematic areas and focus on them; Select a relevant and exciting topic for your paper; Develop a persuasive thesis statement; Discuss the issue with the authority and gather primary data from your groupmates or an instructor. The first step is to find resources, review it and analyze it. Nonetheless, you should be careful about selecting the sources for your paper as some of them might be incredible, which will negatively affect the value of your study. You might use for the following resources and incorporate them in your research paper: Google Scholar; Online Encyclopedias and databases: Scientific Journals; Newspapers; State publications; Official reports, etc. Identify the keywords in your topic and search for the available information on the Internet. In such way, you will see whether your problem is relevant to the community. Additionally, you will have a chance to look at the findings of renowned scholars and analyze their solutions to a problem. Develop an Outline before You Start Writing When you conducted a study and gained basic knowledge about the sphere, you might already have the ideas for your research paper. You can develop an outline where you will include all the components of the work and incorporate your arguments. At this stage, it is significant to identify your position on the issue, which will tie up all the parts of your research paper since it will help you to develop an effective thesis statement. Identify the Goal of the Study You should write the primary goal of your study and make sure that it is realistic, attainable, specific and measurable. For example, the aim â€Å"to resolve the problem of homelessness† is not suitable for the research paper as your investigation will not help to address the issue in the global perspective. Instead, you should focus on realistic outcomes of you study, such as: Investigate the positive and negative effects of health care reforms on the community; Develop a smart solution to the problem of homelessness; Evaluate the impact of innovation on the social work field; Analyze the legal framework of social work in the United States and offer a set of amendments to the documents; Identify the central issues in special education; Analyze the effect of corporate social responsibility projects on the wellbeing of the society, etc. These goals are attainable since you can achieve them in the scope of your study. Moreover, they are specific since they will let you focus on a particular problem and develop a discussion. Besides, these goals are realistic as you will be able to come up with a new solution and contribute to the development of the Social Work and Human Services field. Writing Tips You Must Follow Introduction. In this part, you should present the background to your study and provide necessary information about the problem. It is an excellent idea to craft a strong opening sentence, which will quickly grab readers’ attention and engage them in the discussion. Individuals should be interested in reading the whole paper and look at the findings of your study. You might start with impressive statistics or a shocking fact, which will speak about the significance of the issue for the modern community. If you write a research paper, it does not mean that it should be boring. After that, you can state the primary purpose of your study and formulate the goal of the research. Explain how you organized your paper and what parts you want to include in the work. Finalize with a persuasive thesis statement, which will present your position on the topic and encourage readers to accept your point of view. You should cover the following steps in your introductory paragraph: Create the context of the study; Formulate the primary goal of the research and explain its value for the audience; Conclude with a thesis statement. Main Body. You can use your outline here and include all your arguments in this part. The content of the main body is highly dependent on the type of your research and methods used. First, you can conduct a literature review and analyze the findings of other scholars. This step will help you to understand the field and provide readers with essential information on the topic. At this stage, you should identify the gap in the study and concentrate on the problem, which requires your attention. After that, you should write methodology and determine the methods and techniques, which you will apply in your research. Think over the steps, which will help you to get more data and investigate the topic in-depth. For instance, you can use interviews or questionnaires to obtain primary data, which will significantly help you in the research process. However, in this case, you will have to think over the target audience and their rights. Store the data on secure websites and databases to preven t leakages and disclosures, which will negatively affect your study and reputation. After you analyzed the previous works and obtained results, you can come to the discussion and list your main findings. It is an excellent idea to contrast your results with other scholars as it would help you to look at the problem from different perspectives and come to objective conclusions. Conclusion. Now, it is the time to summarize your findings and finalize the research paper. The majority of students restate the thesis statement, which helps reads to remind about your goal and position on the topic. However, you must not copy paste the sentence from your introduction and insert it in the conclusion section. Persuasively reword your thesis statement and encourage readers to think over the problem. Additionally, you may identify the area for further research and explain why you feel scholars should continue investigating this topic. Post-Writing Tips: Final Touches That Matter Editing and Proofreading. After you developed the draft of your work, you should ensure that you do not have any mistakes or errors in your work. Your instructor might mark down your paper if he/she finds misprints. Therefore, it is better to give the document to your friend and ask him/her to read it. This step will help you to listen to other person’s opinion and make necessary corrections. Moreover, you can use software to check the paper for grammatical, spelling or stylistic mistakes. References. Cite your sources correctly and pay attention to the format of your paper. You should follow the requirements and make sure that all books and articles are included in your work. However, every educational institution might have own standards, so it would be better to ask a professor to provide you with recommendations. The social work research paper tips listed above can simplify the writing and make it more joyful. Focus on your field and find interesting information that will grab readers’ attention. If you enjoy the research process and deep dive into the area, you are likely to get the highest mark and gain success with your social work research paper.