Two trains, one 153 m long and the other 127 m long; coming from opposite directions crossed each other in 7.2 seconds. The combined speed of the two trains every hour would then be: ?->(Show Answer!)

1. Two trains, one 153 m long and the other 127 m long; coming from opposite directions crossed each other in 7.2 seconds. The combined speed of the two trains every hour would then be:

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MCQ->Two trains, one 153 m long and the other 127 m long; coming from opposite directions crossed each other in 7.2 seconds. The combined speed of the two trains every hour would then be:....

MCQ-> In a modern computer, electronic and magnetic storage technologies play complementary roles. Electronic memory chips are fast but volatile (their contents are lost when the computer is unplugged). Magnetic tapes and hard disks are slower, but have the advantage that they are non-volatile, so that they can be used to store software and documents even when the power is off.In laboratories around the world, however, researchers are hoping to achieve the best of both worlds. They are trying to build magnetic memory chips that could be used in place of today’s electronics. These magnetic memories would be nonvolatile; but they would also he faster, would consume less power, and would be able to stand up to hazardous environments more easily. Such chips would have obvious applications in storage cards for digital cameras and music- players; they would enable handheld and laptop computers to boot up more quickly and to operate for longer; they would allow desktop computers to run faster; they would doubtless have military and space-faring advantages too. But although the theory behind them looks solid, there are tricky practical problems and need to be overcome.Two different approaches, based on different magnetic phenomena, are being pursued. The first, being investigated by Gary Prinz and his colleagues at the Naval Research Laboratory (NRL) in Washington, D.c), exploits the fact that the electrical resistance of some materials changes in the presence of magnetic field— a phenomenon known as magneto- resistance. For some multi-layered materials this effect is particularly powerful and is, accordingly, called “giant” magneto-resistance (GMR). Since 1997, the exploitation of GMR has made cheap multi-gigabyte hard disks commonplace. The magnetic orientations of the magnetised spots on the surface of a spinning disk are detected by measuring the changes they induce in the resistance of a tiny sensor. This technique is so sensitive that it means the spots can be made smaller and packed closer together than was previously possible, thus increasing the capacity and reducing the size and cost of a disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather spinning disks. In a conventional memory chip, each binary digit (bit) of data is represented using a capacitor-reservoir of electrical charge that is either empty or fill -to represent a zero or a one. In the NRL’s magnetic design, by contrast, each bit is stored in a magnetic element in the form of a vertical pillar of magnetisable material. A matrix of wires passing above and below the elements allows each to be magnetised, either clockwise or anti-clockwise, to represent zero or one. Another set of wires allows current to pass through any particular element. By measuring an element’s resistance you can determine its magnetic orientation, and hence whether it is storing a zero or a one. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. Unlike the elements of an electronic memory, a magnetic memory’s elements are not easily disrupted by radiation. And compared with electronic memories, whose capacitors need constant topping up, magnetic memories are simpler and consume less power. The NRL researchers plan to commercialise their device through a company called Non-V olatile Electronics, which recently began work on the necessary processing and fabrication techniques. But it will be some years before the first chips roll off the production line.Most attention in the field in focused on an alternative approach based on magnetic tunnel-junctions (MTJs), which are being investigated by researchers at chipmakers such as IBM, Motorola, Siemens and Hewlett-Packard. IBM’s research team, led by Stuart Parkin, has already created a 500-element working prototype that operates at 20 times the speed of conventional memory chips and consumes 1% of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminium oxide just four or five atoms thick. The polarisation of lower magnetisable layer is fixed in one direction, but that of the upper layer can be set (again, by passing a current through a matrix of control wires) either to the left or to the right, to store a zero or a one. The polarisations of the two layers are then either the same or opposite directions.Although the aluminum-oxide barrier is an electrical insulator, it is so thin that electrons are able to jump across it via a quantum-mechanical effect called tunnelling. It turns out that such tunnelling is easier when the two magnetic layers are polarised in the same direction than when they are polarised in opposite directions. So, by measuring the current that flows through the sandwich, it is possible to determine the alignment of the topmost layer, and hence whether it is storing a zero or a one.To build a full-scale memory chip based on MTJs is, however, no easy matter. According to Paulo Freitas, an expert on chip manufacturing at the Technical University of Lisbon, magnetic memory elements will have to become far smaller and more reliable than current prototypes if they are to compete with electronic memory. At the same time, they will have to be sensitive enough to respond when the appropriate wires in the control matrix are switched on, but not so sensitive that they respond when a neighbouring elements is changed. Despite these difficulties, the general consensus is that MTJs are the more promising ideas. Dr. Parkin says his group evaluated the GMR approach and decided not to pursue it, despite the fact that IBM pioneered GMR in hard disks. Dr. Prinz, however, contends that his plan will eventually offer higher storage densities and lower production costs.Not content with shaking up the multi-billion-dollar market for computer memory, some researchers have even more ambitious plans for magnetic computing. In a paper published last month in Science, Russell Cowburn and Mark Well and of Cambridge University outlined research that could form the basis of a magnetic microprocessor — a chip capable of manipulating (rather than merely storing) information magnetically. In place of conducting wires, a magnetic processor would have rows of magnetic dots, each of which could be polarised in one of two directions. Individual bits of information would travel down the rows as magnetic pulses, changing the orientation of the dots as they went. Dr. Cowbum and Dr. Welland have demonstrated how a logic gate (the basic element of a microprocessor) could work in such a scheme. In their experiment, they fed a signal in at one end of the chain of dots and used a second signal to control whether it propagated along the chain.It is, admittedly, a long way from a single logic gate to a full microprocessor, but this was true also when the transistor was first invented. Dr. Cowburn, who is now searching for backers to help commercialise the technology, says he believes it will be at least ten years before the first magnetic microprocessor is constructed. But other researchers in the field agree that such a chip, is the next logical step. Dr. Prinz says that once magnetic memory is sorted out “the target is to go after the logic circuits.” Whether all-magnetic computers will ever be able to compete with other contenders that are jostling to knock electronics off its perch — such as optical, biological and quantum computing — remains to be seen. Dr. Cowburn suggests that the future lies with hybrid machines that use different technologies. But computing with magnetism evidently has an attraction all its own.In developing magnetic memory chips to replace the electronic ones, two alternative research paths are being pursued. These are approaches based on:
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MCQ-> Before the internet, one of the most rapid changes to the global economy and trade was wrought by something so blatantly useful that it is hard to imagine a struggle to get it adopted: the shipping container. In the early 1960s, before the standard container became ubiquitous, freight costs were I0 per cent of the value of US imports, about the same barrier to trade as the average official government import tariff. Yet in a journey that went halfway round the world, half of those costs could be incurred in two ten-mile movements through the ports at either end. The predominant ‘break-bulk’ method, where each shipment was individually split up into loads that could be handled by a team of dockers, was vastly complex and labour-intensive. Ships could take weeks or months to load, as a huge variety of cargoes of different weights, shapes and sizes had to be stacked together by hand. Indeed, one of the most unreliable aspects of such a labour-intensive process was the labour. Ports, like mines, were frequently seething pits of industrial unrest. Irregular work on one side combined with what was often a tight-knit, well - organized labour community on the other.In 1956, loading break-bulk cargo cost $5.83 per ton. The entrepreneurial genius who saw the possibilities for standardized container shipping, Malcolm McLean, floated his first containerized ship in that year and claimed to be able to shift cargo for 15.8 cents a ton. Boxes of the same size that could be loaded by crane and neatly stacked were much faster to load. Moreover, carrying cargo in a standard container would allow it to be shifted between truck, train and ship without having to be repacked each time.But between McLean’s container and the standardization of the global market were an array of formidable obstacles. They began at home in the US with the official Interstate Commerce Commission, which could prevent price competition by setting rates for freight haulage by route and commodity, and the powerful International Longshoremen's Association (ILA) labour union. More broadly, the biggest hurdle was achieving what economists call ‘network effects’: the benefit of a standard technology rises exponentially as more people use it. To dominate world trade, containers had to be easily interchangeable between different shipping lines, ports, trucks and railcars. And to maximize efficiency, they all needed to be the same size. The adoption of a network technology often involves overcoming the resistance of those who are heavily invested in the old system. And while the efficiency gains are clear to see, there are very obvious losers as well as winners. For containerization, perhaps the most spectacular example was the demise of New York City as a port.In the early I950s, New York handled a third of US seaborne trade in manufactured goods. But it was woefully inefficient, even with existing break-bulk technology: 283 piers, 98 of which were able to handle ocean-going ships, jutted out into the river from Brooklyn and Manhattan. Trucks bound‘ for the docks had to fiive through the crowded, narrow streets of Manhattan, wait for an hour or two before even entering a pier, and then undergo a laborious two-stage process in which the goods foot were fithr unloaded into a transit shed and then loaded onto a ship. ‘Public loader’ work gangs held exclusive rights to load and unload on a particular pier, a power in effect granted by the ILA, which enforced its monopoly with sabotage and violence against than competitors. The ILA fought ferociously against containerization, correctly foreseeing that it would destroy their privileged position as bandits controlling the mountain pass. On this occasion, bypassing them simply involved going across the river. A container port was built in New Jersey, where a 1500-foot wharf allowed ships to dock parallel to shore and containers to be lified on and off by crane. Between 1963 - 4 and 1975 - 6, the number of days worked by longshoremen in Manhattan went from 1.4 million to 127,041.Containers rapidly captured the transatlantic market, and then the growing trade with Asia. The effect of containerization is hard to see immediately in freight rates, since the oil price hikes of the 1970s kept them high, but the speed with which shippers adopted; containerization made it clear it brought big benefits of efficiency and cost. The extraordinary growth of the Asian tiger economies of Singapore, Taiwan, Korea and Hong Kong, which based their development strategy on exports, was greatly helped by the container trade that quickly built up between the US and east Asia. Ocean-borne exports from South Korea were 2.9 million tons in 1969 and 6 million in 1973, and its exports to the US tripled.But the new technology did not get adopted all on its own. It needed a couple of pushes from government - both, as it happens, largely to do with the military. As far as the ships were concerned, the same link between the merchant and military navy that had inspired the Navigation Acts in seventeenth-century England endured into twentieth-century America. The government's first helping hand was to give a spur to the system by adopting it to transport military cargo. The US armed forces, seeing the efficiency of the system, started contracting McLean’s company Pan-Atlantic, later renamed Sea-land, to carry equipment to the quarter of a million American soldiers stationed in Western Europe. One of the few benefits of America's misadventure in Vietnam was a rapid expansion of containerization. Because war involves massive movements of men and material, it is often armies that pioneer new techniques in supply chains.The government’s other role was in banging heads together sufficiently to get all companies to accept the same size container. Standard sizes were essential to deliver the economies of scale that came from interchangeability - which, as far as the military was concerned, was vital if the ships had to be commandeered in case war broke out. This was a significant problem to overcome, not least because all the companies that had started using the container had settled on different sizes. Pan- Atlantic used 35- foot containers, because that was the maximum size allowed on the highways in its home base in New Jersey. Another of the big shipping companies, Matson Navigation, used a 24-foot container since its biggest trade was in canned pineapple from Hawaii, and a container bigger than that would have been too heavy for a crane to lift. Grace Line, which largely traded with Latin America, used a foot container that was easier to truck around winding mountain roads.Establishing a US standard and then getting it adopted internationally took more than a decade. Indeed, not only did the US Maritime Administration have to mediate in these rivalries but also to fight its own turf battles with the American Standards Association, an agency set up by the private sector. The matter was settled by using the power of federal money: the Federal Maritime Board (FMB), which handed out to public subsidies for shipbuilding, decreed that only the 8 x 8-foot containers in the lengths of l0, 20, 30 or 40 feet would be eligible for handouts.Identify the correct statement:
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MCQ-> The broad scientific understanding today is that our planet is experiencing a warming trend over and above natural and normal variations that is almost certainly due to human activities associated with large-scale manufacturing. The process began in the late 1700s with the Industrial Revolution, when manual labor, horsepower, and water power began to be replaced by or enhanced by machines. This revolution, over time, shifted Britain, Europe, and eventually North America from largely agricultural and trading societies to manufacturing ones, relying on machinery and engines rather than tools and animals.The Industrial Revolution was at heart a revolution in the use of energy and power. Its beginning is usually dated to the advent of the steam engine, which was based on the conversion of chemical energy in wood or coal to thermal energy and then to mechanical work primarily the powering of industrial machinery and steam locomotives. Coal eventually supplanted wood because, pound for pound, coal contains twice as much energy as wood (measured in BTUs, or British thermal units, per pound) and because its use helped to save what was left of the world's temperate forests. Coal was used to produce heat that went directly into industrial processes, including metallurgy, and to warm buildings, as well as to power steam engines. When crude oil came along in the mid- 1800s, still a couple of decades before electricity, it was burned, in the form of kerosene, in lamps to make light replacing whale oil. It was also used to provide heat for buildings and in manufacturing processes, and as a fuel for engines used in industry and propulsion.In short, one can say that the main forms in which humans need and use energy are for light, heat, mechanical work and motive power, and electricity which can be used to provide any of the other three, as well as to do things that none of those three can do, such as electronic communications and information processing. Since the Industrial Revolution, all these energy functions have been powered primarily, but not exclusively, by fossil fuels that emit carbon dioxide (CO2), To put it another way, the Industrial Revolution gave a whole new prominence to what Rochelle Lefkowitz, president of Pro-Media Communications and an energy buff, calls "fuels from hell" - coal, oil, and natural gas. All these fuels from hell come from underground, are exhaustible, and emit CO2 and other pollutants when they are burned for transportation, heating, and industrial use. These fuels are in contrast to what Lefkowitz calls "fuels from heaven" -wind, hydroelectric, tidal, biomass, and solar power. These all come from above ground, are endlessly renewable, and produce no harmful emissions.Meanwhile, industrialization promoted urbanization, and urbanization eventually gave birth to suburbanization. This trend, which was repeated across America, nurtured the development of the American car culture, the building of a national highway system, and a mushrooming of suburbs around American cities, which rewove the fabric of American life. Many other developed and developing countries followed the American model, with all its upsides and downsides. The result is that today we have suburbs and ribbons of highways that run in, out, and around not only America s major cities, but China's, India's, and South America's as well. And as these urban areas attract more people, the sprawl extends in every direction.All the coal, oil, and natural gas inputs for this new economic model seemed relatively cheap, relatively inexhaustible, and relatively harmless-or at least relatively easy to clean up afterward. So there wasn't much to stop the juggernaut of more people and more development and more concrete and more buildings and more cars and more coal, oil, and gas needed to build and power them. Summing it all up, Andy Karsner, the Department of Energy's assistant secretary for energy efficiency and renewable energy, once said to me: "We built a really inefficient environment with the greatest efficiency ever known to man."Beginning in the second half of the twentieth century, a scientific understanding began to emerge that an excessive accumulation of largely invisible pollutants-called greenhouse gases - was affecting the climate. The buildup of these greenhouse gases had been under way since the start of the Industrial Revolution in a place we could not see and in a form we could not touch or smell. These greenhouse gases, primarily carbon dioxide emitted from human industrial, residential, and transportation sources, were not piling up along roadsides or in rivers, in cans or empty bottles, but, rather, above our heads, in the earth's atmosphere. If the earth's atmosphere was like a blanket that helped to regulate the planet's temperature, the CO2 buildup was having the effect of thickening that blanket and making the globe warmer.Those bags of CO2 from our cars float up and stay in the atmosphere, along with bags of CO2 from power plants burning coal, oil, and gas, and bags of CO2 released from the burning and clearing of forests, which releases all the carbon stored in trees, plants, and soil. In fact, many people don't realize that deforestation in places like Indonesia and Brazil is responsible for more CO2 than all the world's cars, trucks, planes, ships, and trains combined - that is, about 20 percent of all global emissions. And when we're not tossing bags of carbon dioxide into the atmosphere, we're throwing up other greenhouse gases, like methane (CH4) released from rice farming, petroleum drilling, coal mining, animal defecation, solid waste landfill sites, and yes, even from cattle belching. Cattle belching? That's right-the striking thing about greenhouse gases is the diversity of sources that emit them. A herd of cattle belching can be worse than a highway full of Hummers. Livestock gas is very high in methane, which, like CO2, is colorless and odorless. And like CO2, methane is one of those greenhouse gases that, once released into the atmosphere, also absorb heat radiating from the earth's surface. "Molecule for molecule, methane's heat-trapping power in the atmosphere is twenty-one times stronger than carbon dioxide, the most abundant greenhouse gas.." reported Science World (January 21, 2002). “With 1.3 billion cows belching almost constantly around the world (100 million in the United States alone), it's no surprise that methane released by livestock is one of the chief global sources of the gas, according to the U.S. Environmental Protection Agency ... 'It's part of their normal digestion process,' says Tom Wirth of the EPA. 'When they chew their cud, they regurgitate [spit up] some food to rechew it, and all this gas comes out.' The average cow expels 600 liters of methane a day, climate researchers report." What is the precise scientific relationship between these expanded greenhouse gas emissions and global warming? Experts at the Pew Center on Climate Change offer a handy summary in their report "Climate Change 101. " Global average temperatures, notes the Pew study, "have experienced natural shifts throughout human history. For example; the climate of the Northern Hemisphere varied from a relatively warm period between the eleventh and fifteenth centuries to a period of cooler temperatures between the seventeenth century and the middle of the nineteenth century. However, scientists studying the rapid rise in global temperatures during the late twentieth century say that natural variability cannot account for what is happening now." The new factor is the human factor-our vastly increased emissions of carbon dioxide and other greenhouse gases from the burning of fossil fuels such as coal and oil as well as from deforestation, large-scale cattle-grazing, agriculture, and industrialization.“Scientists refer to what has been happening in the earth’s atmosphere over the past century as the ‘enhanced greenhouse effect’”, notes the Pew study. By pumping man- made greenhouse gases into the atmosphere, humans are altering the process by which naturally occurring greenhouse gases, because of their unique molecular structure, trap the sun’s heat near the earth’s surface before that heat radiates back into space."The greenhouse effect keeps the earth warm and habitable; without it, the earth's surface would be about 60 degrees Fahrenheit colder on average. Since the average temperature of the earth is about 45 degrees Fahrenheit, the natural greenhouse effect is clearly a good thing. But the enhanced greenhouse effect means even more of the sun's heat is trapped, causing global temperatures to rise. Among the many scientific studies providing clear evidence that an enhanced greenhouse effect is under way was a 2005 report from NASA's Goddard Institute for Space Studies. Using satellites, data from buoys, and computer models to study the earth's oceans, scientists concluded that more energy is being absorbed from the sun than is emitted back to space, throwing the earth's energy out of balance and warming the globe."Which of the following statements is correct? (I) Greenhouse gases are responsible for global warming. They should be eliminated to save the planet (II) CO2 is the most dangerous of the greenhouse gases. Reduction in the release of CO2 would surely bring down the temperature (III) The greenhouse effect could be traced back to the industrial revolution. But the current development and the patterns of life have enhanced their emissions (IV) Deforestation has been one of the biggest factors contributing to the emission of greenhouse gases Choose the correct option:....

MCQ-> Read the following passage carefully and answer the question given below it. Certain words/phrases have been printed in bold to help you locate them while answering some of the questions. There was a country long time ago where the people would change a king every year. The person who would become the king had to agree to a contract that he would be sent to an island after one year of his being a king. One King had finished his term and it was time for him to go to the island and live there.The people dressed him up in expensive clothes and put him on an elephant and took him to around the cities to say goodbye to all the people. This was a moment of sadness for all kings who ruled for one year. After bidding farewell the people took the king to a remote island in a boat and left him there. On their way back they discovered a ship that had sunk just recently.They saw a young man who survived by holding on to a floating piece of wood. As they needed a new king, they picked up the young man and took him to their country. They requested him to be king for a year. First he refused but later he agreed to be the king. People told him about all the rules and regulations and about how he would be sent to an island after one year. After three days of being a king he asked the ministers if they could show him the island where all the other kings were sent. They agreed and took him to the island. The island was covered with a thick jungle and sounds of vicious animals were heard coming out of it. The king went a little bit further to check. Soon he discovered dead bodies of all the past kings.He understood that as soon as they were left on the island the wild animals had come and killed them. The king went back to the country and collected 100 strong workers. He took them to the island and instructed them to clean the jungle, remove all the deadly animals and cut down all excess trees. He would visit the island every month to see how the work was progressing. In the first month all the animals were removed and many trees were cut down. In the second month all the island were cleaned out. The king then told the workers to plant gardens in various parts of the island. He also took with himself useful animals like chickens, ducks, birds, goats,cows etc. In the third month he ordered the workers to build big house and docking stations for ships. Over the months the island turned into a beautiful place. The young king would wear simple clothes and spend very little from his earning as a king. He sent all the earnings to the island for storage. When nine months passed like this the king called the ministers and told them “I know that I have go to the island after one year but I would like to go there right now. But the ministers didn’t agree to this and said that he had to wait for another three months to complete the year. Three months passed and now it was a full year. The people dressed up the young king and put on an elephant to take him around the country to say goodbye to others. However this king was unusually happy to leave the kingdom. People asked him "All the other kings would cry at this moment. Why is it that you are laughing?". He replied “Don’t you know what the wise people say? They say that when you come to this world as a baby you are crying and everyone else is smiling. Live such a life that when you die you will be smiling and everyone around you will be crying. I have lived that life. While all the other kings were lost into the luxuries of the kingdom, I always thought about the future and planned for it. I turned the deadly island into a beautiful abode for me where I can stay peacefully”.Why did the people of the kingdom change the king every year ?
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