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have a look at
http://www.goiit.com/posts/list/games-puzzles-and-quizzes-cool-facts-gain-some-knowledge-41865.htm
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well i have not taken them in phase. there is phase difference- wt-kx-(wt+kx)=-2kx.
talking of phase difference of pie it doesnot need be taken here as we are considering two different waves of same frequency travelling in opposite direction and not one wave which forms a standing wave after reflection from a rigid support.
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y1=Asin(wt-kx)
y2=Asin(wt+kx) [travelling in opp. direction]
using principle of superposition--
y=y1+y2
=A[sin(wt-kx)+sin(wt+kx)]
=2Asin(wt)cos(kx)
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well the nature of image does not vary.
the only thing that has to be done is to consider the cut part as a normat convex lens and then solve.
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The Speed of Light Most people usually think of the speed of light as being really fast. It's 671 million miles per hour. That seems tantalizingly zippy if you're caught in traffic. However, once you think about the speed of light within the context of our solar system, it starts to seem unimpressive. It takes about 1.3 seconds for light or radio waves to reach us from the Moon, which really isn't all that far away (it's only 20 times farther away than Australia is to the United States). This was an issue during the Apollo space program, because due to the round trip time of the radio signals, NASA had to wait about three seconds to hear the answer to every question they asked the astronauts. When Mars is closest to the Earth, it takes light three minutes to travel between the two planets. If you asked a question to an astronaut on Mars, you'd have to wait at least six minutes for an answer, and Mars is usually a lot farther away than that. At its greatest distance, you'd have to wait 42 minutes, or even longer if the astronaut is watching Gilmore Girls. In the future, there will be no such thing as sending an "instant message" to your friends on the Mars base. There also won't be any day trading or free pizza delivery. The Voyager 1 spacecraft was launched only 29 years ago. It's currently the farthest away from the Earth of any man-made object. In just a short amount of time, this spacecraft, designed by primitive 1970's-era engineers, many of whom were wearing corduroy bell bottoms, has managed to travel so far away from the Earth that it takes radio signals travelling at the speed of light 14 hours to reach it. I am not making this up. An object that was recently built by people is now far enough away that if you could travel to it at the speed of light, for the in-flight movie you could watch the original director's cut of Water World four times, break for a dinner, and then watch Ishtar before having to put your tray in its upright position. Light takes four and half years to travel to the nearest star (other than the Sun), 100,000 years to travel across the width of the galaxy, and 100 billion years to travel across the observable Universe.
The speed of light isn't all that fast. Get over it. Source:internet
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A cockroach can survive for about a week or so without its head! If a cockroach becomes decapitated, the wound on their neck would clot and seal off. If this happens they will no longer be able to eat food, but insects can survive for weeks on only one meal. Without a brain, cockroaches can still perform simple bodily functions and simple reactions. Cockroaches have existed on Earth for about 350 million years. This amazing feature of cockroaches shows the endurance that they have gained over their existence. Their head can even survive for a few hours after being cutting off.
Source:internet
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 Hoba Meteorite The Hoba meteorite is the largest to ever have been found on Earth. The Hoba meteorite was found in Namibia, Africa in 1920. This meteorite, which landed some 80,000 years ago, is composed of iron and weighs a hefty 60,000 kg. It still lies in its original resting spot in Namibia, Africa. The Williamette meteorite found in Oregon is the largest meteorite found in the United States. It was found in 1902 in the Williamette Valley of Oregon. It is now on display at the American Museum of Natural History.
Source:internet
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SCIENTIFIC PROOF OF EXISTENCE OF GOD According to Oxford dictionary science is a branch of knowledge requiring systematic study and method, esp. dealing with substances, life, and natural laws. So science categorizes everything, which exists as known, unknown and unknowable. Known is the science, unknown is that on which scientists work and will be known in due course of time and there is nothing such as unknowable in the field of science. According to the scientists there can?t be any mystery in this world and sooner or later the science has the capability to reveal that mystery by using scientific methods. The scientific community tries to create scientific temperament among the general masses by asking the people to inquire about everything that exists and asks them to reject those things which does not have RATIONAL explanation. Believe in what you can see (e.g. light), feel (e.g. your body) and hear (e.g. sound vibration). To be more precise scientists assert that believe only on your senses, that which can be perceived by our senses is scientifically possible, is rational otherwise it is a myth and should be discarded as blind faith. Should a scientist believe in God? The question, which have always baffled the scientific community and the common people. God cannot be perceived by our senses and till now there has been no scientific instrument, which can detect the presence of God in the cosmos. The common answer, which one generally gets from most of the people, is that Religion is FAITH and Science is REALITY.
One of my friend has no hesitation in accepting God, instead he minced no words in criticising the scientists who deny the existence of God. He did not believe in Big-Bang theory because according to him the theory cannot be proved experimentally. He believed in the existence of some supernatural power who controls everything .He justified his point by giving the example of Mother Teresa who healed one patient.
But the other friend of mine was not convinced. He was ready to accept GOD if God Himself comes and proves His existence. I love my mother because I can feel her and I do not love God because I can?t feel Him was his instant reply. Most of the people irrespective of their religion are sure about one thing,
They have faith in God, though there is no scientific proof. They believed in God because many others believed. Faith is to accept without inquiring, put trust without probing and acknowledge without prying. In other words Religion or accepting God or believing in some supernatural power is considered to be irrational which is based on some wild imagination. Is accepting God really irrational? Do science have the potential to explain everything that exists in the entire cosmos? Does science does not make any assumptions?
1) TIME-WHAT IS IT?
Though the reality of time, especially in the form of its effect on us is undeniable, time is one among the many fundamental truths of life that defy scientific definition. Be that as it may, we measure time by the movement of the cosmic bodies. As per current scientific understanding, one year is the time in which the earth completes one revolution around the sun. For an object orbiting continuously in a circular path, no point on the orbit can be considered special. So scientifically there?s nothing ?New? when we celebrate the New Year; the earth is going to continue in its same old path! Moreover no one can see, feel, smell, taste and hear TIME i.e. we cannot perceive time with our senses, yet no one can deny its existence. 2) Mathematicians throughout the world work with an imaginary number, which is the square root of minus 1.Important branches of mathematics ?for example, the theory of analytical function ?, are based on this imaginary unit. Without the help of this branch of mathematics, various complex theories and problems cannot be solved. Thus the existence of this number cannot be denied, yet there is no experimental proof of its existence. 3) Another scientific theory that is beyond the limit of experimental science is
Heisenberg?s uncertainty principle .In mathematical language, it is stated that the product of the uncertainties in the measured values of the position and momentum (product of mass and velocity) cannot be smaller than Plank?s constant. No existing experimental technique can prove this principle. However, scientists all over the world accept this statement as fact, knowing that the experimental proof is beyond their ability. 4) Similarly there is no scientific experiment to prove the Third Law Of Thermodynamics. This law as formulated by Planck, states that the entropy of a perfect crystal at absolute zero degrees is equal to zero. Factually there is no means available for measuring directly the absolute entropies. Therefore the proof of this law is beyond the realm of experimental science. PROOF OF GOD?S EXISTENCE. Sir Isaac Newton had a small scale model of solar system which was placed on a table in his room .The model was perfectly designed and
Everything rotated and orbited when a crank was turned. When one of his friend show it he immediately inquired about the artisan who had made it so beautiful. Newton with all seriousness replied, the previous night some explosion took place in my house
And this solar system was formed. The friend was not at all amused. Finally Newton explained,? You refuse to believe that this puny contraption came about by chance and yet you are convinced that the great original, the actual solar system, of which this mechanism is only a model has come into being without either a designer or a maker. Now tell me, by what sort of reasoning do you reach such an absurd conclusion. Everything we use has a designer. Someone designed a pen, a wristwatch or the china wall ?all; they never popped up by chance. Several trains, aeroplanes move in a well-coordinated manner and reach their destination without any difficulty ?all these are possible because of well-coordinated controlling system.
The giant sequoia tree develop and grows over 300 feet high with a diameter of unto 36feet from a tiny seed which is not bigger than the size of a pinhead. Obviously all these things are happening as per the laws of nature, but can there be any law without a lawmaker? The very presence of a law implies the presence of a lawmaker who imposes the law. Even a simple road sign that regulates traffic has an originator and a controller. What then of the great comprehensive laws that governs this entire universe? Such brilliantly conceived laws surely bear witness to a brilliant lawmaker.
As Srila Prabhupad the founder Acharya of International Society Of Krishna Consciousness (ISKCON) would say that any human being with a little common sense can understand the presence GOD.
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7/10
not believe completely
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pls rate if you like them.
i'll post more whenever i can.
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Orville and Wilbur Wright are historical figures because of their pioneering work in aviation and the fact that they built and flew the first successful airplane, the Kitty Hawk. The amazing thing was that both Orville and Wilbur were not researchers or aeronautical engineers but simply mechanics who ran a bicycle shop in Daytona, Ohio. After opening the shop in 1892, they designed their own bike called the Van Cleve. The bicycle shop paid the bills while they pursued their dream of conquering the skies. The Wright brothers studied basic aeronautical books and constructed various airplane wings and prototypes before they finally created the successful Kitty Hawk which was constructed with huge 8 foot propellers and even had its own unique lightweight engine that produced around 12 horsepower and weighed just 152 pounds. Despite the many counter claims and disputes over the Wright brothers title of the inventors of airplanes there is no doubt that what they achieved in their time was awesome by any standards.
Source:internet
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Trees
What are trees made out of? If you had asked me yesterday, I would have guessed that trees absorb raw materials from the ground through their roots, and use them to build new branches and roots as the tree grows. Or, perhaps trees are constructed by hardworking but underpaid gnomes and fairies during the night. As it happens, that's not the case. Although roots take up a small amount of important nutrients, the majority of the mass of a tree is created from carbon dioxide absorbed from the air by the tree's leaves. That's right. It sounds crazy, but trees are mostly made out of air, and fairies aren't even involved. When you burn wood, you're just dumping all that carbon dioxide back into the air where it originally came from. Don't do that. It annoys the fairies.
Source:internet
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Sleep If you were to live deep inside a cave, with no exposure to the outside world, eventually you would start sleeping roughly every 24 hours and 18 minutes, instead of exactly every 24 hours. Under normal circumstances, our eyes sense light from the Sun, and our brains adjust to the standard 24 hour day, but we'd really always like to sleep that extra 18 minutes. Why is that? Scientists don't really know, but maybe it explains why everyone is so crabby all the time. Some completely blind people, who sense no light at all, naturally live on a 24 hour, 18 minute day, and slowly march their schedule around the clock, out of phase with everybody else. I'm speaking from personal experience when I say that it's pretty annoying when you have a blind neighbor who mows his lawn in the middle of the night. Our built-in tendency to live on a 24 hour, 18 minute day might seem to make sense if that was how long days were in the distant past, and the length of each day has been slowly speeding up. However, exactly the opposite is occurring. The length of each day has been gradually increasing, as the rotation of the Earth slows down because of the Moon's tidal forces. Half a billion years ago, days were 22 hours long. Four and a half billion years ago, they were six hours long. This didn't allow for a lot of variety in the television programming schedule. A need for a longer day might also make sense if we were all from Mars. (We're not. Most of us are not. Let's just say that all the important people you know are not. If you don't already know that you are, you're not. It's best if you don't bring this up with your parents. Forget I mentioned any of this.) On Mars, each day is 24 hours and 39 minutes long. Scientists working on the Spirit and Opportunity Mars rover projects initially lived on a schedule based on Mars days, because the solar-powered rovers could only operate during daytime on Mars. The scientists wore special Mars watches so they'd know what time it was there. After a few months of this, and always sleeping weird hours, they were all pretty grumpy. Eventually they switched to a more practical, Earth-based schedule. Sleeping in one continuous block during the night is an extremely recent development. Humans only started doing this when artificial lighting become readily available, and it was easier for everybody to stay up late. Before that, people tended to sleep in multiple chunks throughout the night, separated by periods of activity. Presumably, they would use this time to make trips to the ice box or watch crude infomercials performed by nocturnal travelling minstrels, which were quite popular during the Renaissance.
Source:internet
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Body Hair We have just as much hair all over our bodies as chimpanzees or monkeys or any other furry primate. Most of it is just very short and light. It's called "vellus hair" or "peach fuzz". I think it's bizarre that most of our thick hair is on the tops of our heads. Imagine if dogs looked like that! On second thought, maybe it's better if you don't imagine that. Research shows that we humans lost all our body hair through evolution about a million years before somebody finally figured out how to purchase clothes at one of the first primitive Walmarts. One theory says that we lost our all body hair in an attempt to avoid parasites like ticks, fleas, and lice, and that we've only kept the hair on our heads because other people think it's pretty. As proof, consider that you haven't seen many bald pregnant women. There is a very special kind of louse that only lives in human clothing. DNA tests indicate that it evolved from a louse that only lives in human hair, and that this happened about 42,000 to 72,000 years ago. So, that's probably roughly when clothes first went on sale. There are no special lice that live in any form of footwear, so DNA testing cannot solve the troubling mystery of exactly at what point in the past Hello Kitty themed socks were invented. Source:internet
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Space Shuttle OK here is the deal with the space shuttle. It has three rocket engines in the back, but there's absolutely no room inside for all the fuel it needs to launch itself up into space. All of that fuel is stored outside the shuttle, in the big brown cylinder, called the external tank. The tank containing all the rocket fuel weighs seven times more than the space shuttle itself! That's a lot of really heavy fuel, and the space shuttle engines aren't quite strong enough to push the combined weight of the shuttle and the big bloated external tank up off the ground. That's what the two long white solid rocket boosters strapped onto the sides of the external tank are for. They lift the tank! Fortunately, it was not necessary to strap an infinite series of smaller and smaller rockets to the sides of the solid rocket boosters. It is not widely known that just behind the main flight deck of the space shuttle is a small Starbucks adapted for use in zero gravity.
Source: internet
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latest:X Planes(page 4),[Discovery Launch Day and Leonid Meteor Shower(page 3)]
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gravitational potential is the work done in bringing a body of unit mass from infinity to a point within the gravitational field of earth. as gravitational force is attractive therefore negative work is done i.e. is work is obtained hence the negative sign.
also potential energy is the work done in bringing a body from infinity to a point within the gravitational field of earth. by the above concept only it is also negative.
another way of explaining the above is that any body in the earth's gravitational field is in a bound system. hence work has to be done on it to free it from the gravitational pull not to bring it in the influence of gravity.
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