AcharyaChanakya/simple-wikipedia huggingface dataset:
Even in ancient times, people developed calendars to keep track of the number of days in a year. They also developed sundials that used the moving shadows cast by the sun through the day to measure times smaller than a day. Today, highly accurate clocks can measure time in less than a billionth of a second. The study of time measurement is known as horology.
The SI (International Systems of Units) unit of time is one second, written as s. When used as a variable in mathematics, time is often represented by the symbol formula_1.
In Einsteinian physics, time and space can be combined into a single concept. For more on the topic, see space-time continuum.
In physics, a force is an interaction between "objects". It is called an interaction because if one object acts on another, its action is "matched" by a reaction from the other object. This idea is known as Newton's third law, where "action" and "reaction" are "equal and opposite" ("matched").
The "objects" are just the things the force acts between. Different forces act between different sorts of object. For example, gravity acts between objects with mass, like the sun and the earth. Another example is electromagnetic force, which acts between objects with charge, like an electron and the nucleus of an atom. "Gravity" and "electromagnetic force" are two examples of forces.
A force changes the state of an object (some physical quantity changes) or, strictly, the states of two objects, since the force is an interaction. For example, a force causes an affected object to be pushed or pulled in a certain direction. This changes the object's momentum. Forces cause objects to accelerate, add to the object's overall pressure, change direction, or change shape. The strength of a force is measured in Newtons (N). There are four fundamental forces in physics.
A force is always a push, pull, or a twist, and it affects objects by pushing them up, pulling them down, pushing them to a side, or by changing their motion or shape in some other way.
According to Newton's Second Law of Motion, the formula for finding force is:
where formula_2 is the force,
formula_3 is the mass of an object,
and formula_4 is the acceleration of the object.
This formula says that when there is a force on an object then it will move faster and faster.
If the force is weak and the object is heavy, then it will take a long time to increase the speed very much,
but if the force is strong and the object is light, then it will move a lot faster very quickly.
Gravity is an acceleration. Everything that has a mass is being pulled toward the Earth because of that acceleration. This pull is a force called weight.
One can take the equation above and change formula_4 to the standard gravity "g", then a formula about the gravity on earth can be found:
where formula_7 is the weight of an object,
and formula_9 is the acceleration due to gravity at sea level. It is about formula_10.
This formula says that when you know the mass of an object, then you can calculate how much force there is on the object because of gravity.
You must be on earth to use this formula. If you are on the moon or another planet, then you can use the formula but "g" will be different.
Force is a vector, so it can be stronger or weaker and it can also point in different directions.
Gravity always points down into the ground (if you are not in space).
Another equation that says something about gravity is:
formula_2 is force; formula_13 is the gravitational constant, which is used to show how gravity accelerates an object; formula_14 is the mass of one object; formula_15 is the mass of the second object; and formula_16 is the distance between the objects.
This equation is used to calculate how the earth moves around the sun and how the moon moves around the earth. It is also used to calculate how other planets, stars and objects in space move around.
The equation says that if two objects are very heavy then there is a strong force between them because of gravity.
If they are very far apart then the force is weaker.
Laboratory techniques
Laboratory techniques are the techniques of handling the various pieces of apparatus.
Ways to dissolve a solid in a liquid or to mix two liquids in a test tube:
The International System of Units is the standard modern form of the metric system. The name of this system can be shortened or abbreviated to SI, from the French name "Système International d'unités".
The International System of Units is a system of measurement based on 7 base units: the metre (length), kilogram (mass), second (time), ampere (electric current), Kelvin (temperature), mole (quantity), and candela (brightness). These base units can be used in combination with each other. This creates "SI derived units", which can be used to describe other quantities, such as volume, energy, pressure, and velocity.
The system is used almost globally. Only Myanmar, Liberia, and the United States do not use SI as their official system of measurement. In these countries, though, SI is commonly used in science and medicine.
The metric system was created in France after the French Revolution in 1789. The original system only had two standard units, the kilogram and the metre. The metric system became popular amongst scientists.
In the 1860s, James Clerk Maxwell and William Thomson (later known as Lord Kelvin) suggested a system with three base units - length, mass, and time. Other units would be derived from those three base units. Later, this suggestion would be used to create the centimetre-gram-second system of units (CGS), which used the centimetre as the base unit for length, the gram as the base unit for mass, and the second as the base unit for time. It also added the dyne as the base unit for force and the erg as the base unit for energy.
As scientists studied electricity and magnetism, they realized other base units were needed to describe these subjects. By the middle of the 20th century, many different versions of the metric system were being used. This was very confusing.
In 1954, the 9th General Conference on Weights and Measures (CGPM) created the first version of the International System of Units. The six base units that they used were the metre, kilogram, second, ampere, Kelvin, and candela. The seventh base unit, the mole, was added in 1971.
SI is now used almost everywhere in the world, except in the United States, Liberia and Myanmar, where the older imperial units are still widely used. Other countries, most of them historically related to the British Empire, are slowly replacing the old imperial system with the metric system or using both systems at the same time.
The SI base units are measurements used by scientists and other people around the world. All the other units can be written by combining these seven base units in different ways. These other units are called "derived units".
Derived units are created by combining the base units. The base units can be divided, multiplied, or raised to powers. Some derived units have special names. Usually these were created to make calculations simpler.
Very large or very small measurements can be written using prefixes. Prefixes are added to the beginning of the unit to make a new unit. For example, the prefix "kilo-" means "1000" times the original unit and the prefix "milli-" means "0.001" times the original unit. So one "kilometre" is 1000 metres and one "milligram" is a 1000th of a gram.
Lake Michigan
Lake Michigan is one of the five Great Lakes in North America. It has a surface area of . It is wide. Lake Michigan is the 5th largest lake in the world.
Lake Michigan is surrounded by the U.S. states of Indiana, Illinois, Wisconsin, and Michigan. It is the only Great Lake that is not partly in Canada. The largest city on the shore of Lake Michigan is Chicago.
The earliest time that people lived near the lake was 800 CE. The word "Michigan" originally meant the lake itself. It is believed to come from the Ojibwa word "mishigami" meaning "great water".
The first person to reach the deepest part of Lake Michigan was J. Val Klump. Klump reached the bottom with a submarine as part of a 1985 research expedition.
Twelve million people live along Lake Michigan's shores. They are mainly in the Chicago and Milwaukee areas.
Gas syringe
A gas syringe is a tool used in a laboratory. It is used to collect a gas or to measure the volume of a gas.
Simple systems can be settled in the laboratory to collect gas or to compress it. It is usually used to explain Gas Law.
In chemistry, a mixture is a substance that is made up of two or more simpler substances. These substances can be chemical elements or compounds. A mixture can be made of liquids, solids, or gases.
A mixture is not the same as a compound which is made of two or more atoms connected together. For instance, a mixture of the gases hydrogen and nitrogen contains hydrogen and nitrogen, not the compound ammonia which is made of hydrogen and nitrogen atoms.
A mixture where the different parts can be distinguished easily is called "heterogenous", one where this is not the case is called "homogeneous". A third form is called colloid.
If one substance in a mixture dissolves in the other, it is called a solution. For example, if sugar is put in water it forms a mixture, then dissolves to make a solution. If it does not dissolve, it would be called a suspension.
Solids can be mixtures also. Alloys are mixtures. Many kinds of soil and rock are mixtures of different minerals. Thus, a mixture is made of two or more elements and/or compounds which are not chemically combined.
Language family
Language families are groups of languages that are related to each other because they come from a common older language. The languages in such a family are similar in their vocabulary or structure.
For example, French and Spanish both come from Latin. Latin was spoken a long time ago, and some of the people who spoke it started to speak one way, saying, for example, for good: "bueno" while another group started saying "bon." Most words are said a little differently in Spanish and French, so the two are called different languages.
Most languages belong to a language family, but some languages do not. These languages are called Language isolates.
There also are constructed languages, like for example Esperanto. Constructed languages are made for different reasons: making a 'world language', for fun, for use in fiction, etc.
"Ethnologue" 22 (2019) lists these language families as "major". Each has at least 1% of all languages on Earth:
"Glottolog" 4.0 (2019) lists the following as the largest families, of 8494 languages:
Chess is a board game for two players. It is played in a square board, made of 64 smaller squares, with eight squares on each side. Each player starts with sixteen pieces: eight pawns, two knights, two bishops, two rooks, one queen and one king. The goal of the game is for each player to try and checkmate the king of the opponent. Checkmate is a threat ('check') to the opposing king which no move can stop. It ends the game.
During the game the two opponents take turns to move one of their pieces to a different square of the board. One player ('White') has pieces of a light color; the other player ('Black') has pieces of a dark color. There are rules about how pieces move, and about taking the opponent's pieces off the board. The player with white pieces always makes the first move. Because of this, White has a small advantage, and wins more often than Black in tournament games.
Chess is popular and is often played in competitions called chess tournaments. It is enjoyed in many countries, and is a national hobby in Russia.
Most historians agree that the game of chess was first played in northern India during the Gupta Empire in the 6th century . This early type of chess was known as "Chaturanga", a Sanskrit word for the military. The Gupta chess pieces were divided like their military into the infantry, cavalry, elephants, and chariots. In time, these pieces became the pawn, knight, bishop, and rook. The English words "chess" and "check" both come from the Persian word "shāh" meaning king.
The earliest written evidence of chess is found in three romances (epic stories) written in Sassanid Persia around 600. The game was known as "chatrang" or "shatranj". When Persia was taken over by Muslims (633–644) the game was spread to all parts of the Muslim world. Muslim traders carried the game to Russia and to Western Europe. By the year 1000 it had spread all over Europe. In the 13th century a Spanish manuscript called "Libro de los Juegos" describes the games of "shatranj" (chess), backgammon, and dice.
The game changed greatly between about 1470 to 1495. The rules of the older game were changed in the West so that some of the pieces (queen, bishop) had more scope, development of the pieces was faster, and the game more exciting. The new game formed the basis of modern international chess. Historians of chess consider this as the most important change since the game was invented.
The rules of chess are governed by the World Chess Federation, which is known by the initials FIDE, meaning "Fédération Internationale des Échecs". The rules are in the section "Laws of Chess" of the "FIDE Handbook". FIDE also give rules and guidelines for chess tournaments.
Chess is played on a square board divided into eight rows of squares called ranks and eight columns called files, with a dark square in each player's lower left corner. This is altogether 64 squares. The colors of the squares are laid out in a checker (chequer) pattern in light and dark squares. To make speaking and writing about chess easy, each square has a name. Each rank has a number from 1 to 8, and each file a letter from "a" to "h". This means that every square on the board has its own label, such as g1 or f5. The pieces are in white and black sets. The players are called White and Black, and at the start of a game each player has 16 pieces. The 16 pieces are one king, one queen, two rooks, two bishops, two knights and eight pawns.
Definitions: vertical lines are "files"; horizontal lines are "ranks"; lines at 45° are "diagonals".
Each piece has its own way of moving around the board. The "X" marks the squares where the piece can move.
Most pieces capture as they move. If a piece lands on an opponent's piece, the opposing piece is taken off the board. There are three special cases:
If a move is made which attacks the opposing king, that king is said to be 'in check'. The player whose king is checked must make a move to remove the check. The options are: moving the king, capturing the threatening piece, or moving another piece between the threatening piece and the king. If the player whose king is in danger cannot do any of these things, it is checkmate, and the player loses the game.
Once in every game, each king can make a special move, known as "castling". When the king castles, it moves two squares to the left or right. When this happens, the rook is moved to stand on the opposite side of the King. Castling is only allowed if all of these rules are kept:
"En passant" ('in passing' in French) is a special capture. It is only available when a pawn moves forward two squares past an opposing pawn on an adjacent file. The opposing pawn must be on the 5th rank from its own side. Then the opponent's pawn can capture the double-mover "as if it had only moved one square forward". This option is open on the next move only.
For example, if the black pawn has just moved up two squares from g7 to g5, then the white pawn on f5 can take it by "en passant" on g6. The "en passant" rule was developed when pawns were allowed to make their double move. The rule made it more difficult for players to avoid pawn exchanges and blockade the position. It kept the game more open.
When a pawn moves to its eighth rank, it must be changed for a piece: a queen, rook, bishop, or knight of the same color (player's choice). Normally, the pawn is "queened", but in some advantageous cases another piece is chosen, called 'under-promotion'.
Checkmates are rare in competitive chess. The most common ends are decisions made by one or both players.
The FIDE rules for competitive chess include all the above rules, plus several others.
If players wish to adjust a piece on the board, they must first say "J'adoube" (I adjust) or the equivalent. Apart from that, if a piece is touched it must be moved if possible. This is the 'touch and move' law. If no legal move is possible with the touched piece, the player must make a legal move with another piece. When a player's hand leaves a piece after moving it then the move is over and may not be changed (if the move was legal).
There are a few famous cases where players appeared to break this rule without being punished. The most famous example was by the then World Champion Garry Kasparov against Judit Polgar in a top-class tournament.
Competitive games of chess must be played with special chess clocks which time a player only when it is his/her turn to move. The essence is that a player has to make a certain number of moves in a certain total time. After moving, the player presses a button on the clock. This stops the player's clock, and start's the opponent's clock. Usually the clocks are mechanical, but some are electronic. Electronic clocks can be set to various programs, and they can count moves made.
The moves of a chess game are written down by using a special chess notation. This is compulsory for any competitive game. Usually algebraic chess notation is used. In algebraic notation, each square has one and only one name (whether you are looking from White's side of the board or Black's). Here, moves are written in the format of: initial of piece moved – file where it moved – rank where it moved. For example, Qg5 means "queen moves to the g-file and 5th rank" (that is, to the square g5). If there are two pieces of the same type that can move to the same square, one more letter or number is added to show the file or rank from which the piece moved, e.g. Ngf3 means "knight from the g-file moves to the square f3". The letter P showing a pawn is not used, so that e4 means "pawn moves to the square e4".
If the piece makes a capture, "x" is written before the square in which the capturing piece lands on. Example: "Bxf3" means "bishop captures on f3". When a pawn makes a capture, the file from which the pawn left is used in place of a piece initial. For example: exd5 means "pawn captures on d5."
If a pawn moves to its eighth rank, getting a promotion, the piece chosen is written after the move, for example e1Q or e1=Q. Castling is written by the special notations 0-0 for kingside castling and 0-0-0 for queenside. A move which places the opponent's king in check normally has the notation "+" added. Checkmate can be written as # or ++. At the end of the game, 1-0 means "White won", 0-1 means "Black won" and ½-½ is a draw.
In print, "figurines" (like those in diagrams, but smaller) are used for the pieces rather than initials. This has the advantage of being language-free, whereas the initials of pieces are different in every language. Typefaces which include figurines can be purchased by chess authors. Also, basic notes can be added by using a system of well-known punctuation marks and other symbols. For example: ! means a good move, !! means a very good move, ? means a bad move, ?? a very bad move (sometimes called a "blunder"), !? a creative move that may be good, and ?! a doubtful move. The purpose of these methods is to make publications readable in a wider range of countries. For example, one kind of a simple "trap" known as the Scholar's mate, as in the diagram to the right, may be recorded:
2. Qh5?! Nc6
3. Bc4 Nf6?? (3...Qe7 would prevent the mate, with 4...Nf6 next move)
4. Qxf7# 1-0
With figurines in place of the initials, this would be understood by players everywhere.
Players may not smoke in the playing area, but only in areas designated by the organiser. Mobile phones may not be used or even switched on. Players may not use any sources of advice, and may not analyse on any device. These and other matters are covered by the FIDE Laws on the conduct of the players.
Chess is an easy game to learn the moves, but a difficult game to master. Strategy is an important part of the game. First of all comes the "openings", about which a great deal is now known. The best-known move, the King's Pawn opening, is the white player moving his king's pawn on e2 forward two spaces to e4. Black can reply to that move in various ways.
The first moves of a chess game are called the "opening". A chess opening is a name given to a series of opening moves. Recognized patterns of opening moves are "openings" and have been given names such as the Ruy Lopez or Sicilian defence. They are listed in reference works such as the "Encyclopaedia of Chess Openings". There are dozens of different openings. They range from gambits, where a pawn, say, is offered for fast development (e.g. the King's Gambit), to slower openings which lead to a maneuvering type of game (e.g. the Réti opening). In some opening lines, the sequence thought best for both sides has been worked out to 20–30 moves, but most players avoid such lines. Expert players study openings throughout their chess career, as opening theory keeps on developing.
The basic aims of the opening phase are:
Players think, and chess databases prove, that White, by virtue of the first move, begins the game with a better chance. Black normally tries to equalise, or to get some counterplay.
The middlegame is the part of the game after most pieces have been developed. It is where most games are won and lost. Many games will end in resignation even before an endgame takes place.<ref name="H/W">Hooper D. and Whyld K. 1992. "The Oxford companion to chess". 2nd ed, Oxford University Press.</ref>
A middlegame position has a structure. That structure is determined by the opening. The simplest way to learn the middlegame is to select an opening and learn it well (see examples in English opening and French defence).
These are some things to look for when looking at a middlegame position:
Here is an example from the borderline between opening and middlegame. In the diagram to the left, White will operate mainly on the Q-side, and Black on the K-side.
White, to play, may wish to cope with Black playing 10...Nf4. He can do this by playing 10.g3, or by playing 10.Re1 so that if 10...Nf4 11.Bf1 will preserve the bishop (in this position an important defensive piece). Or maybe White will plough ahead with 10.c5, the key move on the Q-side.
ChessBase shows that the number of tournament games with these choices were:
The data base also shows that the overall results were significantly better for 10.Re1. What the player does is note the features on the board, and formulate a plan which takes the features into account. Then the player works out a sequence of moves. Of course, in practice, the opponent is interfering with the plan at every step!
The endgame (or "end game" or "ending") is the part of the game when there are few pieces left on the board. There are three main strategic differences between earlier parts of the game and endgame:
All endgame positions can be put into two camps. On the one hand are positions which may be won by force. On the other hand, are positions which are drawn, or which should be drawn. The ones that are drawn for certain may be legally drawn (mate could not happen) or drawn by chess experience (no sane defence could lose). All endgames in master chess revolve around the borderline between winning and drawing. Generally, once a 'textbook' drawn position is reached the players will agree a draw; otherwise they play on.
Endgames can be studied according to the types of pieces that remain on board. For example, king and pawn endgames have only kings and pawns on one or both sides and the task of the stronger side is to promote one of the pawns. Other endings are studied according to the pieces on board other than kings, e.g. rook and pawn versus rook endgame.
Basic checkmates are positions in which one side has only a king and the other side has one or two pieces, enough to checkmate the opponent's king. They are usually learned at the beginner stage. Examples are mate with K+Q v K; K+R v K; K+2B v K; K+B&N v K (this one is quite difficult).
There are two types of chess programs. One is to play against you; the other is to help you become a better player by learning more. The two types can be made to work together, though they have different functions.
Chess engines are computer systems that can play chess games against human opponents. Quite a number have been devised; they can play at master level, though their processes are quite different from a human being.
Fritz is a German chess program by Frans Morsch and Mathias Feist, published by ChessBase. It is the current market leader. There is also a different kind of Fritz called "Deep Fritz" that is made for multi-processing. The latest kinds of the consumer products are Deep Fritz 12 and Fritz 12. They came with reviews by Josh Waitzkin, who said that "Fritz is like a woman that you can't get with. It just drives (makes) you to think in ways you've never thought before".
Shredder, also a ChessBase product, is claimed to be the strongest engine at present.
Rybka, a product by Vasik Rajlich, is Shredder's main rival.
Chess databases do not actually play. They give access to the recorded history of master chess. There are two components. First, there is the software, which lets one search and organise the database material. Then there is the actual database, typically one to four million games.
In practice, databases are used for two purposes. First, for a player to train his/her ability at specific openings. Second, to look up specific opponents to see what they play, and prepare against them beforehand.
The existence of chess databases is one of the reasons young players can achieve mastery at an early age.
ChessBase is the biggest database, and widely used by masters. Although it can be used online, most users download the software and data onto their computer. If that computer happens to be a laptop, then they might take the laptop to tournaments, to help prepare for games. Players may not use computers or any other aid during games, but much preparation goes on behind the scenes. ChessBase has to be purchased, and it is not cheap.
This is a Dutch magazine for advanced players, which runs an on-line database called NicBase as part of its services. NicBase is free, and has over a million games.
Chessgames.com runs an on-line database of games. It is partly free, but requires registration. Full access to all its facilities is by a fairly modest subscription. It has over half a million games on its database.
There are websites which a player can join (for a fee) and play on line. In this case, the subscriber will play against other subscribers, not a computer. All standards of players are amongst the members, and various events are on offer at different rates of play. The two leaders in this market are:
These are endgames for improvers, based on reviews by John Watson.
Gold is a soft, dense, yellow metal. It is a chemical element. Its chemical symbol is Au. Its atomic number is 79. As a precious metal, it has been used for many thousands of years by people all over the world, for jewelry, and as money. Gold is important because it is rare, but also easier to use than other rare metals. It is also used to repair and replace teeth and in electronic equipment such as computers. The color of this metal is also called "gold".
Mining methods for gold are similar to other metals. Gold is so valued that the discovery of a new place to mine has sometimes caused a gold rush. The deepest workplaces for miners in the world are in South African gold mines.
Often, gold is found as a native metal. This means it is not part of an ore, and does not need smelting. It may be in large, pure nuggets but more often must be separated from other minerals and soil.
Most of the gold on Earth is deep inside the Earth's core because it is dense. Nearly all discovered gold was deposited on the surface by meteorites.
In chemistry, gold is chemical element 79, a transition metal in Group 11. It has an atomic weight of 199.966 a.m.u. Its symbol is Au, from the Latin word for gold, "aurum". It is a "noble metal" meaning it has low chemical reactivity.
Gold is very soft. It is malleable, meaning a goldsmith can hammer it into thin metal sheets. It is also ductile, which means it can be pulled into wire. When it is used in money or in jewelry, it is often alloyed with silver or some other metal to make it harder.
Most metals are gray in color. Gold is yellow because of the way its electrons behave. The only other metal in common use that has a non-gray color is copper. Caesium also has a gold-like color, but it is not commonly used as a metal because it reacts with water.
Gold is a fairly good electrical conductor, but not as good as copper or silver. Copper and brass electrical connectors, especially those used with computer and audio/video equipment, are often plated with gold for corrosion resistance.
Gold can mean that something or someone is very good or has done very well. A gold medal is often the given to the first-place winner in a race or other sports. Something that is in some way good may be given gold status.
Metallic gold is non-toxic, which is unusual for a heavy metal. Soluble gold compounds, however, are toxic to the liver and kidneys. Gold is non-flammable, even in a pure oxygen environment or when finely powdered. It does not react with most household or laboratory chemicals. Gold is commonly processed with cyanide, which is highly toxic. Most of the cyanide is destroyed in the production process, so it is not present in the final product, but it can be a hazard to workers in a gold processing plant. Since gold conducts electricity, gold jewelry should never be worn when working with electricity.
A century is a way to describe a length of time. One century is one hundred years. The ancient Romans used the word "centuria" to describe a group of about one hundred soldiers, organized into a single unit.
The Roman numeral for 100 is "C". The word for 100 in Latin is "centum".
A centenary is a celebration of something that happened 100 years ago. A bicentenary celebrates 200 years, a tercentenary 300 years.
A centenarian is someone who is 100 years old or more.
Centennial means something that happens every 100 years, or that lasts 100 years.
The kilogram is the base unit of mass in the International System of Units (SI). It is in widely used in science, engineering, and commerce worldwide. The kilogram is exactly the mass of one litre of water.
As of May 20, 2019, the definition of the kilogram is based on the Planck constant as .
There are attempts to define the kilogram in other ways. One example specifies a number of atoms of a certain substance (at a certain temperature).
One kilogram is a little more than 2.2 pounds. One tonne is one thousand kilograms. One litre of water weighs almost exactly one kilogram, at , at sea level. This was the basis of the definition of the gram in 1795.
In 1879, the piece of metal was made. It was officially chosen to be the kilogram in 1889. It was made of 90% platinum and 10% iridium. Those metals were chosen because they do not rust or corrode like most metals. It is stored in a vault at the BIPM in Sèvres, France. From 1795 to 1799, the unit of mass was not called "kilogram" but was called "grave".
The original kilogram is kept inside bell jars. Over time, dust can collect on it. Before it is measured, it is cleaned to get the original size.
The kilogram is a unit of mass. In normal language, measuring mass defines how "heavy" is something. This is not scientifically correct. Mass is an "inertial property". It measures the tendency of an object to stay at a given speed when no force acts on it.
Sir Isaac Newton's laws of motion contain an important formula: "F" = "ma". "F" is force. "m" is mass. "a" is acceleration. An object with a mass ("m") of one kilogram will accelerate ("a") at one meter per second per second when acted upon by a force ("F") of one newton. This about one-tenth the acceleration due to earth’s gravity.
The weight of matter depends on the strength of gravity. The mass of matter does not. The mass of an object is the same everywhere. Matter has invariant mass assuming it is not traveling at a relativistic speed with respect to an observer. According to Einstein’s theory of special relativity, the relativistic mass (apparent mass with respect to an observer) of an object or particle with rest mass "m" increases with its speed as "M"=γ"m" (where γ is the Lorentz factor). This effect is vanishingly small at everyday speeds, which are by orders of magnitude less than the speed of light, but becomes noticeable at very high speeds. For example, traveling at just 10% the speed of light with respect to an observer—exceedingly fast compared to everyday speeds (about )—increases an object’s relativistic mass just over 0.5%.
As regards the kilogram, relativity’s effect upon the constancy of matter’s mass is simply an interesting scientific phenomenon that has zero effect on the definition of the kilogram and its practical realizations.</ref> Objects are "weightless" for astronauts in microgravity. However, the objects still have their mass and inertia. Astronaut must use ten times as much force to accelerate a ten-kilogram object at the same rate as a one-kilogram object.
A common swing, as shown in the picture, can show the relationship of force, mass and acceleration. Someone could push an adult on the swing. The adult would accelerate slowly. They would only swing a short distance forward before the swing would change direction. If a child is sitting on the swing, then the child would swing forward faster and further.
The second (symbol: s), is a unit of time. There are around 60 seconds in a minute, 60 minutes in an hour, and 24 hours in a day. This tradition dates back to the Babylonian.
In science, a second is the time it takes for a caesium atom to vibrate 9,192,631,770 (around 9 billion) times. Scientists measure the second this way because the length of a day changes all the time. For example, when the dinosaurs lived, a day was about an hour shorter. Vibrations of atoms on the other hand always take the same time. This atomic second is also called the SI second.
Metric prefixes are frequently combined with the word "second" to denote subdivisions of the second, "e.g.", the millisecond (one thousandth of a second) and nanosecond (one billionth of a second). Though SI prefixes may also be used to form multiples of the second (such as “kilosecond”, or one thousand seconds), such units are rarely used in practice. More commonly encountered, non-SI units of time such as the minute, hour, and day increase by multiples of 60 and 24 (rather than by powers of ten as in the SI system).
One heartbeat of an adult at rest, will last about one second.
Under the International System of Units, the second is currently defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. This definition refers to a caesium atom at rest at a temperature of (absolute zero). The ground state is defined at zero magnetic field. The second thus defined is equivalent to the ephemeris second.
The international standard symbol for a second is s (see ISO 31-1)
1 international second is equal to:
There are 31,536,000 seconds in a common year, 31,622,400 seconds in a leap year, and 31,557,600 seconds in a Julian year
Originally, the second was known as a "second minute", meaning the second minute (i.e. small) division of an hour. The first division was known as a "prime minute" and is equivalent to the minute we know today. Third and fourth minutes were sometimes used in calculations.
The factor of 60 comes from the Babylonians who used a sexagesimal (base-60) numeral system. However, the Babylonians did not subdivide their time units sexagesimally (except for the day). The hour had been defined by the ancient Egyptians as either 1/12 of daytime or 1/12 of nighttime, hence both varied with the seasons. Greek astronomers, for example Hipparchus and Ptolemy, defined the hour as 1/24 of a mean solar day. Sexagesimally subdividing this mean solar hour made the second 1/86,400 of a mean solar day.
Greek time periods, for example the mean synodic month, were usually specified quite precisely because they were "calculated" from carefully selected eclipses separated by hundreds of years—individual "mean" synodic months and similar time periods cannot be measured. Nevertheless, with the development of pendulum clocks keeping "mean time" (as opposed to the "apparent time" displayed by sundials), the second became measurable. The seconds pendulum was proposed as a unit of length as early as 1660 by the Royal Society of London. The duration of a beat or half period (one swing, not back and forth) of a pendulum one metre in length on the Earth's surface is approximately one second.
In 1956 the second was defined in terms of the period of revolution of the Earth around the Sun for a particular epoch, because by then it had become recognized that the Earth's rotation on its own axis was not sufficiently uniform as a standard of time. The Earth's motion was described in Newcomb's Tables of the Sun, which provides a formula for the motion of the Sun at the epoch 1900 based on astronomical observations made between 1750 and 1892. The second thus defined is
This definition was ratified by the Eleventh General Conference on Weights and Measures in 1960. The "tropical year" in the definition was not measured, but calculated from a formula describing a tropical year which decreased linearly over time, hence the curious reference to a specific "instantaneous" tropical year. Because this second was the independent variable of time used in ephemerides of the Sun and Moon during most of the twentieth century (Newcomb's Tables of the Sun were used from 1900 through 1983, and Brown's Tables of the Moon were used from 1920 through 1983), it was called the ephemeris second.
When atomic clocks were made, they became the basis of the definition of the second, rather than the revolution of the Earth around the Sun.
Following several years of work, Louis Essen from the National Physical Laboratory (Teddington, England) and William Markowitz from the United States Naval Observatory (USNO) determined the relationship between the hyperfine transition frequency of the caesium atom and the ephemeris second. Using a common-view measurement method based on the received signals from radio station WWV, they determined the orbital motion of the Moon about the Earth, from which the apparent motion of the Sun could be inferred, in terms of time as measured by an atomic clock. As a result, in 1967 the Thirteenth General Conference on Weights and Measures defined the second of atomic time in the International System of Units (SI) as
The ground state is defined at zero magnetic field. The second thus defined is equivalent to the ephemeris second.
The definition of the second was later refined at the 1997 meeting of the BIPM to include the statement
The revised definition would seem to imply that the ideal atomic clock would contain a single caesium atom at rest emitting a single frequency. In practice, however, the definition means that high-precision realizations of the second should compensate for the effects of the ambient temperature (black-body radiation) within which atomic clocks operate and extrapolate accordingly to the value of the second as defined above.
Sometimes in role-playing games a second is used to refer to a small period of time or a single turn of combat. It is used as a standard moment of time, and does not necessarily refer to a real second, and could be shorter or longer depending on the scenario.
Orange (color)
Orange is a color. It is the combination of red and yellow.
Orange is the color of an orange fruit, which is where the name of the color comes from. Before the orange fruit was introduced to England in the 1500s, this color was called "yellow-red". The first recorded use of "orange" as a color name in English was in 1512, in the court of King Henry VIII.
Basque Country (greater region)
The Basque Country (Basque: Euskal Herria) is a region in Southwestern Europe that is within the borders of France and Spain.
It is the home of the Basque people. It is at the western end of the Pyrenees on the Bay of Biscay. Its boundaries are complicated, as it consists of seven districts: four within Spain and three within France.
No one knows when the Basques came to Europe. Many say that they have been in Europe since the Neolithic period at the end of the Stone Age, but others say that they were here even earlier.
The first written information about the Basque Country is from the Roman times, when the Basque people already spoke their own language. During the fall of the Western Roman Empire, the Basque Country was isolated from the invading Goths.
During the Muslim invasion of Southern Europe, the Basque Country split in two: the Castilian and the Navarrese lands. A war with France later split the Navarrese zone in two.
After the Reconquista, the Castilian Basque lands and Navarre became part of the new country: Spain. Since then, Basque people from the Spanish area of the Basque Country have had their own government and have fought to gain the northern part of the Basque Country from France.
Today, three of the Basque districts in Spain (Araba, Bizkaia, and Gipuzkoa) form the Autonomous Community of the Basque Country. The political unit is one of 17 autonomous communities in Spain.
The fourth Basque district in Spain (Navarra) is its own separate autonomous community of Spain.
The three districts in the North (French) Basque Country are Lapurdi (Labourd), Nafarroa Beherea (Basse-Navarre) and Zuberoa/Xiberoa (Soule).
The entire region has a surface area of 20,664 km (7978 sq mi). The Autonomous Community of the Basque Country has 7,234 km (2793 sq mi), and its population is about 2,000,000 - about 5% of the total population of Spain. Basque and Spanish are spoken, and its largest city is Bilbao although the capital is Vitoria-Gasteiz.
M-theory
M-theory is a new idea in small-particle physics that is part of superstring theory that was initially proposed by Edward Witten. The idea, or theory, often causes arguments among scientists, because there is no way to test it to see if it is true. If ever proven true, M-theory and string theory would mean big progress for science.
To understand M-theory one must first have some knowledge of string theory. For hundreds of years, scientists have thought that the simplest objects in the universe are points, like dots. String theory says that this is wrong and that the simplest objects in the universe are shaped like pieces of string. These strings are so small that even when looked at very closely they look like points. Each basic particle is created by the strings vibrating in different patterns. The reason scientists had not thought of this idea for so long is that strings are much harder to work with than points. They seem to break such rules as causality and special relativity, which says that information cannot travel faster than the speed of light.
String theory has been developed because of a very important problem that has existed for almost 100 years. Albert Einstein's theory that describes the universe on very large scales (it is called general relativity), and it disagrees with two theories that describe things on very small scales (they are called quantum mechanics and the standard model). There are also problems with the Standard Model: it includes about 20 numbers that seem to have no explanation; it has too many "basic particles" - some scientists think it needs to have fewer; and it does not include gravity, which is needed to explain weight.
Many of these problems can be solved by thinking of basic particles as strings. Now there is only one number with no explanation, which gives the size of the strings. String theory includes particles that cause gravity, called gravitons; finding this out delighted the scientists who work on string theory. So, string theory successfully brings General Relativity and Quantum Mechanics together.
But there are some problems with string theory. Normally, we think of the universe as having 4 dimensions, or "basic directions". 3 of these basic directions can be thought of as "up/down", "forward/backward" and "left/right". The other direction is time. String theory needs 10 basic directions.
These six other directions can be explained if they are "curled up", so they are much too small to see. For example, by following the path of a spiral, it is possible to go a great distance along it without moving very far. The 6 other directions can be thought of as tiny spirals - strings can move along them a great distance but not seem to move. This can be looked at as a mathematical trick—a trick that has little to do with the real world that can be seen and touched. Such tricks are allowed if they give a theory that can better tell us how things work.
Another problem with string theory is that there are 5 different versions of it. Each version allows different kinds of strings and says they work in different ways. String theory is supposed to be a "theory of everything" so there should be only one version, not 5. M-theory solves this problem.
In 1995 Edward Witten started what has been called the "Second Superstring Revolution" by introducing M-theory to the world. This theory combines the 5 different string theories (along with a previously abandoned attempt to unify General Relativity and Quantum Mechanics called 11D-Supergravity) into one theory. What Witten actually did was to predict that the fact that all these different theories were connected was a result of there being some underlying theory of which they were all approximations. This theory is somewhat vague in nature and has not yet been pinned down.
Additionally, it was found that the equations that required string theory to exist in 10 dimensions were actually approximations as well. The proposed M-theory would need one extra dimension and instead be a theory that takes place in "11 dimensions". Witten has himself compared this idea in simple terms to a general who takes up a position on a hilltop, the extra space-coordinate, to get a better view of the battlefield's two other dimensions.
The combination is accomplished by knitting together a web of relationships between each of the string theories called dualities (specifically, S-duality, T-duality, and U-duality). Each of these dualities provides a way of converting one of the string theories into another. T-duality is probably the most easily explained of the dualities. It has to do with the size, written as R, of the curled up dimensions of the string theories. It was discovered that by taking a Type IIA string theory that has a size R and changing the radius to 1/R the result will end up being what is equivalent to a Type IIB theory of size R. This duality, along with the others, creates connections between all 5 (or 6, if supergravity is counted) theories. The fact that these dualities existed had been known before Witten came up with the idea of M-theory.
Additional amusement has come for many in guessing what the M might stand for (possibilities include Matrix, Magic, Muffin, Mystery, Mother and Membrane). Regardless of what the M might possibly mean, M-theory has become one of the most interesting and active areas of research in theoretical physics today.
"For a more technical explanation, see w:M-theory (simplified explanation)."
Jaguar Cars
Jaguar Cars is a brand of automobiles made by Jaguar Land Rover. This is a British car builder, owned by the Indian builder Cans Tata Motors since the beginning of 2008. It was established in 1922 by William Lyons. It was renamed Jaguar in 1935. Jaguar is owned by the Indian automobile manufacturer Tata Motors Ltd. Jaguar is known for its luxury saloons and sportscars.