182 résultats pour "energy"
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Automobile.
Electric motors have been used to power automobiles since the late 1800s. Electric power supplied by batteries runs the motor, which rotates a driveshaft, the shaftthat transmits engine power to the axles. Commercial electric car models for specialized purposes were available in the 1980s. General Motors Corporation introduced amass-production all-electric car in the mid-1990s. Automobiles that combine two or more types of engines are called hybrids. A typical hybrid is an electric motor with ba...
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Italy - country.
C Natural Resources Italy is poor in natural resources. Much of the land is unsuitable for agriculture because of mountainous terrain or unfavorable climate. Italy, moreover, lacks substantialdeposits of basic natural resources such as coal, iron, and petroleum. Natural gas is the country’s most important mineral resource. Other deposits include feldspar andpumice. Many of Italy’s mineral deposits on the islands of Sicily and Sardinia had been heavily depleted by the early 1990s. Italy is rich...
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Renault.
volume 8 Renault - la chaîne de montage de la Monaquatre dans l'île Seguin, page 4307, volume 8 Renault - la Nerva Stella, conduite intérieure de 7 places, page 4307, volume 8 Complétez votre recherche en consultant : Les corrélats Action directe automobile - La construction automobile Berliet Marius Boulogne-Billancourt Flins-sur-Seine Gordini Amédée nationalisation Renault Louis taylorisme Volvo Les livres automatisation - unité robotisée de tôlerie, page 463, volume 1 affi...
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Vatican City Facts and Figures.
Voting qualificationsLimited to cardinals under 80 years old ConstitutionApostolic Constitution of 1967, effective 1 March 1968 Armed forcesTotal number of military personnel Not available Military expenditures as a share of gross domestic product (GDP) Not available ECONOMYGross domestic product (GDP, in U.S.$) Not available GDP per capita (U.S.$) Not available GDP by economic sectorAgriculture, forestry, fishing Not available Industry Not available Services Not available Employ...
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San Marino Facts and Figures.
Male 96.8 percent (1995) Education expenditure as a share of gross national product (GNP) Not available Number of years of compulsory schooling 9 years (2002-2003) Number of students per teacher, primary school 5 students per teacher (1999-2000) GOVERNMENTForm of government Republic Voting qualifications Universal at age 18 Constitution8 October 1600; 1926 electoral law serves some of the functions of a constitution Armed forcesTotal number of military personnel Not available Military...
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Marshall Islands Facts and Figures.
Male 100 percent (1980) Education expenditure as a share of gross national product (GNP) 9.1 percent (2002-2003) Number of years of compulsory schooling 9 years (2000) Number of students per teacher, primary school 17 students per teacher (2001-2002) GOVERNMENTForm of governmentRepublic Voting qualifications Universal at age 18 Constitution 1 May 1979 Armed forcesTotal number of military personnel Not available Military expenditures as a share of gross domestic product (GDP) Not avail...
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Kiribati Facts and Figures.
Male Not available Education expenditure as a share of gross national product (GNP) 11.4 percent (1996) Number of years of compulsory schooling 10 years (2000) Number of students per teacher, primary school 22 students per teacher (2002-2003) GOVERNMENTForm of government Republic Voting qualifications Universal at age 18 Constitution 12 July 1979 Armed forcesTotal number of military personnel Not available Military expenditures as a share of gross domestic product (GDP) Not available...
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St. Kitts and Nevis Facts and Figures.
BASIC FACTS
Official name
Federation of
Female 97.5 percent (1995) Male 97.1 percent (1995) Education expenditure as a share of gross national product (GNP) 3.7 percent (2002-2003) Number of years of compulsory schooling 12 years (2002-2003) Number of students per teacher, primary school 17 students per teacher (2002-2003) GOVERNMENTForm of government Constitutional monarchy Voting qualifications Universal at age 18 Constitution 19 September 1983 Armed forcesTotal number of military personnel Not available Military expend...
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Dominica Facts and Figures.
Male 94 percent (1995) Education expenditure as a share of gross national product (GNP) 5.6 percent (1999-2000) Number of years of compulsory schooling 12 years (2002-2003) Number of students per teacher, primary school 19 students per teacher (2002-2003) GOVERNMENTForm of government Parliamentary democracy Voting qualifications Universal at age 18 Constitution 3 November 1978 Armed forcesTotal number of military personnel Not available Military expenditures as a share of gross domest...
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Samoa Facts and Figures.
Female 99.7 percent (2005 estimate) Male 99.7 percent (2005 estimate) Education expenditure as a share of gross national product (GNP) 4.5 percent (2001-2002) Number of years of compulsory schooling 10 years (2000) Number of students per teacher, primary school 27 students per teacher (2002-2003) GOVERNMENTForm of government Constitutional monarchy Voting qualifications Universal at age 21 Constitution 1 January 1962; amended 1997 Armed forcesTotal number of military personnel Not ava...
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Grenada Facts and Figures.
Female 97.6 percent (1995) Male 98 percent (1995) Education expenditure as a share of gross national product (GNP) 5.7 percent (2002-2003) Number of years of compulsory schooling 12 years (2002-2003) Number of students per teacher, primary school 19 students per teacher (2002-2003) GOVERNMENTForm of government Parliamentary democracy Voting qualifications Universal at age 18 Constitution 19 December 1973; suspended in 1979, restored in 1984 Armed forcesTotal number of military personn...
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Maldives Facts and Figures.
Education expenditure as a share of gross national product (GNP) 6.5 percent (1998-1999) Number of years of compulsory schooling 7 years (2002-2003) Number of students per teacher, primary school 20 students per teacher (2002-2003) GOVERNMENTForm of government Republic Voting qualifications Universal at age 21 Constitution 1 January 1998 Armed forcesTotal number of military personnel Not available Military expenditures as a share of gross domestic product (GDP) 6.4 percent (2003) ECON...
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Comoros Facts and Figures.
Literacy rateTotal 56.8 percent (2005 estimate) Female 49.7 percent (2005 estimate) Male 63.9 percent (2005 estimate) Education expenditure as a share of gross national product (GNP) 3.9 percent (2002-2003) Number of years of compulsory schooling 8 years (2002-2003) Number of students per teacher, primary school 37 students per teacher (2002-2003) GOVERNMENTForm of government Republic Voting qualifications Universal at age 18 Constitution New constitution came into force 23 December...
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Mauritania Facts and Figures.
Literacy rateTotal 42.6 percent (2005 estimate) Female 33 percent (2005 estimate) Male 52.5 percent (2005 estimate) Education expenditure as a share of gross national product (GNP) 3.6 percent (2002-2003) Number of years of compulsory schooling 9 years (2002-2003) Number of students per teacher, primary school 41 students per teacher (2002-2003) GOVERNMENTForm of government Republic Voting qualifications Universal at age 18 Constitution 12 July 1991 Armed forcesTotal number of milit...
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Mali Facts and Figures.
Literacy rateTotal 49.7 percent (2005 estimate) Female 43.1 percent (2005 estimate) Male 56.6 percent (2005 estimate) Education expenditure as a share of gross national product (GNP) 3 percent (1999-2000) Number of years of compulsory schooling 9 years (2002-2003) Number of students per teacher, primary school 57 students per teacher (2002-2003) GOVERNMENTForm of government Republic Voting qualifications Universal at age 21 Constitution Adopted 12 January 1992 Armed forcesTotal numb...
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Yemen Facts and Figures.
Female 33.2 percent (2005 estimate) Male 72.5 percent (2005 estimate) Education expenditure as a share of gross national product (GNP) 10.6 percent (2001-2002) Number of years of compulsory schooling 9 years (2002-2003) Number of students per teacher, primary school 30 students per teacher (1998-1999) GOVERNMENTForm of government Republic Voting qualifications Universal at age 18 Constitution 16 April 1991; amended 1994, 2000, 2001 Armed forcesTotal number of military personnel 66,700...
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Pierre Elliott Trudeau.
IV PRIME MINISTER After the resignation of Lester Pearson as leader of the Liberal Party, Trudeau was chosen as his successor, and on April 20, 1968, he became prime minister. He calleda general election and showed himself to be a brilliant campaigner, projecting an image of youthful charm and vitality. He argued for a united Canada with equal rightsfor French- and English-speaking citizens and opposed special status for any province. The voters gave him a substantial majority over Robert Stan...
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Pierre Elliott Trudeau - Canadian History.
IV PRIME MINISTER After the resignation of Lester Pearson as leader of the Liberal Party, Trudeau was chosen as his successor, and on April 20, 1968, he became prime minister. He calleda general election and showed himself to be a brilliant campaigner, projecting an image of youthful charm and vitality. He argued for a united Canada with equal rightsfor French- and English-speaking citizens and opposed special status for any province. The voters gave him a substantial majority over Robert Stan...
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baudelaire analyse
Baudelaire highlighting the time that passes through a progression from the past to the present, the discouraging record of this stormy youth is underlined by the past composed «on fait» (vers 3) and by the proposition of consequence to the present. The metaphor continues in the mention of a nature which has undergone the meteorological elements in their destructive character, the past having left traces: a life ravaged by «le tonnerre et la pluie», by the blows of fate and the daily grisai...
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Benin - country.
French is the official language of Benin, but most people speak an African language. Each of the country’s ethnic groups has its own language. Fon is the most widelyspoken language. About 52 percent of the population professes traditional religious beliefs, chiefly Vodun, a belief in spirits. Arab merchants introduced Islam to the region, and today it isthe religion of some 20 percent of the people, most of whom live in the north. Christianity, especially Roman Catholicism, is the religion of ab...
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Cognitive Psychology.
full richness of people’s cognitive experiences. Describing the act of remembering as a process of storage and retrieval, for example, neglects the subjective experienceof remembering. Another criticism is that information-processing theory may not reflect how the brain actually works. Newer models, such as the parallel distributedprocessing model, try to address this criticism by drawing on studies of brain structure and function. Psychologists continue to debate the adequacy of the information...
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Classification - biology.
species based on the fewest number of shared changes that have occurred from generation to generation. IV HISTORY OF CLASSIFICATION SYSTEMS Classification is one of the oldest sciences, but despite its age it is still a vigorous field full of new discoveries and methods. Much like other fields of science, greatthinkers have shaped the course of classification. One of the earliest classification schemes was established by Greek philosopher Aristotle, who lived in the 300s BC. Aristotle believe...
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Invertebrate - biology.
animals with a five-pointed design. They live in the sea and move with the help of tiny fluid-filled feet—another feature found nowhere else in the animal world. Zoologists recognize several different groups of worms. The phylum known as flatworms contains the simplest animals possessing heads. Nerves and sense organs areconcentrated in the head. Most flatworms are paper-thin and live in a variety of wet or damp habitats, including the digestive systems of other animals. Roundwormsrepresent anot...
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Invertebrate - biology.
animals with a five-pointed design. They live in the sea and move with the help of tiny fluid-filled feet—another feature found nowhere else in the animal world. Zoologists recognize several different groups of worms. The phylum known as flatworms contains the simplest animals possessing heads. Nerves and sense organs areconcentrated in the head. Most flatworms are paper-thin and live in a variety of wet or damp habitats, including the digestive systems of other animals. Roundwormsrepresent anot...
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Tree - biology.
The major parts of a tree are its roots, trunk, leaves, flowers, and seeds. These components play vital roles in a tree’s growth, development, and reproduction. A Roots Trees are held in place by anchoring organs called roots. In addition to anchoring the tree, roots also absorb water and minerals through tiny structures called roothairs. From the roots the water and mineral nutrients are carried upward through the wood cells to the leaves. Although the internal structure of most kinds of roots...
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Arctic - Geography.
The Arctic is not a frozen desert devoid of life on land or sea, even during the cold, dark winter months. Spring brings a phenomenal resurgence of plant and animal life.Low temperatures are not always the critical element—moisture, the type of soil, and available solar energy are also extremely important. Some animals adapt well toArctic conditions; for instance, a number of species of mammals and birds carry additional insulation, such as fat, in cold months. Arctic summers with extended dayli...
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Flower - biology.
insects. The sepals unfurl as the flower opens and often resemble small green leaves at the flower’s base. In some flowers, the sepals are colorful and work with thepetals to attract pollinators. E Variations in Structure Like virtually all forms in nature, flowers display many variations in their structure. Most flowers have all four whorls—pistil, stamens, petals, and sepals. Botanists callthese complete flowers. But some flowers are incomplete, meaning they lack one or more whorls. Incomplet...
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Astrobiology - astronomy.
water to help reactions along. American chemists Stanley Miller and Harold Urey tested part of Oparin and Haldane’s hypothesis in the early 1950s by simulating conditions of the early Earth. In whathas become known as the Miller-Urey experiment, the two scientists connected two flasks with a loop of glass tubing that allowed the gases to pass between the flasks.They filled the upper flask with methane, ammonia, and hydrogen—components thought to have been in the early atmosphere. They filled the...
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Perception (psychology).
A4 Closure According to the law of closure, we prefer complete forms to incomplete forms. Thus, in the drawing below, we mentally close the gaps and perceive a picture of a duck. This tendency allows us to perceive whole objects from incomplete and imperfect forms. A5 Common Fate The law of common fate leads us to group together objects that move in the same direction. In the following illustration, imagine that three of the balls are moving in one direction, and two of the balls are mo...
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Technology.
loose soil in this region, known as the Fertile Crescent, was easily scratched for planting, and an abundance of trees was available for firewood. By 5000 BC, farming communities were established in areas known today as Syria, Turkey, Lebanon, Israel, Jordan, Greece, and the islands of Crete and Cyprus. Agricultural societies in these places constructed stone buildings, used the sickle to harvest grain, developed a primitive plowstick, and advanced their skills inmetalworking. Trade in flint al...
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Whale - biology.
III BEHAVIOR OF WHALES Studies of whales in captivity have taught scientists much about the complex social behavior of whales. Since the late 1980s, advances in the use of satellite trackingsystems have also broadened opportunities for scientists to observe how whales behave in the wild. A Swimming and Diving Whales swim by making powerful up-and-down movements of the tail flukes, which provide thrust. The power comes from body muscles that flex the lower spine upand down in a wavelike motion...
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Alberta - Geography.
C Climate Except for the mountain areas, summers throughout the province are quite warm. Winters are long and extremely cold. In July, average daily temperatures range fromabout 16°C (about 60°F) along the northern boundary to about 21°C (about 70°F) in the south. In the extreme southeastern section of the province, temperatures of43°C (110°F) have been recorded. In January, average daily temperatures range from about -14°C (about 6°F) at Grande Prairie to about -9°C (about 16°F) atCalgary. Tem...
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Alberta - Canadian History.
C Climate Except for the mountain areas, summers throughout the province are quite warm. Winters are long and extremely cold. In July, average daily temperatures range fromabout 16°C (about 60°F) along the northern boundary to about 21°C (about 70°F) in the south. In the extreme southeastern section of the province, temperatures of43°C (110°F) have been recorded. In January, average daily temperatures range from about -14°C (about 6°F) at Grande Prairie to about -9°C (about 16°F) atCalgary. Tem...
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Turkey - country.
has a general elevation of 900 to 1,500 m (3,000 to 5,000 ft) above sea level. The eastern highlands region is the most mountainous and rugged portion of Turkey; Mount Ararat (Ağrı Da ğı) is the highest peak in the country at 5,165 m (16,945ft). Many Christians and Jews believe it to be the same Mount Ararat mentioned in the Bible as the place where Noah’s ark came to rest. The eastern highlands are thesource for both the Tigris (Dicle) and Euphrates (Fir āt)—two of southwestern Asia’s principal...
- Food Chain.
- Food Web - biology.
- Common Physics Equations.
- Nuclear Chemistry - chemistry.
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Mechanics
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INTRODUCTION
Mechanics, branch of physics concerning the motions of objects and their response to forces.
Components of VelocityNeglecting air resistance, a ball thrown into the air at an angle will travel in a parabolic path. The velocity of the ball (V)has independent vertical (V) and horizontal (H) components; the horizontal component stays the same the entire time theball is in the air, while the vertical component, the only component affected by gravity, changes continuously while theball is aloft.© Microsoft Corporation. All Rights Reserved. To understand why and how objects accelerate, force...
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Atom - chemistry.
Atoms have several properties that help distinguish one type of atom from another and determine how atoms change under certain conditions. A Atomic Number Each element has a unique number of protons in its atoms. This number is called the atomic number (abbreviated Z). Because atoms are normally electrically neutral,the atomic number also specifies how many electrons an atom will have. The number of electrons, in turn, determines many of the chemical and physical properties ofthe atom. The ligh...
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Atom
I
INTRODUCTION
Water Molecule
A water molecule consists of an oxygen atom and two hydrogen atoms, which are attached at an angle of 105°.
spontaneously break apart and change, or decay, into other atoms. Unlike electrons, which are fundamental particles, protons and neutrons are made up of other, smaller particles called quarks. Physicists know of six different quarks.Neutrons and protons are made up of up quarks and down quarks —two of the six different kinds of quarks. The fanciful names of quarks have nothing to do with their properties; the names are simply labels to distinguish one quark from another. Quarks are unique amo...
- Biochemistry - chemistry.
- Biochemistry - biology.
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Physics
I
INTRODUCTION
Physics, major science, dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces.
Starting about 1665, at the age of 23, Newton enunciated the principles of mechanics, formulated the law of universal gravitation, separated white light into colors,proposed a theory for the propagation of light, and invented differential and integral calculus. Newton's contributions covered an enormous range of naturalphenomena: He was thus able to show that not only Kepler's laws of planetary motion but also Galileo's discoveries of falling bodies follow a combination of his ownsecond law of m...
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Biodiversity.
a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...
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Biodiversity - biology.
a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...
- Enrico Fermi.
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Supernova - astronomy.
The term hypernova has been proposed for an extremely massive core-collapse supernova—possibly more than 100 times the mass of the Sun. A hypernova is thought to form a black hole. Just before it explodes, a hypernova may release a huge burst of gamma rays in a jet from the rotating black hole at its center. These jets mayexplain the so-called long gamma-ray bursts detected by astronomers. According to some researchers, massive stars with over 40 solar masses may sometimescollapse directly int...
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History of Astronomy - astronomy.
Egypt, the Sun was directly overhead at noon. On the same date and time in Alexandria, Egypt, the Sun was about 7 degrees south of zenith. With simple geometryand knowledge of the distance between the two cities, he estimated the circumference of the Earth to be 250,000 stadia. (The stadium was a unit of length, derivedfrom the length of the racetrack in an ancient Greek stadium. We have an approximate idea of how big an ancient Greek stadium was, and based on that approximationEratosthenes was...
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Molecule - chemistry.
attracted to the negatively charged electrons between them. The electrons belong to the molecule as a whole. However, each hydrogen atom now has a complete outershell of two electrons. The formula H 2 describes a hydrogen molecule, a discrete unit. When a molecule contains just two atoms, such as the hydrogen molecule does, it is called a diatomic molecule. Some atoms can form covalent bonds with more than one other atom and thus create a larger molecule. Atoms form molecules with covalent bo...