hammer |
carrot |
top 10 words in brain distribution (in article): design head animal size common allow form time hand shape |
top 10 words in brain distribution (in article): plant produce fruit drink grow species seed sugar leaf variety |
top 10 words in brain distribution (not in article): key lock switch machine needle type tube bicycle knit wire |
top 10 words in brain distribution (not in article): light water lamp animal wine tree beer time contain bottle |
times more probable under hammer 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under carrot (words not in the model) | |
A hammer'" is a tool meant to deliver an impact to an object. The most common uses are for driving nails, fitting parts, and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure. Usual features are a handle and a head, with most of the weight in the head. The basic design is hand-operated, but there are also many mechanically operated models for heavier uses. The hammer is a basic tool of many professions, and can also be used as a weapon. By analogy, the name "'hammer'" has also been used for devices that are designed to deliver blows, e.g. in the caplock mechanism of firearms. History. The use of simple tools dates to about 2,400,000 BCE when various shaped stones were used to strike wood, bone, or other stones to break them apart and shape them. Stones attached to sticks with strips of leather or animal sinew were being used as hammers by about 30,000 BCE during the middle of the Paleolithic Stone Age. Its archeological record means it is perhaps the oldest human tool known. Designs and variations. The essential part of a hammer is the head, a compact solid mass that is able to deliver the blow to the intended target without itself deforming. The opposite side of a ball as in the ball-peen hammer and the cow hammer. Some upholstery hammers have a magnetized appendage, to pick up tacks. In the hatchet the hammer head is secondary to the cutting edge of the tool. In recent years the handles have been made of durable plastic or rubber. The hammer varies at the top, some are larger than others giving a larger surface area to hit different sized nails and such, Mechanically-powered hammers often look quite different from the hand tools, but nevertheless most of them work on the same principle. They include: In professional framing carpentry, the hammer has almost been completely replaced by the nail gun. In professional upholstery, its chief competitor is the staple gun. Hammer as a force amplifier. A hammer is basically a force amplifier that works by converting mechanical work into kinetic energy and back. In the swing that precedes each blow, a certain amount of kinetic energy gets stored in the hammer's head, equal to the length "D" of the swing times the force "f" produced by the muscles of the arm and by gravity. When the hammer strikes, the head gets stopped by an opposite force coming from the target; which is equal and opposite to the force applied by the head to the target. If the target is a hard and heavy object, or if it is resting on some sort of anvil, the head can travel only a very short distance "d" before stopping. Since the stopping force "F" times that distance must be equal to the head's kinetic energy, it follows that "F" will be much greater than the original driving force "f" — roughly, by a factor "D" "d". In this way, great strength is not needed to produce a force strong enough to bend steel, or crack the hardest stone. Effect of the head's mass. The amount of energy delivered to the target by the hammer-blow is equivalent to one half the mass of the head times the square of the head's speed at the time of impact ([Formula 1]). While the energy delivered to the target increases linearly with mass, it increases geometrically with the speed (see the effect of the handle, below). High tech titanium heads are lighter and allow for longer handles, thus increasing velocity and delivering more energy with less arm fatigue than that of a steel head hammer of the same weight. As hammers must be used in many circumstances, where the position of the person using them cannot be taken for granted, trade-offs are made for the sake of practicality. In areas where one has plenty of room, a long handle with a heavy head (like a sledge hammer) can deliver the maximum amount of energy to the target. But clearly, it's unreasonable to use a sledge hammer to drive upholstery tacks. Thus, the overall design has been modified repeatedly to achieve the optimum utility in a wide variety of situations. Effect of the handle. The handle of the hammer helps in several ways. It keeps the user's hands away from the point of impact. It provides a broad area that is better-suited for gripping by the hand. Most importantly, it allows the user to maximize the speed of the head on each blow. The primary constraint on additional handle length is the lack of space in which to swing the hammer. This is why sledge hammers, largely used in open spaces, can have handles that are much longer than a standard carpenter's hammer. The second most important constraint is more subtle. Even without considering the effects of fatigue, the longer the handle, the harder it is to guide the head of the hammer to its target at full speed. Most designs are a compromise between practicality and energy efficiency. Too long a handle: the hammer is inefficient because it delivers force to the wrong place, off-target. Too short a handle: the hammer is inefficient because it doesn't deliver enough force, requiring more blows to complete a given task. Recently, modifications have also been made with respect to the effect of the hammer on the user. A titanium head has about 3% recoil and can result in greater efficiency and less fatigue when compared to a steel head with about 27% recoil. Handles made of shock-absorbing materials or varying angles attempt to make it easier for the user to continue to wield this age-old device, even as nail guns and other powered drivers encroach on its traditional field of use. War hammers. The concept of putting a handle on a weight to make it more convenient to use may well have led to the very first weapons ever invented. The club is basically a variant of a hammer. In the Middle Ages, the war hammer became popular when edged weapons could no longer easily penetrate some forms of armour. Symbolic hammers. The hammer, being one of the most used tools by "Homo sapiens", has been used very much in symbols and arms. In the Middle Ages it was used often in blacksmith guild logos, as well as in many family symbols. The most recognised symbol with a hammer in it is the Hammer and Sickle, which was the symbol of the former Soviet Union. The hammer in this symbol represents the industrial working class (and the sickle the agricultural working class). The hammer is used in some coat of arms in (former) socialist countries like East Germany. In Norse Mythology, Thor, the god of thunder and lightning, wields a hammer named Mjolnir. Many artifacts of decorative hammers have been found leading many modern practitioners of this religion to often wear reproductions as a sign of their faith. | The carrot'" ("Daucus carota" subsp. "sativus", Etymology: Middle French "carotte", from Late Latin "carōta", from Greek "karōton", originally from the Indoeuropean root "ker-" (horn), due to its horn-like shape) is a root vegetable, usually orange or white, or red-white blend in colour, with a crisp texture when fresh. The edible part of a carrot is a taproot. It is a domesticated form of the wild carrot "Daucus carota", native to Europe and southwestern Asia. It has been bred for its greatly enlarged and more palatable, less woody-textured edible taproot, but is still the same species. It is a biennial plant which grows a rosette of leaves in the spring and summer, while building up the stout taproot, which stores large amounts of sugars for the plant to flower in the second year. The flowering stem grows to about 1 metre (3 ft) tall, with an umbel of white flowers that produce a fruit called a mericarp by botanists, which is a type of schizocarp. Uses and nutrition. Carrots can be eaten in a variety of ways. The simplest way is raw as carrots are perfectly digestible without requiring cooking. Alternatively they may be chopped and boiled, fried or steamed, and cooked in soups and stews, as well as baby and pet foods. A well known dish is "carrots julienne". Grated carrots are used in carrot cakes, as well as carrot puddings, an old English dish thought to have originated in the early 1800s. The greens are edible as a leaf vegetable, but are rarely eaten by humans, as they are mildly toxic. Together with onion and celery, carrots are one of the primary vegetables used in a "mirepoix" to make various broths. Ever since the late 1980s, baby carrots or mini-carrots (carrots that have been peeled and cut into uniform cylinders) have been a popular ready-to-eat snack food available in many supermarkets. Carrot juice is also widely marketed, especially as a health drink, either stand-alone or blended with fruits and other vegetables. The carrot gets its characteristic and bright orange colour from β-carotene, which is metabolised into vitamin A in humans when bile salts are present in the intestines. Massive overconsumption of carrots can cause hypercarotenemia, a condition in which the skin turns orange (although hypercarotenemia is not itself dangerous unlike overdose of vitamin A, which can cause liver damage). Carrots are also rich in dietary fibre, antioxidants, and minerals. Lack of Vitamin A can cause poor vision, including night vision, and vision can be restored by adding Vitamin A back into the diet. The urban legend that says eating large amounts of carrots will allow one to see in the dark developed from stories of British gunners in World War II who were able to shoot down German planes in the darkness of night. The legend arose during the Battle of Britain when the RAF circulated a story about their pilots' carrot consumption as an attempt to cover up the discovery and effective use of radar technologies in engaging enemy planes. It reinforced existing German folklore and helped to encourage Britons—looking to improve their night vision during the blackouts—to grow and eat the vegetable. Ethnomedically, the roots are used to treat digestive problems, intestinal parasites, and tonsillitis or constipation. History. The wild ancestors of the carrot are likely to have come from Afghanistan, which remains the centre of diversity of "D. carota", the wild carrot. Selective breeding over the centuries of a naturally-occurring subspecies of the wild carrot, "Daucus carota" subsp. "sativus" reducing bitterness, increasing sweetness and minimizing the woody core, has produced the familiar garden vegetable. In early use, carrots were grown for their aromatic leaves and seeds, not their roots. Some relatives of the carrot are still grown for these, such as parsley, fennel, dill and cumin. The first mention of the root in classical sources is in the 1st century CE. The modern carrot appears to have been introduced to Europe in the 8-10th centuries; Ibn al-Awam, in Andalusia, describes both red and yellow carrots; Simeon Seth also mentions both colours in the 11th century. Orange-coloured carrots appeared in the Netherlands in the 17th century. These, the modern carrots, were intended by the antiquary John Aubrey (1626-1697) when he noted in his memoranda "Carrots were first sown at Beckington in Somersetshire Some very old Man there [in 1668] did remember their first bringing hither." In addition to wild carrot, these alternative (mostly historical) names are recorded for "Daucus carota": Bee's-nest, Bee's-nest plant, Bird's-nest, Bird's-nest plant, Bird's-nest root, Carota, Carotte (French), Carrot, Common carrot, Crow's-nest, Daucon, Dawke, Devil's-plague, Fiddle, Gallicam, Garden carrot, Gelbe Rübe (German), Gingidium, Hill-trot, Laceflower, Mirrot, Möhre (German), Parsnip (misapplied), Queen Anne's lace, Rantipole, Staphylinos, and Zanahoria. The parsnip is a close relative of the carrot, as is parsley. Cultivars. Carrot cultivars can be grouped into two broad classes, eastern carrots'" and "'western carrots'". More recently, a number of novelty cultivars have been bred for particular characteristics. The world's largest carrot was grown in Palmer, Alaska by John Evans in 1998, weighing 8.6 kg (19 lb). The city of Holtville, California promotes itself as "Carrot Capital of the World", and holds an annual festival devoted entirely to the carrot. Eastern carrots. Eastern carrots were domesticated in Central Asia, probably in modern-day Afghanistan in the 10th century, or possibly earlier. Specimens of the eastern carrot that survive to the present day are commonly purple or yellow, and often have branched roots. The purple colour common in these carrots comes from anthocyanin pigments. Western carrots. The western carrot emerged in the Netherlands in the 17th century, its orange colour making it popular in those countries as an emblem of the House of Orange and the struggle for Dutch independence. The orange colour results from abundant carotenes in these cultivars. While orange carrots are the norm in the West, other colours do exist, including white, yellow, red, and purple. These other colours of carrot are raised primarily as novelty crops. The Vegetable Improvement Center at Texas A&M University has developed a purple-skinned, orange-fleshed carrot, the "BetaSweet" (also known as the Maroon Carrot), with substances to prevent cancer, which has recently entered very limited commercial distribution, through J&D Produce of Edinburg TX. This variety of carrot is also known to be high in β-carotene which is an essential nutrient. The high concentrations of this nutrient give the carrot its maroon shade. Western carrot cultivars are commonly classified by their root shape: While any carrot can be harvested before reaching its full size as a more tender "baby" carrot, some fast-maturing cultivars have been bred to produce smaller roots. The most extreme examples produce round roots about 2.5 centimetres (1 in) in diameter. These small cultivars are also more tolerant of heavy or stony soil than long-rooted cultivars such as 'Nantes' or 'Imperator'. The "baby carrots" sold ready-to-eat in supermarkets are, however, often not from a smaller cultivar of carrot, but are simply full-sized carrots that have been sliced and peeled to make carrot sticks of a uniform shape and size. Carrot flowers are pollinated primarily by bees. Seed growers use honeybees or mason bees for their pollination needs. Carrots are used as food plants by the larvae of some Lepidoptera species, including Common Swift, Garden Dart, Ghost Moth, Large Yellow Underwing and Setaceous Hebrew Character. Novelty carrots. Food enthusiasts and researchers have developed other varieties of carrots through traditional breeding methods. Novelty carrots are also grown throughout Western Europe in flower pots and are noted for their distinctly minty flavour. One particular variety lacks the usual orange pigment from carotenes, owing its white colour to a recessive gene for tocopherol (Vitamin E). Derived from "Daucus carota" L. and patented (US patent #6,437,222) at the University of Wisconsin-Madison, the variety is intended to supplement the dietary intake of Vitamin E. Production trends. In 2005, China was the largest producer of carrots and turnips, according to the FAO. China accounted for at least one third of the global output, followed by Russia and the United States. In 2005, a poll of 2,000 people revealed that the carrot was Britain's third favourite culinary vegetable. |