Wheel: Wikis

  
  
  

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From Wikipedia, the free encyclopedia

Three wheels on an antique tricycle.
A wheel is a circular device that is capable of rotating on its axis, facilitating movement or transportation while supporting a load (mass), or performing labour in machines. Common examples are found in transport applications. A wheel, together with an axle overcomes friction by facilitating motion by rolling. In order for wheels to rotate, a moment needs to be applied to the wheel about its axis, either by way of gravity, or by application of another external force. .More generally the term is also used for other circular objects that rotate or turn, such as a ship's wheel, steering wheel and flywheel.^ Simple templates are used to enter course content, such as glossary terms, facts from lecture, or multiple choice questions.
  • Computing News from Send2Press Newswire :: Thu, 04 Feb 2010, 13:50:03 EST 6 February 2010 10:54 UTC www.send2press.com [Source type: General]

Contents

Etymology

The English word wheel comes from the Proto-Indo-European *kwekwlo-,[1] which was an extended form of the root *kwel- meaning "to revolve, move around". This is also the root of the Greek κυκλος kuklos, the Sanskrit chakra, and Persian charkh, all meaning "circle" or "wheel",[2] and also in Lithuanian, sukti means "to rotate". The Latin word rota is from the Proto-Indo-European *rotā-, the extended o-grade form of the root *ret- meaning "to roll, revolve".[3]

History

The use of wheels troughout history
A depiction of onager-drawn carts on the Sumerian "battle standard of Ur" (circa 2500 BC)
A spoked wheel on display at The National Museum of Iran, in Tehran. The wheel is dated late 2nd millennium BC and was excavated at Choqa Zanbil.
Most authorities regard the wheel as one of the oldest and most important inventions, which originated in ancient Mesopotamia in the 5th millennium BC (Ubaid period), originally in the function of potter's wheels. The earliest depiction of what may be a wheeled vehicle (here a wagon—four wheels, two axles), is on the Bronocice pot, a ca. 3500–3350 BC clay pot excavated in southern Poland.[4][5]
The wheel reached Europe and Western Asia in the 4th millennium BC, and the Indus Valley by the 3rd millennium BC. In China, the wheel is certainly present with the adoption of the chariot in ca. 1200 BC,[6] although Barbieri-Low (2000) argues for earlier Chinese wheeled vehicles, circa 2000 BC.
.Although they did not develop the wheel properly, the Olmec and certain other western hemisphere cultures seem to have approached it, as wheel-like worked stones have been found on objects identified as children's toys dating to about 1500 BC.[7] Early antiquity Nubians used wheels for spinning pottery and waterwheels.^ Two years ago, a similar study found 300 people, or 3%, said they had written software, but 70% of them did so for personal use.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

^ Children use PCs an average of 5.5 hours per week and usage peeks in the early teen years."
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

^ Other programmers say developers will not have much trouble once they get used to the changes.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

[8][9] .It is thought that Nubian waterwheels may have been ox-driven[10] It is also known that Nubians used horse-driven chariots imported from Egypt.^ They may not use those words, but this summer, pollsters will be randomly dialing 10,000 homes as part of an unusual survey commissioned by Microsoft Corp.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

[11]
The invention of the wheel thus falls in the late Neolithic, and may be seen in conjunction with the other technological advances that gave rise to the early Bronze Age. Note that this implies the passage of several wheel-less millennia even after the invention of agriculture. .Looking back even further, it is of some interest that although paleoanthropologists now date the emergence of anatomically modern humans to ca.150,000 years ago, 143,000 of those years were "wheel-less". That people with capacities fully equal to our own walked the earth for so long before conceiving of the wheel may be initially surprising, but populations were extremely small through most of this period and the wheel, which requires an axle and socket, and must be made round to actually be useful, is not as simple a device as it may seem.^ The people at Simple.com seem to think so.
  • memepool.com: Computing archive 6 February 2010 10:54 UTC memepool.com [Source type: General]

^ They may not use those words, but this summer, pollsters will be randomly dialing 10,000 homes as part of an unusual survey commissioned by Microsoft Corp.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

^ Until now, most of the Internet's growth has come from consumers plugging in through online services.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

Only with the domestication of the horse did the wheel show its true potential in Eurasia. Larger or heavier wheels benefit greatly from balancing , which requires a skilled wheelwright, a profession limited to organized societies.
Wide usage of the wheel was probably delayed because smooth roads were needed for wheels to be effective. Carrying goods on the back would have been the preferred method of transportation over surfaces that contained many obstacles. The lack of developed roads prevented wide adoption of the wheel for transportation until well into the 20th century in less developed areas.
Early wheels were simple wooden disks with a hole for the axle. Because of the structure of wood a horizontal slice of a trunk is not suitable, as it does not have the structural strength to support weight without collapsing; rounded pieces of longitudinal boards are required.
The spoked wheel was invented more recently, and allowed the construction of lighter and swifter vehicles. The earliest known examples are in the context of the Andronovo culture, dating to ca 2000 BC. Soon after this, horse cultures of the Caucasus region used horse-drawn spoked-wheel war chariots for the greater part of three centuries. They moved deep into the Greek peninsula where they joined with the existing Mediterranean peoples to give rise, eventually, to classical Greece after the breaking of Minoan dominance and consolidations led by pre-classical Sparta and Athens. Celtic chariots introduced an iron rim around the wheel in the 1st millennium BC. The spoked wheel had been in continued use without major modification until the 1870s, when wire wheels and pneumatic tires were invented.[12]
The invention of the wheel has also been important for technology in general, important applications including the water wheel, the cogwheel (see also antikythera mechanism), the spinning wheel, and the astrolabe or torquetum. More modern descendants of the wheel include the propeller, the jet engine, the flywheel (gyroscope) and the turbine.

Mechanics and function

The wheel is a device that enables efficient movement of an object across a surface where there is a force pressing the object to the surface. Common examples are a cart pulled by a horse, and the rollers on an aircraft flap mechanism.
Wheels are used in conjunction with axles, either the wheel turns on the axle, or the axle turns in the object body. The mechanics are the same in either case.
The low resistance to motion (compared to dragging) is explained as follows (refer to friction):
  • the normal force at the sliding interface is the same.
  • the sliding distance is reduced for a given distance of travel.
  • the coefficient of friction at the interface is usually lower.
Bearings are used to help reduce friction at the interface. In the simplest and oldest case the bearing is just a round hole through which the axle passes (a "plain bearing").
Example:
.
  • If dragging a 100 kg object for 10 m along a surface with the coefficient of friction μ = 0.5, the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5 × 10 = 4905 joules.
  • Now give the object 4 wheels.^ "Chipping at Intel" by Michael Meyer Nearly 150 million personal computers are working now, 9 out of 10 of them running Intel microprocessors.
    • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

    .The normal force between the 4 wheels and axles is the same (in total) 981 N, assume, for wood, μ = 0.25, and say the wheel diameter is 1000 mm and axle diameter is 50 mm.^ In 2000, online retail sales (dominated by computers, software, books, clothes) totaled $25.8 billion, says the Commerce Department.
    • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

    So while the object still moves 10 m the sliding frictional surfaces only slide over each other a distance of 0.5 m. The work done is 981 x 0.25 x 0.5 = 123 joules; the friction is reduced to 1/25 of that of dragging.
Additional energy is lost from the wheel-to-road interface. This is termed rolling resistance which is predominantly a deformation loss.
The wheel alone is not a machine, but when attached to an axle in conjunction with bearing, it forms the wheel and axle, one of the simple machines. A driven wheel is an example of a wheel and axle. Note that wheels pre-date driven wheels by about 6000 years.

Stability

Static stability of a wheeled vehicle
For unarticulated wheels, climbing obstacles will cause the body of the vehicle to rotate. If the rotation angle is too high, the vehicle will become statically unstable and tip over. .At high speeds, a vehicle can become dynamically unstable, able to be tipped over by an obstacle smaller than its static stability limit.^ "As of December, more than half of U.S. homes were wired with the high-speed pipeline to the Net.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

Without articulation, this can be an impossible position from which to recover.
For front-to-back stability, the maximum height of an obstacle which an unarticulated wheeled vehicle can climb is a function of the wheelbase and the horizontal and vertical position of the center of mass (CM).
The critical angle is the angle at which the center of mass of the vehicle begins to pass outside of the contact points of the wheels. Past the critical angle, the reaction forces at the wheels can no longer counteract the moment created by the vehicle's weight, and the vehicle will tip over. At the critical angle, the vehicle is marginally stable. The critical angle θcrit can be found by solving the equation:
	heta_{crit} = 	an^{-1} \left ( \frac {x_{cm} + r \sin 	heta_{crit}} {y_{cm} + r \sin 	heta_{crit}} \right )
where
r is the radius of the wheels;
xcm is the horizontal distance of the center of mass from the rear axle; and
ycm is the vertical distance of the center of mass from the axles.
For small wheels, this formula can be simplified to:
	heta_{crit} = 	an^{-1} \left ( \frac {x_{cm}} {y_{cm}} \right )
The maximum height h of an obstacle can be found by the equation:
\ h = w \sin 	heta_{crit}
where w is the wheelbase.
In the Unicode computer standard, the Dharmacakra is called the "Wheel of Dharma" and found in the eight-spoked form. It is represented as U+2638 (☸)

Alternatives

While wheels are used for ground transport very widely, there are alternatives, some of which are suitable for terrain where wheels are ineffective. Alternative methods for ground transport without wheels (wheel-less transport) include:

In symbology

The Romani flag
The flag of Mahl Kshatriyas
The wheel has also become a strong cultural and spiritual metaphor for a cycle or regular repetition (see chakra, reincarnation, Yin and Yang among others). As such and because of the difficult terrain, wheeled vehicles were forbidden in old Tibet.
The winged wheel is a symbol of progress, seen in many contexts including the coat of arms of Panama and the logo of the Ohio State Highway Patrol.
The introduction of spoked (chariot) wheels in the Middle Bronze Age appear to have carried somewhat of a prestige. The solar wheel appears to have a significance in Bronze Age religion, replacing the earlier concept of a Solar barge with the more "modern" and technologically advanced solar chariot.
The wheel is also the prominent figure on the flag of India. The wheel in this case represents law (dharma). It also appears in the flag of the Romani people, hinting to their nomadic history and their Indian origins. The wheel can also appears in the flag of Mahl Kshatiyas Kings (kattiri buvana maha radun).
In recent times, the custom aftermarket car/automobile roadwheel has become a status symbol. These wheels are often incorrectly referred to as "rims". The term "rim" is incorrect because the rim is only the outer portion of a wheel (where the tire is mounted), just as with a coffee cup or meteor crater. These "rims" have a great deal of variation, and are often highly polished and very shiny. Some custom "rims" include a bearing-mounted, free-spinning disc which continues to rotate by inertia after the automobile is stopped. In slang, these are referred to as "Spinners".

Gallery

See also

References

  1. ^ "wheel". Online Etymology Dictionary. http://www.etymonline.com/index.php?term=wheel. 
  2. ^ kwel-1. The American Heritage Dictionary of the English Language: Fourth Edition. 2000
  3. ^ ret- The American Heritage Dictionary of the English Language: Fourth Edition. 2000
  4. ^ Waza z Bronocic (in Polish)
  5. ^ Anthony, David A. (2007). The horse, the wheel, and language: how Bronze-Age riders from the Eurasian steppes shaped the modern world. Princeton, N.J: Princeton University Press. p. 67. ISBN 0-691-05887-3. 
  6. ^ Dyer, Gwynne, War: the new edition, p. 159: Vintage Canada Edition, Randomhouse of Canada, Toronto, ON
  7. ^ Ekholm, Gordon F (1945). "Wheeled Toys in Mexico". American Antiquity 11. 
  8. ^ CRAFTS; Uncovering Treasures of Ancient Nubia; New York Times
  9. ^ [http://wysinger.homestead.com/kush.html Ancient Sudan: (aka Kush & Nubia) City of Meroe (4th B.C. to 325 A.D.)]
  10. ^ What the Nubians Ate
  11. ^ The Cambridge History of Africa
  12. ^ bookrags.com – Wheel and axle

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

WHEEL (0. Eng. hweol, hweohl, &c., cognate with Icel. hjol, Dan. hiul, &'c.; the Indo-European root is seen in Sanskrit chakra, Gr. KUKXOS, circle, whence " cycle "), a circular frame or solid disk revolving on an axis, of which the function is to transmit or to modify motion. For the mechanical attributes and power of the wheel and for the modification of the lever, known as the " wheel and axis," and of the mechanical powers, see MECHANICS. The most familiar type of the wheel is of course that used in every type of vehicle, but it forms an essential part of nearly every kind of mechanism or machinery. .Vehicular wheels in the earliest times were circular disks either cut out of solid pieces of wood, or formed of separate planks of wood fastened together and then cut into a circular shape.^ And while we're collecting disks , we can branch out into saving other AOL memorabilia !
  • memepool.com: Computing archive 6 February 2010 10:54 UTC memepool.com [Source type: General]

.Such may be still seen in use among primitive peoples to-day, especially where the tracks, if any exist, are of the roughest description, and travelling is heavy.^ A few months ago I noticed people are still using Rexx to build dynamic web pages.
  • memepool.com: Computing archive 6 February 2010 10:54 UTC memepool.com [Source type: General]

The ordinary wheel consists of the nave (0. Eng. nafu, cf. Ger. Nabe, allied with navel "), the central portion or hub, through which the axle passes, the spokes, the radial bars inserted in the nave and reaching to the peripheral rim, the felloe or felly (0. Eng. felge, Ger. Felge, properly that which fitted together, Teut. felhan, to fit together). From the monuments we see that the ancient Egyptian and Assyrian chariots had usually six spokes; the Greek and Roman wheels from four to eight. (See further CARRIAGE and CHARIOT; also TIRE; and articles on BICYCLE; TRICYCLE; and MOTOR VEHICLES.)


Wiktionary

Up to date as of January 15, 2010
(Redirected to wheel article)

Definition from Wiktionary, a free dictionary

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Contents

English

Etymology

Old English hwēoġol, hwēol, from Proto-Germanic *khwekhwlan, *khwegwlan, from Proto-Indo-European *kwe-k(w)lo-, wheel, circle, a reduplicated form of Proto-Indo-European base *k(w)el-, to go round. Cognate with Dutch wiel, wheel; Old Church Slavonic коло; Latin colere (to cultivate, to inhabit; = to turn around); and Old Norse hvél, hjól, wheel

Pronunciation

Noun

Singular
wheel
Plural
wheels
wheel (plural wheels)
  1. A circular device capable of rotating on its axis, facilitating movement or transportation or performing labour in machines.
  2. (informal, with "the") A steering wheel and its implied control of a vehicle.
  3. (nautical) The instrument attached to the rudder by which a vessel is steered.
  4. (slang) A person with a great deal of power or influence; a big wheel.
  5. (poker slang) The lowest straight in poker: ace, 2, 3, 4, 5.
  6. (automotive) wheel rim

Synonyms

  • (wheel rim): rim

Derived terms

See also

Translations

References

Verb

Infinitive
to wheel
Third person singular
wheels
Simple past
wheeled
Past participle
wheeled
Present participle
wheeling
to wheel (third-person singular simple present wheels, present participle wheeling, simple past and past participle wheeled)
  1. (intransitive or transitive) To roll along as on wheels.
    Wheel that trolley over here, would you?
  2. (intransitive) To travel around in large circles, particularly in the air.
    The vulture wheeled above us.

Derived terms

Translations


Bible wiki

Up to date as of January 23, 2010

From BibleWiki

(Heb. galgal; rendered "wheel" in Ps 8313, and "a rolling thing" in Isa 17:13; R.V. in both, "whirling dust"). .This word has been supposed to mean the wild artichoke, which assumes the form of a globe, and in autumn breaks away from its roots, and is rolled about by the wind in some places in great numbers.^ Jennifer Tanaka, "Number Game", Newsweek, July 31, 1995 "Some of the Internet's top demographers have banded together to form a clearinghouse for Net stats.
  • Computer Almanac - Numbers About Computers 10 February 2010 13:40 UTC www.cs.cmu.edu [Source type: FILTERED WITH BAYES]

This entry includes text from Easton's Bible Dictionary, 1897.
what mentions this? (please help by turning references to this page into wiki links)

In the Bible wheels are mentioned in connection with ordinary wagons, as well as with Chariots. Mention is made also of the thrashing-wheel (Prov 20:26; Isa 28:27), and of the potters' wheel or disk (Jer 18:3; see Pottery).
This entry includes text from the Jewish Encyclopedia, 1906.

Simple English

File:Wagenraeder-FH000008
Some very old wooden wheels.

A wheel is a disc- or circle-shaped mechanical device. Its main purpose is to allow things to roll; in other words, the wheel spins, and objects on the wheels move more easily along the ground. It is a simple machine.

History

Most experts believe the ancient Mesopotamians invented the wheel about 8000 BC. In addition, the ASIA discovered it on their own around 3500 BC. The Inca and Maya had wheels on children's toys around 1500 BC, but they did not use wheels for work. Africa south of the Sahara desert and Australia did not have the wheel until people there met people from other cultures.


Citable sentences

Up to date as of December 14, 2010

Here are sentences from other pages on Technology, which are similar to those in the above article.








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