What Is Wheel

---

A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six simple machines. Wheels, in conjunction with axles, allow heavy objects to be moved easily facilitating movement or transportation while supporting a load, or performing labor in machines. Wheels are also used for other purposes, such as a ship's wheel, steering wheel, potter's wheel, and flywheel.

Common examples can be found in transport applications. A wheel reduces friction by facilitating motion by rolling together with the use of axles. 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 the application of another external force or torque. Using the wheel, Sumerians invented a device that spins clay as a potter shapes it into the desired object.





Terminology
The English word wheel comes from the Old English word hwēol, from Proto-Germanic *hwehwlaz, from Proto-Indo-European *kwékwlos,[1] an extended form of the root *kwel- "to revolve, move around". Cognates within Indo-European include Icelandic hjól "wheel, tyre", Greek κύκλος kúklos, and Sanskrit chakra, the last two both meaning "circle" or "wheel".[2]

History
The place and time of the invention of the wheel remains unclear, because the oldest hints do not guarantee the existence of real wheeled transport, or are dated with too much scatter.[3] Mesopotamian civilization is credited with the invention of the wheel by old sources.[4][5][6] However, more recent sources suggest that the wheel was invented in Eastern Europe first or that it was invented independently in both Mesopotamia and Eastern Europe[7][8][9][10] and that unlike other breakthrough inventions, the wheel cannot be attributed to a single nor several inventors. Evidence of early usage of wheeled carts has been found across the Middle East, in Europe, Eastern Europe, India and China. It is not known whether Chinese, Indians, Europeans and even Sumerians invented the wheel independently or not.[11][12]

The invention of the solid wooden disk wheel falls into the late Neolithic, and may be seen in conjunction with other technological advances that gave rise to the early Bronze Age. This implies the passage of several wheelless millennia even after the invention of agriculture and of pottery, during the Aceramic Neolithic.

4500–3300 BCE (Copper Age): invention of the potter's wheel; earliest solid wooden wheels (disks with a hole for the axle); earliest wheeled vehicles; domestication of the horse
3300–2200 BCE (Early Bronze Age)
2200–1550 BCE (Middle Bronze Age): invention of the spoked wheel and the chariot

This Ljubljana Marshes Wheel with axle is the oldest wooden wheel yet discovered dating to Copper Age (c. 3,130 BCE)
The Halaf culture of 6500–5100 BCE is sometimes credited with the earliest depiction of a wheeled vehicle, but this is doubtful as there is no evidence of Halafians using either wheeled vehicles or even pottery wheels.[13] Precursors of pottery wheels, known as "tournettes" or "slow wheels", were known in the Middle East by the 5th millennium BCE. One of the earliest examples was discovered at Tepe Pardis, Iran, and dated to 5200–4700 BCE. These were made of stone or clay and secured to the ground with a peg in the center, but required significant effort to turn. True potter's wheels, which are freely-spinning and have a wheel and axle mechanism, were developed in Mesopotamia (Iraq) by 4200–4000 BCE.[14] The oldest surviving example, which was found in Ur (modern day Iraq), dates to approximately 3100 BCE.[15] Wheels of uncertain dates have also been found in the Indus Valley civilization, a 4th millennium BCE civilization covering areas of present-day India and Pakistan.

---