Tyre dating marks Unregistered cam chat


08-Aug-2017 10:48

Nubians from after about 400 BCE used wheels for spinning pottery and as water wheels.Early wheels were simple wooden disks with a hole for the axle.Common examples are found in transport applications.A wheel greatly reduces friction by facilitating motion by rolling together with the use of axles.Celtic chariots introduced an iron rim around the wheel in the 1st millennium BCE.The spoked wheel was in continued use without major modification until the 1870s, when wire-spoked wheels and pneumatic tires were invented.

This energy is also lowered by the use of a wheel (in comparison to dragging) because the net force on the contact point between the road and the wheel is almost perpendicular to the ground, and hence, generates an almost zero net work.

The wire spokes are under tension, not compression, making it possible for the wheel to be both stiff and light.

Early radially-spoked wire wheels gave rise to tangentially-spoked wire wheels, which were widely used on cars into the late 20th century.

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.

Precursors of 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).The closest relative of cattle present in Americas in pre-Columbian times, the American Bison, is difficult to domesticate and was never domesticated by Native Americans; several horse species existed until about 12,000 years ago, but ultimately became extinct.