Invention of Wheel Has Changed Our Lives

Invention of wheel has changed our lives
A wheel is a circular object that, together with an axle, rolls easily. They were first widely used for transport. Wheel can mean lots of other circular objects that turn, like a steering wheel and flywheel.
The wheel was invented in prehistoric times and probably its discovery was repeated many times independently. The oldest example of a wheel yet found is from the region of Mesopotamia (Iraq), so it may have been invented around the area where Iraq is today. The wheel may have been inspired by a simple observation of a rolling tree trunk. When a number of tree trunks are placed on the ground close together, and a weight is placed upon them, the object can be moved much more easily. The rolling trunks cause less friction than dragging the object on the ground.
The first wheels were indeed tree trunks. The next development was to use slices of these trunks joined together through an axle. Later, these wheels became wooden disks cut into a circular shape with a hole for the axle. The oldest wooden wheel archaeologists have found was built somewhere between 3350 and 3100 BC. Because the first wheels were made from wood, and wood rots and breaks down over time, we can assume that other wheels might have existed earlier.
Wheels with spokes were invented more recently. This type of wheel allowed people to make lighter and faster vehicles. The earliest known examples were from chariots built about 2000 BC.
A wheel works by rolling. Rolling is a powerful way to reduce friction. When you slide a block across a smooth surface, it will slide for a short distance and then come to a stop. When you roll a ball across that surface, it will roll a long way. Rolling friction is much weaker than sliding friction.
There are two basic parts of wheels; the wheel and the axle. The wheel itself is a round disk. The axle is a shaft positioned in the center of the disk. Sometimes the disk itself spins on the axle. Often the axle is fixed to...