How do wheels and axles work?

Question

Please give me details!

Answer 1

http://howthingswork.virginia.edu/wheels.html

A wheel is a circular device capable of rotating on its axis, facilitating movement or transportation or performing labour in machines. A wheel together with an axle overcomes friction by facilitating motion by rolling. Common examples are found in transport applications. More generally the term is also used for other circular objects that rotate or turn, such as a Ship's wheel and flywheel.

The wheel (with axle) is considered one of the simple machines and lies near the starting point of advanced human technology (advanced, that is, in comparison with even earlier mechanical innovations such as stone/bone knives and axes, tension-sprung projectiles, scoops and shovels).

When wheels are used in conjunction with axles, either the wheel turns on the axle or the axle turns in a vehicle (as in a cart) or a housing (as in a mill). 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 reduce friction at the interface.

Example:

If dragging a 100 kg object for 10 m along a surface with 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. The normal force between the 4 wheels and axles is the same (in total) 981 N, assume μ = 0.1, and say the wheel diameter is 1000 mm and axle diameter is 50 mm. 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 0.1 x 0.5 = 49 joules.
Additional energy is lost at the wheel to road interface. This is termed rolling resistance which is predominantly a deformation loss.

good luck

Answer 2

The wheel was invented by the civilization of the Egyptians. It was derived from the log. A large team of Egyptian middle management met to determine the potential of the new device. There was a long and procastinating discussions over its fate. Some say wars were fought. However, following years of debate by the various advisory teams, white smoke rose over the senate of the day and it was decided that the wheel would be painted yellow. It was not until the Romans came along, realised its potential and said it could be any colour you like. Futher inovations took place, the original wheel was square and pythagoras calculated that if the wheel was triangular there would be one less bump and so from these humble beginnings the modern wheel has evolved. This will not enlighten you but the answer doesnt always have to!