Vocabulary• A wheel is a lever that can turn 360

degrees and can have an effort or resistance applied anywhere on that surface. The effort or resistance force can be applied either to the outer wheel or the inner wheel (axle).

• An axle is the spindle on which one or more wheels revolve.

• Resistance is the force we are trying to overcome.

• Effort is the forces we use to overcome resistance.

• The fulcrum is the point or support about which a lever turns.

A wheel and axle is a lever that rotates in a circle around a center point or fulcrum. The larger wheel (or outside) rotates around the smaller wheel (axle). All wheels need an axle. The wheel and axle must move together to be a simple machine. wheel

A wheel and axle lifts or moves loads. Bicycle wheels, Ferris wheels and gears are all examples of a wheel and axle. Wheels can also have a solid shaft with the center core as the axle. Examples of these are screwdrivers, drill bits or the log in a log rolling contest.

If effort is applied to the wheel, it turns the axle. They both move together. The larger the wheel the greater the force over the distance of the axle. This is evident in steering wheels and doorknobs.

                     

Resistance Effort

Fulcrum

If effort is applied to the axle, the wheel turns. Examples include vehicle wheels, motorized fans and circular saws.

Effort

Fulcrum

Resistance

Two Machines in One?

A wheel and axle is really two machines in one because you can use each part in different ways.

Two Machines in One? The first way is to roll something along.

Wheels help you move an object across the ground because they cut down on the amount of friction between what you're trying to move and the surface you're pulling it against. (The axle is the object that attaches the wheel to the object it's moving.) Since only the very bottom of the wheel touches the ground, there is less surface area to rub — and less friction. Imagine pulling a little red wagon without any wheels! Generally speaking, the bigger the wheel, the easier it is to make something roll.

Two Machines in One? The second way of using a wheel is like a

round lever. A door knob or a faucet on a sink are really round levers, and the "fulcrum" is in the middle where the axle turns. Imagine if a door knob was replaced with a little rod. It would be much harder to open the door! Once again, there's a trade-off: The larger the diameter of the wheel, the less effort you need to turn it, but you have to move the wheel a greater distance to get the same work done.

• Completion Date: 2008• Height: 169 meters (555ft)

(equivalent to 42 story building)

• Diameter: 150 meters (492 ft)• Duration of ride:

37 minutes. The ride will be operational 16 hours a day.

• Capsules:Comprises 28 fully air-conditioned and UV protected capsules that can comfortably carry 32 people each (max 36).

Did You Know?

• The wheel and axle is a type of lever. If the wheel is turning the axle, it’s a type of second-class lever. The radius of the axle is a resistance arm. The center of the axle is the fulcrum.

ReferencesInformation used from and credited to the following websites:

• http://www.sirinet.net/~jgjohnso/simple.html• http://forum.skyscraperpage.com/showthread.php?t=102884• http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines/sciber/machine7.htm• http://sln.fi.edu/pieces/knox/automaton/wheel.htm• http://teacher.scholastic.com/dirtrep/simple/wheel.htm• http://www.msichicago.org/ed/scienceminute/ScienceMinute4.06.pdf• http://www.lessonplanspage.com/ScienceSimpleMachines-WheelAxle46.htm