Pulley:
A pulley is a wheel with a groove for a rope. When something is attached to the rope, it can be moved by pulling on the other end that has looped around the pulley.
Screw:
A screw is an inclined plane that is wrapped around a cylinder. Examples of screws include: fasteners that are used to attach wood or metal; lifting screws that are used to lift heavy objects and dig holes; and bolts that are used with nuts to keep things together.
Wedge:
The wedge is two inclined planes put together. It can be used to split things apart, such as an ax, or to hold things, such as a doorstop.
Lever:
A lever consists of a bar that rotates around a pivot point called the fulcrum. Levers make work easier by applying force over a longer distance. This means the same work is done with less applied force. Example: seesaw, and human arm.
Wheel and axle:
A wheel-and-axle is a wheel attached to a rod or stick. It works similarly to a lever, in that, considering movement about the circumference, the distance the wheel-circle moves is much greater then the distance the smaller axle-circle moves.
Inclined plane:
An inclined plane is a ramp that reduces the force needed to move an object. Consequently, the object must travel a longer distance. Example: inclined planes were used by the Egyptians to build the pyramids.
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