Archimedes’ Screw

Archimedes' screw is an inclined plane wrapped around a wedge placed inside a tube. It has been used since ancient times to lift water. The device, often used to direct water into an irrigation channel, was composed of a wooden beam, several feet long, around which a spiral screw thread was built of layers of flexible, pitch-covered wood strips.

Over this thread were fastened tight-fitting narrow planks running the length of the beam and giving it the appearance of a tube.

To operate the screw, it is angled into the water so that some part of the inclined plane is in the water. When the handle of the screw is turned the right way, the water is lifted up until it flows out of the tube's upper end.

Six simple devices

Levers

Levers are simple devices that make our work easier. There are at least three parts in a lever. They are the fulcrum, the resistance, and the force. There are three kinds of levers.

First Class Lever

In a first class lever, the fulcrum is in the middle; the resistance is at one end and the force is at the other end. Examples of the first class lever are scissors, crowbars, and seesaws.

Second Class Lever

A second class lever has the force on one end, the fulcrum on the other and the resistance in the middle. Examples of this lever are nutcrackers, oars of a boat, and wheelbarrows.

Third Class Lever

In the third class lever, the resistance is at one end, the force is at the middle, and the fulcrum is at the other end. Tweezers, baseball bats, and your arm are all examples of third class levers.

Pulleys

Pulleys are made of a spool and a rope. They are used to move elevators, raise flags, and many other things.

Wheel and Axle

A wheel and axle helps make lifting things easier. It works by turning the wheel.

Inclined Plane

It helps to make lifting things easier.

Wedge

A wedge helps keep things in place.

Screw

A screw is an inclined plane wrapped around a wedge. See Archimedes’ Screw.