Wikijunior:How Things Work/Screw
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Screws are one of the six simple machines.
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[edit] Who invented it?
The Greek mathematician Archytas of Tarentum is credited with the invention of the screw. By the 1st century BC, wooden screws were commonly used throughout the Mediterranean world in devices such as oil and wine presses. Metal screws used as fasteners did not appear in Europe until the 1400s.
[edit] How does it get power?
A screw is powered by the movement of the screw driver.
[edit] How does it work?
A screw used as a threaded fastener consists of a shaft, which may be cylindrical or conical, and a head. The shaft has a ridge or thread running around it in a spiral or "helix" shape. The thread mates with a complementary helix in the material. The head is specially shaped to allow a screwdriver or wrench to grip the screw when driving it in.
There are also "Water Screws" or the augur. This is a technique for lifting or pumping water using a screw style pump. As the screw turn in the water, the water is lifted. This is also how a concrete mixer (truck) unloads it load of concrete.
[edit] How dangerous is it?
Screws are not usually dangerous, but some screws have a point that could scratch or puncture you.
[edit] What does it do?
Usually, screws are used to hold materials together. Sometimes screws are used to move fluids or small objects. Screws used as fasteners can be removed and reinserted many times without reducing their effectiveness. They have greater holding power than nails and permit disassembly and reuse.
[edit] How does it vary?
Certain screws may have different shapes, sizes, etc. to suit different needs.
[edit] How has it changed the world?
[edit] What idea(s) and/or inventions had to be developed before it could be created?
The screw is like a ramp wrapped around a pole, and the ramp had to be invented first.
