Lever

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Diagram of the use of a first-class lever (blue) on a fulcrum (brown)

A lever is a simple machine. It is something that can be used in a lot of ways. One way is by measuring things, or by seeing which weighs more. A lever is supported by a fulcrum which it uses to lifts weights. It is one of six simple machines. There are three types of levers: first-class, second-class and third-class.

Early[change | change source]

The earliest remaining writings about levers are from the 3rd century BC. They were writtentand, and I shall move the earth." is a famous quote of Archimedes who stated the correct mathematical principle of levers (quoted by Pappus of Alexandria).[1]

Types of levers[change | change source]

There are three kinds of levers. The difference between them is where the fulcrum is and where the forces are.

First class[change | change source]

A first-class lever

A first-class lever is a lever where the fulcrum is in between the effort and resistance (the load). Seesaws and crowbars are examples of first class levers.

Second class[change | change source]

A second-class lever is where the resistance is between the effort and the fulcrum. Wheel barrows and wrenches are examples of second class levers.

Third class[change | change source]

A third class lever is where the effort is between the resistance and the fulcrum. Staplers and your forearm are examples of third class levers.

References[change | change source]

  1. Mackay, Alan Lindsay (1991). "Archimedes ca 287–212 BC". A Dictionary of scientific quotations. London: Taylor and Francis. p. 11. ISBN 9780750301060 .