Lever resistance (or load). It is common to call the input force "the effort" and the output force "the load" or "the resistance." This allows the identification of three classes of levers by the relative locations of the fulcrum, the resistance and the effort: These cases are described by the mnemonic "fre 123" where the fulcrum is in the middle for the 1st class lever, the "r"esistance is in the middle for the 2nd class lever, and the effort is in the middle for the 3rd class lever. The lever is a movable bar that pivots on a fulcrum attached to
Lever of the lever. The word "lever" entered English about 1300 from Old French, in which the word was "levier". This sprang from the stem of the verb "lever", meaning "to raise". The verb, in turn, goes back to the Latin "levare", itself from the adjective "levis", meaning "light" (as in "not heavy"). The word's primary origin is the Proto-Indo-European (PIE) stem "legwh-", meaning "light", "easy" or "nimble", among other things. The PIE stem also gave rise to the English word "light". The earliest remaining writings regarding levers date from the 3rd century BCE and were provided by Archimedes. 'Give me