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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Lever
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INFOTEXT
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1992-09-03
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A simple machine consisting of a rigid rod
pivoted at a fixed point called the fulcrum,
used for shifting or raising a heavy load or
applying force in a similar way. Levers are
classified into orders according to where the
effort is applied, and the load-moving force
developed, in relation to the position of the
fulcrum. A first-order lever has the load and
the effort on opposite sides of the fulcrum -
for example, a see-saw or pair of scissors. A
second-order lever has the load and the
effort on the same side of the fulcrum, with
the load nearer the fulcrum - for example,
nutcrackers or a wheelbarrow. A third-order
lever has the effort nearer the fulcrum than
the load with both on the same side of it -
for example, a pair of tweezers or tongs. The
mechanical advantage of a lever is the ratio
of load to effort, equal to the perpendicular
distance of the effort's line of action from
the fulcrum divided by the distance to the
load's line of action. Thus tweezers, for
instance, have a mechanical advantage of less
than one.