Inclined
Plane a simple machine
used to raise or lower a load by rolling or
sliding
The secret of the inclined
plane's mechanical advantage is that for an
object resting on the plane the vertical force of
gravity acting on it is split into two smaller
forces, one perpendicular to, one parallel to the
plane. And it is only the parallel force which
needs to be counteracted by pushing. If there is
no friction on the plane, the pushing effort
required will be one tenth the weight if the
length of the plane is 10 times its height. Just
as with a lever, pulley, or wheel and axle,
any decrease in force is accompanied by a
reciprocal increase in the distance.
The diagrams below show a man
pushing a cylinder weighing 60 pounds up an
inclined plane. The ratio of the triangle's
height to its hypoteneuse determines how much
effort (arrows) the man must exert to move the
cylinder up the plane at a uniform speed. Top:
the answer is one half, or 30 pounds. Middle: one
third of 60, or 20 pounds. Bottom: one quarter of
60, or 15 pounds.
Robert O'Brien Machines
New York: Time Incorporated, 1964
The World Book Encyclopedia
Chicago: World BookChildcraft International,
1979
Lever
Pulley
Wheel and Axle
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