| A
simple machine is any device that only requires the application of a single
force to work. Simple
machines all convert a smaller amount of
force exerted over a larger distance to a greater amount of force exerted over
a shorter distance, or vice versa. The
ratio of the output force to the input force is the called mechanical advantage. The mechanical advantage
of a lever is equal to the ratio of its two arms. For example, the mechanical
advantage of an inclined plane (with the force acting parallel to the plane) is
the cosecant of the angle of inclination. - Note:
Real machines are also affected by factors such as friction and elasticity, so
the actual mechanical advantage of a simple machine will usually differ from its
theoretical value.
Simple
machines are often used in combination as components of more complex machines;
for example the Archimedes screw, which is a pump, is an example of a complex
machine where the screw is a helical inclined plane. | |
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