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This article is about the concept in physics. For the Internet forum software, see Simple Machines Forum.
In physics, a simple machine is any device that only requires the application of a single force to work. Work is done when a force is applied and results in movement over a set distance. The work done is the product of the force and the distance. The amount of work required to achieve a set objective is constant; however the force required can be reduced provided the lesser force is applied over a longer distance. The ratio between the two forces is the mechanical advantage.
The traditional list of simple machines is:
The ratio of the output force to the input force is the mechanical advantage. For example, the mechanical advantage of a lever is equal to the ratio of its two arms. The mechanical advantage of an inclined plane (with the force acting parallel to the plane) is the cosecant of the angle of inclination.
These simple machines fall into two general classes; those dependent on the vector resolution of forces (inclined plane, wedge, screw) and those in which there is an equilibrium of torques (lever, pulley, wheel). Simple machines are often used in combination as components of more complex machines. For example: wheels, axles, levers, and pulleys are all used in the formation of modern bicycles.
Variations to the list of simple machines:
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