Lever
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A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of f
Levers can be used to exert a large force over a small distance at one end by exerting only a small force (effort) over a greater distance at the other.
Archimedes lever, Engraving from Mechanics Magazine, published in London in 1824
Simple lever, fulcrum, and vertical posts
Middle ear
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The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea.
The middle ear matches mechanical impedance, like a lever.
1871 Descent F937.1 fig 03