单词	lever
释义	lever A simple machine consisting of a rigid bar pivoted about a fulcrum. The mechanical advantage or force ratio of a lever (the ratio of load to effort) is equal to the ratio of the perpendicular distance of the line of action of the effort from the fulcrum to the perpendicular distance of the line of action of the load from the fulcrum. In a first-order lever the fulcrum comes between load and effort. In a second-order lever the load comes between the fulcrum and the effort. In a third-order lever the effort comes between the fulcrum and the load. See illustrations. Levers
随便看	diamond diaphragm diastereoisomers dichroism dielectric dielectric constant dielectric heating Diesel engine differential amplifier differential calculus differential equation differential geometry differentiation diffraction diffraction grating diffusion diffusion cloud chamber diffusion limited aggregation diffusion pump digit digital audio tape digital computer digital display digital recording digitron

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