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In chemistry, the lever rule is a formula used to determine the mole fraction (x i) or the mass fraction (w i) of each phase of a binary equilibrium phase diagram.It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line.
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 fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists.
The lever is operated by applying an input force F A at a point A located by the coordinate vector r A on the bar. The lever then exerts an output force F B at the point B located by r B. The rotation of the lever about the fulcrum P is defined by the rotation angle θ. This is an engraving from Mechanics Magazine published in London in 1824.
A lever arm uses the fulcrum to lift the load using and intensifying an applied force.In practice, conditions may prevent the use of a single lever to accomplish the desired result, [1] e.g., a restricted space, the inconvenient location of the point of delivery of the resultant force, or the prohibitive length of the lever arm needed.
Engraving from an 1824 mechanics magazine illustrating Aristotle's statement that given a place to stand, with a lever a person could move the Earth. The idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines: lever, pulley, and screw.
There are two books to On the Equilibrium of Planes: the first contains seven postulates and fifteen propositions, while the second book contains ten propositions. In the first book, Archimedes proves the law of the lever, which states that: Magnitudes are in equilibrium at distances reciprocally proportional to their weights.
In physics and engineering, a free body diagram (FBD; also called a force diagram) [1] is a graphical illustration used to visualize the applied forces, moments, and resulting reactions on a free body in a given condition. It depicts a body or connected bodies with all the applied forces and moments, and reactions, which act on the body(ies).
As Archimedes had previously shown, the center of mass of the triangle is at the point I on the "lever" where DI :DB = 1:3. Therefore, it suffices to show that if the whole weight of the interior of the triangle rests at I, and the whole weight of the section of the parabola at J, the lever is in equilibrium.