Modulus

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A quantity or coefficient, or constant, which expresses themeasure of some specified force, property, or quality, as ofelasticity, strength, efficiency, etc.; a parameter. Modulus of amachine, a formula expressing the work which a given machine canperform under the conditions involved in its construction; therelation between the work done upon a machine by the moving power,and that yielded at the working points, either constantly, if itsmotion be uniform, or in the interval of time which it occupies inpassing from any given velocity to the same velocity again, if itsmotion be variable; -- called also the efficiency of the machine.Mosley. Rankine.-- Modulus of a system of logarithms (Math.), a number by which allthe Napierian logarithms must be multiplied to obtain the logarithmsin another system.-- Modulus of elasticity. (a) The measure of the elastic force ofany substance, expressed by the ratio of a stress on a given unit ofthe substance to the accompanying distortion, or strain. (b) Anexpression of the force (usually in terms of the height in feet orweight in pounds of a column of the same body) which would benecessary to elongate a prismatic body of a transverse section equalto a given unit, as a square inch or foot, to double, or to compressit to half, its original length, were that degree of elongation orcompression possible, or within the limits of elasticity; -- calledalso Young's modulus.-- Modulus of rupture, the measure of the force necessary to break agiven substance across, as a beam, expressed by eighteen times theload which is required to break a bar of one inch square, supportedflatwise at two points one foot apart, and loaded in the middlebetween the points of support. Rankine.