Mōd'ŭ-lŭs, n.

Mōd'ŭ-lŭs, n. [Lat.] (Mech. & Physics.) A quantity or co-efficient, which expresses the measure of some specified force, property, or quality, as of elasticity, strength, efficiency, &c.

Modulus of a machine, a formula expressing the work which a given machine can perform under the conditions involved in its construction; the relation between the work done upon a machine by the moving power, and that yielded at the working points, either constantly, if its motion be uniform, or in the interval of time which it occupies in passing from any given velocity to the same velocity again, if its motion be variable; — called also the efficiency of the machine. Moseley. Rankine. — Modulus of a system of logarithms (Math.), a number by which all the logarithms in one system of notation must be multiplied, to adapt them to the same number in another system. — Modulus of elasticity, the measure of the elastic force of any substance, expressed by the ratio of a pressure on a given unit of the substance to the accompanying compression; or, an expression of the force (usually in terms of the height in feet or weight in pounds of a column of the same body) which would be necessary to elongate a prismatic body of a transverse section equal to a given unit, as a square inch or foot, to double, or to compress it to half its original length, were that degree of elongation or compression possible, or within the limits of elasticity. — Modulus of rupture, the measure of the force necessary to break a given substance, as a beam, expressed by eighteen times the load which is required to break a bar of one inch square, supported at two points one foot apart, and loaded in the middle between the points of support. Rankine.