Modulus of elasticity

An elastic modulus (also known as modulus of elasticity) is a number that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. The elastic modulus of an object is defined as the slope of its stress–strain curve in the elastic deformation region:<ref>Template:Cite book</ref> A stiffer material will have a higher elastic modulus. An elastic modulus has the form:

<math>\lambda \ \stackrel{\text{def}}{=}\ \frac {\text{stress}} {\text{strain}}</math>

where stress is the force causing the deformation divided by the area to which the force is applied and strain is the ratio of the change in some parameter caused by the deformation to the original value of the parameter. If stress is measured in pascals, then since strain is a dimensionless quantity, the units of λ will be pascals as well.<ref>Template:Cite book</ref>