Elasticitets

Elasticitets is a term used across disciplines to describe two related ideas: the ability of a system to return to its original state after a disturbance, and the degree to which one variable changes in response to a change in another variable. In practice, elasticity is quantified as a relative or percentage change.

In materials science, elasticity refers to the reversible deformation of an object under load. Within the elastic region, stress is proportional to strain, a relationship described by Hooke's law. The constants that measure stiffness are the elastic moduli: Young's modulus for axial stiffness, the shear modulus for shape changes, and the bulk modulus for volumetric changes. The Poisson ratio indicates how dimensions change transversely when stretched. Exceeding the elastic limit results in plastic, permanent deformation.

In economics, elasticity measures responsiveness of one variable to another. The price elasticity of demand, for example, is defined as the percentage change in quantity demanded divided by the percentage change in price. Demand is typically considered elastic if the magnitude exceeds one, and inelastic if it is less than one; the sign is usually negative because price rises tend to reduce quantity demanded. Other related concepts include price elasticity of supply, income elasticity, and cross-price elasticity, which describe responses to income changes and to changes in other goods’ prices, respectively.

Elasticitets has practical applications in engineering design, pricing strategies, economic policy, and market analysis. Its interpretation depends on the context, time scale, and specific system under study, making careful measurement and clear definitions essential.