The modulus of elasticity is typically expressed in which unit?

The modulus of elasticity is a measure of a material's ability to deform elastically when a force is applied. It quantifies the relationship between stress (force per unit area) and strain (proportional deformation) in a material. This relationship is vital in engineering applications as it helps predict how materials will respond under various loads.

The correct unit for expressing the modulus of elasticity is kilopascals (kPa), which is a unit of pressure or stress. Since modulus of elasticity concerns how much stress can be applied before causing significant deformation, it is inherently tied to units of pressure, where 1 pascal is defined as one newton per square meter. Therefore, expressing the modulus of elasticity in kPa allows engineers to clearly communicate how much load a material can handle elastically.

Other options such as joules, newtons per second, and newtons per hour do not relate to the definition of modulus of elasticity. Joules measure energy, while newtons per second and newtons per hour suggest a rate of force, neither of which aligns with the concept of stress or elasticity in materials. Hence, kPa is the appropriate and standardized unit for expressing the modulus of elasticity.