What is Young's modulus a measure of?

Young's modulus is a fundamental property of materials that quantifies their stiffness. It is defined as the ratio of tensile stress (force per unit area) to tensile strain (deformation expressed as a percentage of the original length) in a material when it is subjected to elastic deformation. This property is crucial because it helps predict how much a material will deform under a given load, allowing engineers and designers to select appropriate materials for various applications based on their stiffness characteristics.

A higher Young's modulus indicates a stiffer material that deforms less under load, while a lower value suggests a material that will deform more easily. Understanding the stiffness provided by Young's modulus is essential in applications ranging from structural engineering to the design of everyday products, ensuring they can withstand applied forces without excessive deformation.

The other options relate to different material properties: toughness describes a material’s ability to absorb energy before fracturing, ductility indicates how much a material can be stretched or deformed before breaking, and thermal expansion refers to how much a material expands when heated. These properties, while important, do not directly relate to the measure of stiffness that Young’s modulus represents.