The Physics of Materials: Strength, Stress, and Strain

Stress measures the internal force per unit area inside a material.
Strain describes how much a material deforms when stress is applied.
Elastic materials return to their original shape once the stress is removed.
Plastic deformation occurs when a material is permanently bent or stretched.
The stress–strain curve shows how materials behave under load.
Young’s modulus quantifies stiffness—the ratio of stress to strain.
Toughness measures how much energy a material can absorb before breaking.
Metals are strong yet ductile, while ceramics are hard but brittle.
Engineers study stress and strain to design safer buildings, bridges, and machines.
Understanding these properties lets us tailor materials for strength and durability.