Final answer:
The 'stiffness' of lumber is known as modulus of elasticity or Young's modulus. It represents the material's ability to resist bending or sagging under load. The modulus of elasticity helps determine the maximum allowable span for a given piece of lumber.
Step-by-step explanation:
The 'stiffness' of lumber is known as modulus of elasticity or Young's modulus. It is a measure of how much a material will deform under tensile stress. For lumber, the modulus of elasticity represents the ability of the material to resist bending or sagging under load.
The 'stiffness' of lumber is associated with its tensile strength, which is the breaking stress leading to permanent deformation. It involves the modulus of elasticity, cross-sectional area, and the material's lengths both stretched and relaxed.
The "stiffness" of lumber refers to its ability to resist deformation under load, which is closely related to the concept of tensile strength. Tensile strength is defined as the breaking stress that will cause permanent deformation or fraction of a material. It involves the product of the three-dimensional modulus of elasticity (E) and the cross-sectional area (A), which together comprise the effective one-dimensional modulus of the material. The actual stretched length (L) and the relaxed length (L0) of the lumber are also taken into account.
When a force is applied to lumber, it experiences tensile stress which tries to stretch the material. If the stress exceeds the material's breaking point, permanent deformation or fracture can occur. The modulus of elasticity helps determine the maximum allowable span for a given piece of lumber, indicating its strength and stiffness.
For a given span, higher modulus of elasticity values indicate that the lumber is stiffer and can support heavier loads without excessive bending or sagging. Lower values suggest that the lumber is less stiff and should be used for shorter spans or lighter loads.