Young's Modulus Compared

Young's modulus Y measures a material's stiffness under TENSILE/COMPRESSIVE stress: Y = stress/strain = (F/A)/(ΔL/L).

Units: Pa (N/m²). Reported in GPa for typical solids.

Y values: steel ≈ 200 GPa, copper ≈ 110 GPa, aluminum ≈ 70 GPa, glass ≈ 70 GPa, rubber ≈ 0.01-0.1 GPa, wood (along grain) ≈ 12 GPa.

Wire of length L, cross-section A: extension ΔL = FL/(YA). Stiffer (higher Y) ⇒ smaller ΔL for given F.

Force constant of a wire viewed as a spring: k = YA/L. Long, thin wires are softer; short, thick ones are stiffer.

Used in structural engineering, materials selection, vibration analysis, and acoustics.

Y is approximately constant for moderate strains; varies slightly with temperature.

For composite or anisotropic materials (wood, carbon fibre), Y depends on direction.