A metal wire is stretched by suspending weight to it. If X is the longitudinal strain and Y is the Young’s modulus of elasticity, then the elastic potential energy per unit volume is
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Elastic potential energy per unit volume (U) is the energy stored due to deformation. For a wire under tension, it is given by U = (1/2) × Stress × Strain. Stress is related to strain by Young's modulus Y: Stress = Y × Strain (X). Substituting, U = (1/2) × (Y × X) × X = (1/2) Y X².
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