Practice question

Young's modulus: Y = FLAΔL. Rearrange: ΔL = FLAY. Substitute: ΔL = 400×2.64×10−6×9×1010 = 10403.6×105≈2.89×10−3m = 2.89mm. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.89mm. This satisfies dimensional consistency and physical conditions given, so option D is scientifically correct.