Practice question
Question
An aluminium rod of length 1.4m and cross-sectional area 2×10−6m2 is compressed by a force producing a stress of 3×107N/m2. If the Young's modulus of aluminium is 7×1010N/m2, what is the compression?
Explanation
Young's modulus: Y = StressStrain. Strain: Strain = StressY = 3×1077×1010≈4.29×10−4. Compression: ΔL = Strain×L = 4.29×10−4×1.4≈6×10−4m = 0.6mm. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 0.6mm. This satisfies dimensional consistency and physical conditions given, so option D is scientifically correct.