Practice question
Question
A steel wire of length 2.4m and cross-sectional area 4×10−6m2 is stretched by 0.6mm. If the Young's modulus of steel is 2×1011N/m2, what is the stress?
Explanation
Strain: Strain = ΔLL = 0.6×10−32.4 = 2.5×10−4. Young's modulus: Y = StressStrain. Stress: Stress = Y×Strain = 2×1011×2.5×10−4 = 5×107N/m2. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 5×107N/m2. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.