Practice question
Question
A brass block of dimensions 0.4m×0.3m×0.1m is subjected to a shearing force of 3×104N. If the shear modulus of brass is 3.6×1010N/m2, what is the displacement of the top face?
Explanation
Shear modulus: G = F/AΔx/L. Rearrange: Δx = FLAG. Area: A = 0.4×0.3 = 0.12m2, L = 0.1m. Substitute: Δx = 3×104×0.10.12×3.6×1010 = 30004.32×109≈6.94×10−7m. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 6.94×10−7m. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.