A sphere of radius 0.07m moves at 0.14m/s through honey (η\=0.2Pa s). What is the viscous drag force?
Stokes’ law: F = 6πηav. η = 0.2Pa s, a = 0.07m, v = 0.14m/s. F = 6×3.14×0.2×0.07×0.14 = 0.0369N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 0.036 N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.