What is the reason a liquid’s terminal velocity depends on its radius when falling through a viscous medium?
Stokes’ law (F = 6πηav) shows that viscous force is proportional to radius (a), while weight (43πa3ρg) depends on a3. At terminal velocity, these balance, making v∝a2. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Viscous force depends on radius. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.