Viscosity — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Viscosity.

Comparative analysis of terminal velocity under varying conditions

high

NEET frequently tests proportionality and comparative analysis. A question might involve two spheres of different radii or densities, or falling in fluids of different viscosities, and ask for the ratio of their terminal velocities. This requires a solid understanding of the terminal velocity formula and its dependencies ($v_t \propto r^2$, $v_t \propto (\rho - \rho_f)$, $v_t \propto 1/\eta$). Students often make mistakes with the square of the radius or the density difference, making it a good differentiator.

Conceptual questions on the effect of temperature on viscosity for liquids vs. gases

high

This is a classic conceptual distinction that highlights the molecular basis of viscosity. Questions often ask why liquid viscosity decreases with temperature while gas viscosity increases, or present scenarios where this knowledge is applied. It tests fundamental understanding rather than just formula application. Misconceptions about this topic are common, making it a reliable area for NEET to probe conceptual clarity.

Application of Newton's Law of Viscosity in simple shear flow scenarios

medium

While terminal velocity is more common, a direct application of Newton's Law of Viscosity ($\tau = \eta \frac{dv}{dy}$) to calculate shear stress or viscous force in a simple parallel plate setup could appear. This tests the basic definition and understanding of the velocity gradient and shear stress. It's a foundational concept that ensures students understand the origin of viscosity before moving to more complex applications like Stokes' Law.