Torque — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

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

Torque in Rolling Motion

high

Problems involving objects (spheres, cylinders, rings) rolling without slipping on an inclined plane or horizontal surface are highly probable. These questions require a combined application of linear dynamics (Newton's second law for translation) and rotational dynamics (Newton's second law for rotation, \$\tau = I\alpha\$). The friction force often plays a dual role, causing both linear and angular acceleration. Choosing the point of contact as the pivot simplifies torque calculations as the friction force produces no torque about this point. Aspirants should be proficient in relating linear and angular quantities ($a = R\alpha$) and identifying the correct moment of inertia for various shapes.

Rotational Equilibrium with Multiple Forces

medium

Questions involving static equilibrium of rigid bodies, such as a ladder leaning against a wall, a beam supported at two points, or a system of masses on a rod, are perennial favorites. These problems require applying both the conditions for translational equilibrium (net force = 0) and rotational equilibrium (net torque = 0). Students need to correctly identify all forces (gravity, normal forces, friction, tension) and their respective moment arms about a chosen pivot. The choice of pivot can significantly simplify calculations, often by eliminating unknown forces from the torque equation. Expect scenarios with varying angles and distributed masses.

Torque on a Current Loop in a Magnetic Field

medium

While primarily a magnetism topic, the concept of torque is directly applied when calculating the torque experienced by a current-carrying loop placed in a uniform magnetic field. The formula \$\vec{\tau} = \vec{M} \times \vec{B}\$ (where \$\vec{M}\$ is the magnetic dipole moment) is a direct application of the cross product for torque. Questions might involve calculating the torque, the magnetic moment, or the angle of orientation for maximum/minimum torque, or the work done in rotating the loop. This angle tests the understanding of the \$\sin\theta\$ dependence of torque in a different physical context.

Torque and Angular Momentum Conservation

medium

The relationship \$\vec{\tau}_{net} = \frac{d\vec{L}}{dt}\$ is fundamental. Questions might involve scenarios where the net external torque is zero, leading to the conservation of angular momentum. This often occurs when an object's moment of inertia changes (e.g., a person pulling in their arms while spinning, a collapsing star). Problems could also involve calculating the change in angular momentum over a period due to a constant or variable torque. Understanding when angular momentum is conserved and when it changes due to external torque is a key concept tested.