Practice question
Question
A torque of 18Nm acts on a disk with moment of inertia 6kg m2 starting from rest. What is its angular speed after 4s?
Explanation
α = τI = 186 = 3rad/s2. ω = ω0+αt = 0+3×4 = 12rad/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 12 rad/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.