Practice question

Rotational KE: K = 12Iω2. Moment of inertia of a disk: I = 12MR2 = 12×2×(0.2)2 = 0.04kg m2. K = 12×0.04×(10)2 = 0.02×100 = 2J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2 J. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.