A solid cylinder of mass 2 kg and radius 4 cm rotating about its axis at the rate of 3 rpm. The torque required to stop after 2π revolution is

ω0 = 3 rpm = 3×2π60rad/sec = π10 rad/secUsing, ω2= ωo2+2αθ02 = (π10)2+ 2(α)(2π×2π)α =- 1800rad/sec2Torque, τ = Iα= 12×2×0.042 (-1800) N-m = -2×10-6 N-mNegative sign indicates that the applied torque is retarding in nature