A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of θ, where θ is the angle by which is has rotated, is given as kθ2 . If its moment of inertia is I then the angular acceleration of the disc is
(1) k/I θ
(2) k/2I θ
(3) k/4I θ
(4) 2k/I θ
