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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 k θ 2 . If its moment of inertia is I then the angular acceleration of the disc is -

1. θ I k
2. θ I 2 k
3. θ I 4 k
4. θ I k 2

Correct answer: θ I k 2

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