question_answer

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 \[\theta ,\]where \[\theta \] is the angle by which it has rotated, is given as \[k{{\theta }^{2}}.\]If its moment of inertia is I then the angular acceleration of the disc is :                                                       [JEE Main 9-4-2019 Morning]

A)  \[\frac{k}{2I}\theta \]                

B)       \[\frac{k}{I}\theta \]

C)  \[\frac{k}{4I}\theta \]                

D)       \[\frac{2k}{I}\theta \]

Correct Answer: D

Solution :

[d] Kinetic energy

(1)

Differentiate (1) wrt time

Option [d]