A 67 kg solid sphere with a 51 cm radius is suspended by a vertical wire. A torque of 0.40 N · m is required to rotate the sphere through an angle of 0.90 rad and then maintain that orientation. What is the period of the oscillations that result when the sphere is then released?

The moment of Inertia, I of solid sphere is equal to 2/5 MR^2

The period T is equal to 2*pi*(I/Kappa)^(1/2)

The Torque is equal to a negative Kappa times Theta.

For I, I get 6.9707 and for Kappa I get 44.44 so the period is 2.488 seconds, but the book says it is wrong.

Please help - Thanks!!!