Q: A particle is moving on a circular path. The angle turned by radius vector is $\theta = \theta_0 (1-e^{-t/3})$ , where θ is in radian and t is in second. The angular acceleration at t = 0 is
(a) 1/3 rad/s2
(b) -1/9 rad/s2
(c) 10 rad/s2
(d) -1/6 rad/s2
Ans: (b)