A bullet of 10 g, moving with velocity v, collides head-on with the stationary bob of a pendulum and recoils with velocity 100 m/s. The length of the pendulum is 0.5 m and mass of the bob is 1 kg. The minimum value of  = _____ m/s so that the pendulum describes a circle. (Assume the string to be inextensible and g = 10$\left.\mathrm{m} / \mathrm{s}^2\right)$