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…

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