A uniform rod AB of mass 2 kg and length 30 cm at rest on a smooth horizontal surface. An impulse of force 0.2 Ns is applied to end B. The time taken…

A uniform rod AB of mass $\displaystyle 2$ kg and length $\displaystyle 30$ cm at rest on a smooth horizontal surface. An impulse of force $\displaystyle 0.2$ Ns is applied to end B . The time taken by the rod to turn through at right angles will be $\displaystyle \frac{\pi}{x} \mathrm{~s}$, where $\displaystyle x=$ $\displaystyle \_\_\_\_$.