A simple pendulum is placed at a place where its distance from the earth's surface is equal to the radius of the earth. If the length of the string…

A simple pendulum is placed at a place where its distance from the earth's surface is equal to the radius of the earth. If the length of the string is $\displaystyle 4 m$, then the time period of small oscillations will be $\displaystyle \_\_\_\_$ s. [take $\displaystyle g=\pi^2 m s^{-2}$ ]