A non conducting uniform thin shell of mass $m$ and radius $R$ has uniform charge density $+\sigma$  on one half and  $-\sigma$ on another half as shown in figure. It is placed on a rough non conducting horizontal plane. At t = 0 a uniform electric field $\overrightarrow{E}=E_0\widehat{j}N/C$ is switched on and the solid sphere starts rolling without slipping . The speed of center of the sphere when it rotates through an angle of 53⁰ is $\sqrt{\frac{n\pi R^3{\sigma }_0{E}_0}{m}}$. Find $n$.