(c) $V_{in} = \frac{- GM}{2R}\left\lbrack 3 - \left( \frac{r}{R} \right)^{2} \right\rbrack,V_{surface} = \frac{- GM}{R},V_{out} = \frac{- GM}{r}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.