JEE Main 2021 — Gravitation Question with Solution

Suppose two planets (spherical in shape) of radii $R$ and $2R,$ but mass $M$ and $9M$ respectively have a centre to centre separation $8R$ as shown in the figure. A satellite of mass $m$ is projected from the surface of the planet of mass $M$ directly towards the centre of the second planet. The minimum speed $v$ required for the satellite to reach the surface of the second planet is $\sqrt{\frac{\mathrm{a}}{7}\frac{\mathit{G}\mathit{M}}{\mathit{R}}}$, then the value of  $a$ is
[Given : The two planets are fixed in their position]