\(k + \left( { - \frac{{GMm}}{R}} \right) = \frac{1}{2}mv_0^2 + \left( { - \frac{{GMm}}{{R + h}}} \right)\)
\(k - \frac{{GMm}}{R} = \frac{1}{2}m\left( {\frac{{Gm}}{{R + 2R}}} \right) - \frac{{GMm}}{{R + 2R}}\)
\(\therefore k = \frac{{5GMm}}{{6R}}\)