Solution:
Solution
The kinetic energy at altitude $$2R= \large\frac{GMm}{6R}$$
The gravitational potential energy at altitude $$2R= \large\frac{-GMm}{3R}$$
Total energy =$$=k \in +PE=-\large\frac{GMm}{6R}$$
Potential energy at the surface is $$\large\frac{-GMm}{R}$$
∴Req. kinetic energy = $$\large\frac{GMm}{R}-\frac{GMm}{6R};=$$
$$\qquad=\large\frac{5GMm}{6R}$$