A body of mass m kg. starts falling from a point 2R above the Earth's surface. Its kinetic energy when it has fallen to a point 'R' above the Earth's surface [R-Radius of Earth, M-Mass of Earth, G-Gravitational Constant]
Potential energy U=−GMmr=GMmR+h
Uinitial=−GMm3R and Ufinal=−−GMm2R
Loss in PE=gain in KE=GMm2R−GMm3R=GMm6R