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An astronaut on the surface of the moon ...

An astronaut on the surface of the moon throws a piece of lunar rock (mass m) directly towards the earth at a great speed such that the rock reaches the earth. Mass of the earth = M, Mass of the moon `=(M)/(81)` Radius of the earth = R, Distance between the centre of the earth and the moon = 60R In the course of its journey calculate the maximum gravitational potential energy of the rock Find the minimum possible speed of the rock when it enters the atmosphere of the earth.

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Verified by Experts

The correct Answer is:
(a) `-(GMm)/(243R)`
(b) `14045/14337 (GMm)/R`
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