The magnitude of gravitational potential energy of the moon-earth system is U with zero potential energy at infinite separation. The kinetic energy of the moon with respect to the earth is K.

Question

Philoid · Accepted Answer

The Earth-moon systems are bound systems, so the total energy has to be negative. The total energy of the system(E) is the sum of the kinetic(K.E.) and potential energy(P.E.) of the system. We know that the K.E. can never be negative. Hence, P.E. has to negative and it magnitude should be greater than the K.E.

Therefore, P.E. >K.E.