The self gravitational potential energy of a spherical shell of mass $M$ and radius $R$ is

Two satellites, $A$ and $B,$ have masses $m$ and $2\,m$ respectively. $A$ is in a circular orbit of radius $R,$ and $B$ is in a circular orbit of radius $2R$ around the earth. The ratio of their kinetic energies, $K.E._A / K.E._B ,$ is

A stationary object is released from a point $P$ at a distance $3 R$ from the centre of the moon which has radius $R$ and mass $M$. Which of the following gives the speed of the object on hitting the moon?

If $g$ is the acceleration due to gravity on the earth's surface, the gain in the potential energy of an object of mass m raised from the surface of earth to a height equal to the radius of the earth $R$, is

A satellite of earth of mass $'m'$ taken from orbital radius $2R$ to $3R,$ then minimum work done