If a particle of mass $m$ is moving in a horizontal circle of radius $r$ with a centripetal force $(-k/r^2)$,the total energy is

$A$ satellite of mass $m$ is in a circular orbit of radius $2R_E$ around the Earth. The energy required to transfer it to a circular orbit of radius $4R_E$ is (where $M_E$ and $R_E$ are the mass and radius of the Earth,respectively).

Obtain an expression for the total energy of a satellite revolving around the Earth.

The total energy of a circularly orbiting satellite is

The additional kinetic energy to be provided to a satellite of mass $m$ revolving around a planet of mass $M$ to transfer it from a circular orbit of radius $R_1$ to another of radius $R_2$ $(R_2 > R_1)$ is:

$A$ satellite is revolving around a planet of mass $M$ in an elliptical orbit of semi-major axis $a$. What is the speed of the satellite when it is at a distance $a/2$ from the planet?