Binding energy of a revolving satellite at height $h$ is $3.5 \times 10^8 \ J$. Its potential energy is

Initially, a satellite of $100 \ kg$ is in a circular orbit of radius $1.5 R_E$. This satellite can be moved to a circular orbit of radius $3 R_E$ by supplying $\alpha \times 10^6 \ J$ of energy. The value of $\alpha$ is . . . . . . .
(Take Radius of Earth $R_E = 6 \times 10^6 \ m$ and $g = 10 \ m/s^2$)

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

$A$ satellite is orbiting the Earth. If its orbital radius is reduced to half of its initial value,then the percentage change in its total energy is: (in $\%$)

An astronaut takes a ball of mass $m$ from Earth to space. He throws the ball into a circular orbit about Earth at an altitude of $318.5 \ km$. From Earth's surface to the orbit,the change in total mechanical energy of the ball is $x \frac{GM_e m}{21 R_e}$. The value of $x$ is (take $R_e = 6370 \ km$).

The figure shows the variation of energy with the orbit radius of a body in circular planetary motion. Find the correct statement about the curves $A, B$ and $C$.