Two satellites $A$ and $B$ having ratio of masses $3: 1$ are revolving in circular orbits of radii $r$ and $4r$. The ratio of total energy of satellites $A$ to that of $B$ is

Two stars of masses $M$ and $2M$ are at a distance $d$ apart and are revolving around their common center of mass. The angular velocity of the system of the two stars is ($G$ is the universal gravitational constant).

Which of the following is the evidence to show that there must be a force acting on the earth and directed towards the sun?

$A$ planet moves around the sun in an elliptical orbit with the sun at one of its foci. The physical quantity associated with the motion of the planet that remains constant with time is

$A$ satellite is orbiting around the Earth with an areal speed $v_a$. At what height from the surface of the Earth is it rotating,if the radius of the Earth is $R$?

Two particles of equal mass $m$ move in a circle of radius $r$ under the action of their mutual gravitational attraction. The speed of each particle will be ($G=$ Universal gravitational constant).