An earth satellite $X$ is revolving around earth in an orbit whose radius is one-fourth of the radius of orbit of a communication satellite. Time period of revolution of $X$ is ……….

The distance between Sun and Earth is $R.$ The duration of year if the distance between Sun and Earth becomes $3R$ will be 

If the earth suddenly shrinks to $\frac{1}{64}$ th of its original volume with its mass remaining the same, the period of rotation of earth becomes $\frac{24}{ x } h$. The value of $x$ is $…….$

If $r$ denotes the distance between the sun and the earth, then the angular momentum of the earth around the sun is proportional to

The maximum and minimum distances of a comet from the Sun are $1.6 \times 10^{12}\, m$ and $8.0 \times 10^{10}\, m$ respectively. If the speed of the comet at the nearest point is $6 \times 10^{4}\, ms ^{-1},$ the speed at the farthest point is ……… $\times 10^{3}\, m / s$