If the gravitational force between two objects is proportional to $1/R$,where $R$ is the distance between the two objects,then the orbital speed $v$ is proportional to which of the following?

Suppose the gravitational force varies inversely as the $n^{th}$ power of the distance. Then,the time period of a planet in circular orbit of radius $R$ around the sun will be proportional to

Two satellites $A$ and $B$ of masses $200 \, kg$ and $400 \, kg$ are revolving around the Earth at heights of $600 \, km$ and $1600 \, km$ respectively. If $T_{A}$ and $T_{B}$ are the time periods of $A$ and $B$ respectively,then find the value of $T_{B} - T_{A}$.
[Given: Radius of Earth $R = 6400 \, km$,Mass of Earth $M = 6 \times 10^{24} \, kg$,$G = 6.67 \times 10^{-11} \, Nm^{2}/kg^{2}$]

What is the orbital velocity of a satellite? Derive its equation.

$A$ geostationary satellite is orbiting the earth at a height of $6R$ from the earth's surface ($R$ is the earth's radius). What is the period of rotation of another satellite at a height of $2.5R$ from the earth's surface?

Using the data given below,find the height at which a communication satellite can reside. $(G=6.67 \times 10^{-11} \text{ N-m}^2 \text{ kg}^{-2}, M=5.98 \times 10^{24} \text{ kg}, R=6.4 \times 10^6 \text{ m})$ (in $\text{ km}$)