If $r$ represents the radius of the orbit of a satellite of mass $m$ moving around a planet of mass $M$,the velocity of the satellite is given by

Two satellites of mass $50\,kg$ and $100\,kg$ revolve around the earth in circular orbits of radius $9\,R$ and $16\,R$ respectively,where $R$ is the radius of the earth. The ratio of the speeds of the two satellites will be:

Why does a satellite not have an escape velocity?

If $g \propto \frac{1}{R^3}$ (instead of $\frac{1}{R^2}$),then the relation between the time period $T$ of a satellite near the Earth's surface and the radius $R$ will be:

Shown are several curves [fig. $(a)$,$(b)$,$(c)$,$(d)$,$(e)$,$(f)$]. Explain with reason,which ones amongst them can be possible trajectories traced by a projectile (neglect air friction).

$A$ comet orbits the Sun in a highly elliptical orbit. Does the comet have a constant $(a)$ linear speed,$(b)$ angular speed,$(c)$ angular momentum,$(d)$ kinetic energy,$(e)$ potential energy,$(f)$ total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the Sun.