Earth has mass $8$ times and radius $2$ times that of a planet. If the escape velocity from the Earth is $11.2 \ km/s$,the escape velocity in $km/s$ from the planet will be:

The escape velocity of a rocket launched from the surface of the earth:

If the Earth has a mass nine times and a radius twice that of a planet $P$. Then $\frac{v_e}{3} \sqrt{x} \; ms^{-1}$ will be the minimum velocity required by a rocket to escape the gravitational force of $P$,where $v_e$ is the escape velocity on Earth. The value of $x$ is

If the radius of a planet is $R$ and its density is $\rho$,the escape velocity from its surface will be

$A$ spaceship moves from the Earth to the Moon and back. The greatest energy required for the spaceship is to overcome the difficulty in:

$A$ particle is kept at rest at a distance $R$ from the surface of the Earth (of radius $R$). The minimum speed with which it should be projected so that it does not return is