The density of a new planet is twice that of earth. The acceleration due to gravity at the surface of the planet is equal to that at the surface of earth. If $R$ is the radius of earth,then the radius of the planet would be

$A$ planet has double the mass of the earth. Its average density is equal to that of the earth. An object weighing $W$ on earth will weigh on that planet:

The radius of Earth is about $6400 \,km$ and that of Mars is $3200 \,km$,and the mass of the Earth is about $10$ times the mass of Mars. An object weighs $200 \,N$ on the surface of Earth. Then,its weight on the surface of Mars will be (in $\,N$)

If a hole is bored along the diameter of the earth and a stone is dropped into the hole,what happens to the stone?

There is a planet which is $8$ times more massive and $27$ times denser than the Earth. If $g^{\prime}$ and $g$ are the accelerations due to gravity on the surfaces of the planet and the Earth respectively,then:

Two satellites $P$ and $Q$ are moving in different circular orbits around the Earth (radius $R$). The heights of $P$ and $Q$ from the Earth's surface are $h_p$ and $h_Q$,respectively,where $h_p = R / 3$. The accelerations of $P$ and $Q$ due to Earth's gravity are $g_p$ and $g_Q$,respectively. If $g_p / g_Q = 36 / 25$,what is the value of $h_Q$?