Consider a planet in some solar system which has a mass double the mass of earth and density equal to the average density of earth. If the weight of an object on earth is ${W}$, then weight of the same object on that planet will be

If earth suddenly stop rotating, then the weight of an object of mass $m$ at equator will $[\omega$ is angular speed of earth and $R$ is its radius]

If the angular velocity of earth's spin is increased such that the bodies at the equator start floating, the duration of the day would be approximately …….. minutes

(Take : $g =10 \,ms ^{-2},$ the radius of earth, $R =6400 \times 10^{3}\, m ,$ Take $\left.\pi=3.14\right)$

The radii of two planets are respectively ${R_1}$ and ${R_2}$ and their densities are respectively ${\rho _1}$ and ${\rho _2}$. The ratio of the accelerations due to gravity at their surfaces is

A body has a weight $90\, kg$ on the earth's surface, the mass of the moon is $1/9$ that of the earth's mass and its radius is $1/2$ that of the earth's radius. On the moon the weight of the body is ………. $kg$