A body weighs $700\, gm$ weight on the surface of the earth. How much will it weigh on the surface of a planet whose mass is $\frac{1}{7}$ and radius is half that of the earth ...... $gm\, wt$

A hemisspherical shell of mass $2M$ and radius $6R$ and a point mass $M$ are performing circular motion due to their mutual gravitational interaetion Their positions are shown in figure at any moment of time during motion. If $r_1$ and $r_2$ are the radii of circular path of hemispherical shell and point mass respectively and ${\omega _1}$ and  ${\omega _2}$ are the angular speeds of hemi-spherical shell and point mass respectively, then choose the correct option

A satellite revolves in the geostationary orbit but in a direction east to west. The time interval between its successive passing about a point on the equator is ........ $hrs$

$Assertion$ : A balloon filled with hydrogen will fall with acceleration $\frac{g}{6}$ of the moon

$Reason$ : Moon has no atmosphere.

An iron ball and a wooden ball of the same radius are released from a height $‘h’$ in vacuum. The time taken by both of them to reach the ground is equal is based on 

The weight of a body at the centre of the earth is