If the mass of a body is $M$ on the surface of the earth,the mass of the same body on the surface of the moon is

Gravitational forces operate among which of the following?

Two spheres of masses $m$ and $M$ are situated in air and the gravitational force between them is $F$. The space around the masses is now filled with a liquid of specific gravity $3$. The gravitational force between the bodies will now be

$A$ mass $M$ is split into two parts,$m$ and $(M-m)$,which are then separated by a certain distance. What ratio of $\frac{m}{M}$ maximizes the gravitational force between the two parts?

The tidal waves in the sea are primarily due to

Mass $M$ is divided into two parts $xM$ and $(1-x)M$. For a given separation,the value of $x$ for which the gravitational attraction between the two pieces becomes maximum is