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

$A$ 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

The force of gravitation is

Four identical particles of mass $m$ are kept at the four corners of a square. If the gravitational force exerted on one of the masses by the other masses is $\left(\frac{2 \sqrt{2}+1}{32}\right) \frac{Gm^2}{L^2}$,the length of the sides of the square is

Two concentric shells of uniform density of mass $M_1$ and $M_2$ are situated as shown in the figure. The forces experienced by a particle of mass $m$ when placed at positions $A, B$ and $C$ respectively are (given $OA = p, OB = q$ and $OC = r$):

Six point masses of mass $m$ each are at the vertices of a regular hexagon of side $l$. Calculate the net gravitational force on any one of the masses.