If the mass of two bodies is doubled and the distance between them is also doubled,what happens to the new gravitational force?

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

Two particles each of mass $m$ are placed at points $P$ and $Q$ as shown in the figure. $R$ is the mid-point of $PQ = l$. The gravitational force on the third particle of mass $m$ placed at point $S$ on the perpendicular bisector of $PQ$ is

Two solid spheres each of radius $R$ made of the same material are placed in contact with each other. If the gravitational force acting between them is $F$,then:

We can shield a charge from electric fields by putting it inside a hollow conductor. Can we shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means?

Two bodies of masses $8 \,kg$ are placed at the vertices $A$ and $B$ of an equilateral triangle $ABC$. $A$ third body of mass $2 \,kg$ is placed at the centroid $G$ of the triangle. If $AG=BG=CG=1 \,m$, where should a fourth body of mass $4 \,kg$ be placed, so that the resultant force on the $2 \,kg$ body is zero?