Gravitational forces operate among which of the following?

The distance between two objects $A$ and $B$ is $r$. The gravitational force between them is inversely proportional to the square of the distance. If the gravitational force between these two objects were inversely proportional to the fourth power of the distance,find the acceleration of object $A$.

The gravitational force $F_g$ between two objects does not depend on

$A$ suitable unit for gravitational constant is

Three particles each of mass $M$ are placed at the three corners of an equilateral triangle of side $l$. What is the gravitational force due to this system of particles on another particle of mass $m$ placed at the midpoint of any side?

Two point masses $m$ and $4m$ are separated by a distance $d$ on a line. $A$ third point mass $m_0$ is to be placed at a point on the line such that the net gravitational force on it is zero. The distance of that point from the $m$ mass is: