How much force of gravitation acts on a body at an infinite distance from the Earth?

Who among the following gave the first experimental value of $G$?

$A$ gravitational field is present in a region and a mass is shifted from $A$ to $B$ through different paths as shown. If $W_1, W_2$ and $W_3$ represent the work done by the gravitational force along the respective paths,then

The gravitational force between two identical uniform solid gold spheres of radius $r$ placed in contact is proportional to:

Find the acceleration of our galaxy due to the nearest comparably sized galaxy. The approximate mass of each galaxy is $8 \times 10^{11}$ solar masses,and they are separated by $2 \times 10^6$ light-years. Each galaxy has a diameter of $10^5$ light-years. (Assume $1 \text{ light-year} \approx 10^{16} \text{ m}$,gravitational constant $G \approx 10^{-10} \text{ Nm}^2/\text{kg}^2$,and mass of the Sun $= 2.0 \times 10^{30} \text{ kg}$)

$A$ 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?