Weight of a body is less in the mines. Why?
The weight of a body is less in the mines because when we move deeper the earth gravity decreases but our mass is always constant.
What will happen to the gravitational force when the mass of each body is doubled and the distance between them is halved?
When the masses of two objects is doubled, then the gravity between them is quadrupled; and so on. Since the gravitational force is directly proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitation forces.