Question

if mass of earth is reduce to 1/3 what will be the force of atraction between earth and an object on earth?

Answer 1

g = GM/r^2   If mass becomes 1/3 of its original mass(and  radius doesn't change)   New mass = M/3   Radius = r   New g = G(M/3)/r^2 = GM/3r^2 = g/3   Since gravitational force is reducing to 1/3 of original, force of attraction between earth and an object on earth  will also become 1/3 of the original