If the force of gravity acts on all bodies in proportion to their masses, why does heavy body not all faster than a light body?

Explanation

(i) If F be the gravitational force on a body of mass m then
`F = (GMm)/(R^2) = mg" " g = (GM)/(R^2)`
(ii) `F prop m` but g does not depend on m. So all bodies fall with same speed if there is no air resistance.