Acceleration due to gravity iquation solve

Whenever an object falls towards the earth, an acceleration is involved. This acceleration is due to the earth's gravitional pull and is called acceleration due to gravity. It is denoted by g. Its SI unit is m/s sq. Let mass of the earth be M and an object falling freely towards it be m . The distance between centres of the earth and the object is R. From newton's law of gravitation, F=GMm _____ ......1. R2 Also, from second law of motion, force exerted on an object, F=ma Since, a =g (i.e. acceleration due to gravity ) F=mg .........2. Equating RHS of Eq.1 and 2,we get mg=GMm g=GM _____ Or ____ R2 R2