Supposing Newton’s law of gravitation for gravitation forces F1 and F2 between two masses m1 and m2 at positions r1 and r2 read F1 = -F2 = -(r12/r123)GMo2(m1m2/Mo2)n where M0 is a constant of dimension of mass, r12 = r1 – r2 and n is a number. In such a case,
(a) the acceleration due to gravity on earth will be different for different objects.
(b) none of the three laws of Kepler will be valid.
(c) only the third law will become invalid.
(d) for n negative, an object lighter than water will sink in water.