According to the universal law of gravitation, gravitational force (F) acting between two objects is inversely proportional to the square of the distance (r) between them, i.e.,
f ∝ 1 / r 2
If distance r becomes r/2, then the gravitational force will be proportional to
1 / ( r/2 ) 2 = 4 / r 2
Hence, if the distance is reduced to half, then the gravitational force becomes four times larger than the previous value.
