The force between two system is inversely proportional to the square the distance between them. The indirect proportion between these items may be expressed as,
F = k / d²
where k is the constant proportionality. Substituting the known values,
0.68 N = k / (1 m)² ; k = 0.68
For the second case,
F = 0.68 / (0.5 m)² = 2.72 N
Thus, the answer is 2.72 N.
