algebra 2 question check description

Question

The repulsive force f between the north poles of two magnets is inversely proportional to the square of the distance d between them. If the repulsive force is 21 lb when the distance is 6 in., find the repulsive force when the distance is 2 in.

Answer 1

The repulsive force f between the north poles of two magnets is inversely proportional to the square of the distance d between them. If the repulsive force is 21 lb when the distance is 6 in., find the repulsive force when the distance is 2 in.

F = K( m1*m2/d² ) , where K = Constant , m1 and m2 are strengths of two poles

F1 = K( m1*m2)/d1²

F2 = K ( m1*m2)/d2 ²

F1/F2 = d2 ² /d1 ²

21/F2 = 4/36

F2 = 9*21 = 189 lb