Question

The force of attraction between two bodies is 20N Calculate the force between them when mass of each body as well as distance between them is halved ?

Answer 1

F ∝ m / r^2

F1 / F2 = (m1 / m2) * (r2 / r1)^2
F2 = F1 * (r1 / r2)^2 * (m2 / m1)
F2 = F1 * (r1 / (r1/2))^2 * (m1/2 / m1)
F2 = F1 * 4/2
F2 = 2 * F1
F2 = 2 * 20
F2 = 40 N

Force of attraction will become 40 N