Answer:
3/2 R
Explanation:
Let the Mass of man be m, Mass of earth be M.
By Newtons, law of gravitation,
F = GMm/R^2, Where G is gravitational constant
90 = GMm/R^2
When man weighs 40N,
GMm/(New R)^2 = 40
= 4/9 (90)
GMm/(New R)^2 = 4/9 (GMm/R^2)
(New R)^2 = 9/4 R^2
New R = 3/2 R
Therefore, height is 3/2 R
