BRAVO! That's the right answer!
Fg = (6.67 x 10 - 11 N m2/kg2) (108 kg)2/(40 m)2
Fg = (6.67 x 10 - 11) (108)2/(40)2 N
Fg = 420 N
A force of 420 N has very little effect on a one-hundred-thousand-ton oceanliner!
(c) 2003, Doug Davis; all rights reserved.