Did you guys forgot school ?
sum of all forces = weight*acceleration
1) black hole thing : considering that the black hole is just really heavy, it has a great attractive force that is stong enough to catch light. now if you take something heavier than light and have it move at light speed, it will not be caught (providing it\'s heavy enough of course).
2) as i cant really see what unmovable could mean i figured out it would be some kind of infinite inertia (not sure it\'s the correct word in english though), so let\'s say an inifinite weight. according to my dear formula and to dfryer\'s note about infinity, you would obtain something infinite, either the unmovable object would move or the force would be \"stoped\", just because infinity - infinity = infinity...