Wirehair: Gravity effects all objects in exactly the same way. All objects, regardless of weight , will fall at exactly the same speed assuming that there are no other forces at work (like air resistance). In a vacuum chamber, a feather and a hammer will fall at the same ever increasing speed: approximately 9.8 meters per second squared.

The tilt compensated rangefinders just do a bit of electronic geometry for you to calculate the horizontal distance to the target which is the determining factor in arrow drop. The angled line of sight distance might be 35 yards, but the horizontal distance might only be 30 yards so you would use you 30 yard pin for an accuarate shot.