Perpetual Motion? Gravity? Myself and someone who can't speak english very well want to know!?

If you dropped a ball through a giant hole in the Earth (which, mind you, cannot exist, but anyway...) The ball would begin to fall. As it fell, it would be gaining speed, from the acceleration due to gravity... however, the force would begin to decrease as it fell, linearly. Since the farther you fall down, the more Earth you leave behind you, which exerts it's pull on you in the opposite direction, thus reducing the acceleration. By the time you reach the center, you will be at your maximum velocity, but the gravitational force on you will be effectively zero. Of course, you will continue moving, thus being slowed down by the same gravitational force, which is now increasing. By the time you reach the other side of the hole, you would have no velocity at all. This scenario, however, is ignoring air resistance, which would probably hinder perpetual motion, if this hole was even possible to construct.