Complex sentence: As an object moves in the direction in which the force accelerates it its potential energy decreases: the gravitational potential energy of a cannonball at the top of a hill is greater than at the base of the hill.
Split into simpler sentences: As an object moves in the direction that the force accelerates it, its potential energy decreases. For example, the gravitational potential energy of a cannonball at the top of a hill is greater than at the base of the hill.