A ball with no kinetic or potential energy (shown in grey at the start of the animation) is raised up (blue arrow) against gravity. This force x distance is stored as potential energy (ball is now blue). As the support disappears, the ball rolls down the slope, losing its potential energy (blue) and gaining kinetic energy (red). Once it reaches the ground, all its potential energy has been converted to movement (kinetic energy). There will be some losses due to friction, air resistance, and heat, which is why the ball slows as it rolls across the ground.