Answer:
Kevin is using the principle of Timing. This principle is proportional to the Speed of the objects displayed.
Explanation:
Timing is one of the principles of animation wherein the speed of the movement of an object is controlled by the animator and made to harmonize with certain effects such as sounds. In an example of some projected balls we find that when getting to the peak, their movement is slower compared to when they are coming down.
Speed plays a key role here. This is similar to the slowly falling leaf. Speed and timing are major considerations. When paired with good sounds, the animation comes off better.
