12 Principles of Animation Pt.3

Arc:
This is the belief that the most natural action tends to follow an arced trajectory. Think of a lobbed basketball as someone shoots it.
Secondary Action:
Secondary action is the principle of adding reacting motion to a primary motion to give it more of a realistic effect. Think of a dog shaking to dry off. An example of secondary action would be the dogs ears flapping as he shakes.
Timing:
Timing is the number of frames applied to a part of animation to change the speed of said animation. Using less frames would equate to a faster moving animation, while using more frames would make a slower moving animation.