When an object, like a ball, arcs we need to consider the slow in and out, caused by gravity. When doing this in 3D and motion graphics, we can achieve this effect by keeping the movement in the x axis constant but giving the movement in the y axis a slow in and slow out.
Without an arc in the object the animation can seem very dull and straight, like in pose to pose animation, but with an arc in the movement of an object it can give the animation more character.
Arcs can be added to almost any figure movement, for example if a character is taking a step you should have the body of the figure move up and down in an arc before he even takes his first step. This allows for the animation to flow more and seem a lot more natural and fluid instead of very rigid. If an arc is not applied to the figure walking then the action can seem very dull, when animating with arcs it is important to use exaggeration and anticipation as well to get your figures action across in the animation.
Arcing a ball is one of the first things we learned when animating as it is so vital to the animation and to have an animation look correct, look natural and flow then arcing your objects movements are very important.
One Show that uses arcing a lot is Avatar: The Last Airbender
This show heavily features a lot of martial arts in it as the characters in it use various types to control different elements. With this comes a lot arcing in the characters animations especially with the water bending techniques as it’s very slow moving and mimics the way water moves back and forth. The Airbending technique is quite similar but relies more on the figure being loose and being able to flow with the opponents fighting technique and change direction quickly rather like air. The Airbending is based on the martial arts style of Baguazhang and the Waterbending is based on tai chi.