The need for core springs is even greater during fast motions and
high accelerations as shown in Figure 11. Without
core springs, when the character stops abruptly, the high acceleration
causes the curls to unwind. It is important to note that
the length of the hair segments themselves are not extending much
here, rather the curls are unwinding, resulting in a visually longer
hair. Using core springs, the curls maintain the shape much better.
These extreme, non-physical accelerations are not uncommon
when dealing with animated films.