Questions on the "jerk" I have two questions relating to the third derivative of displacement with respect to time. My main question is this. Does a jerk ever occur in the natural universe? I know that there are many situations in which acceleration changes over time, but all that I can think of do not directly relate change in force to time, the all are with respect to position. For example, an object falling towards earth from an extremly long distance or a hooke's law spring. My second question is more complicated. It is pretty obvious that you can not suddenly change velocity. You must first accelerate to reach some final velocity. Does this mean that you can not suddenly reach some acceleration? Must you first undergo some jerk? (I can't believe this easily because this would mean that an object freely falling would have to spend some period of time to reach 9.8 m/(ss)). But if an object does need to have some jerk for some acceleration to be reached, does this mean that in order to have some jerk, you must undergo some fourth derivative of displacement, and some fifth for that, and so on for infinate derivatives? I'm only a high school senior, so try to answer in a way that is not too complicated.