I'm a psychologist and I'm currently studying physics but, because this is not my field of study, I'm having great difficulties. I am currently studying biological motion and I have to calculate the jerk of my 2D motion data and I don't even know where to start. My data is basically a bunch of coordinates on the x and y axis in time. I'll be using jerk as a measure of the "quantity of acceleration" of my stimuli. The aim is to compare the different jerk values of each of my stimulus (biological vs altered biological stimuli). I have the velocity calculated per frame of my stimuli (i.e. I have a velocity value per time - because time is constant). I used this formula for calculating the velocity: =SQRT((X2-X1)^2+(Y2-Y1)^2)/1/60), where X1 is the initial position of the stimulus on the x axis and X2 is the second position (and so on) and Y1 is the initial position of the Y axis and Y2 is the second position of the Y axis. This is data captured at 60Hz, thus, time variation is constant and is 1/60. Thus, I have the instantaneous velocity per frame calculated. However, I want to calculate the "overall" jerk of my stimuli, kind of a "medium jerk"? How do I do that? Any help would be truly important! Thanks a lot!