I train in the sport of weightlifting (i.e., the same event that you see in the Olympics that involves two lifts, the snatch and the clean and jerk). I am planning on using the diagnostic tool of filming my lifts with a camera positioned facing me directly from the side. I then plan to advance the frame of the lift 1 frame at a time (each frame will be 1/30th of a second) and plot the path of the bar (using the center of the bar as the point to track). If you would like to see an example of what I am talking about, please look at this website: bennsweightliftingvideos dot info (this site won't let me post the URL) (click on the link along the side that says "2004 Olympic Trials" and you can play any of the video clips and see the sort of plotting I am talking about). Now, I haven't taken a physics course in something like 20 years, but I would like to be able to calculate (and graph) each moment of force acting on the bar throughout the movement. I will use this information, along with visual cues from watching the lift and the shape of the curve, to help correct flaws in my form, and to train using the correct exercises to perfect where I am weak in the movement. The problem is, I simply cannot remember how to do this. Here is what I will know: *The distance between each data point from frame to frame (I will be able to take take a known size, in this case, the diameter of the bar, and determine the what each pixel equates to). *The time between each date point (1/30th of a second). *The mass of the bar. So can you help a dumb weightlifter figure out how I can graph how much force is acting on the bar from one data point to the next given that we will have a bar moving (from the perspective of the camera) in two dimensions? Thanks for your help.