![]() ![]() This will decrease your "angular mass" (moment of inertia) and increase your angular velocity so that your angular momentum is constant. You can increase your rotation rate if you need to by pulling your legs closer to your center of mass. How do you make yourself rotate? You need to start with some rotation. Simple, right? Anyone should be able to do that. I guess this would actually be a front tuck, right? Well, the key here is that during the time you are in the air, your body needs to rotate 360°. I looked at Dwight Howard's jump and he has a change in center of mass around 1 meter. However, it isn't a world-setting record or anything. Looking at the vertical position data, it looks like the change in height for his center of mass is about 0.46 meters (18 inches). I guess the real question would be: what was the vertical change in height for his center of mass. This is pretty close to the expected value for the vertical acceleration of a free falling object - about -9.8 m/s 2 Now for some almost random questions. Here you can see the vertical acceleration of Simpson while in the flip is about -9.4 m/s 2. Ok, it looks like this turned out a little better. This is the horizontal (x-axis) motion of my guess for Simpson's center of mass (which I approximate as being around his waist). Oh, if you want to analyze a video like this with Tracker, let me suggest that you use calibration point pairs. For this one, the camera seems far enough away to not matter too much. Most football videos have some type of weird camera angle. This video isn't too bad as far as analysis goes. ![]() For this motion, let me just create a plot first. I am pretty sure that would count the same as a fall. You know, just to provide full coverage of Jerome Simpson. Nonetheless, I feel compelled to post a quick analysis of this flip. ![]() In my previous post, I blamed the Simpson-flop on Fujita's Jedi powers. ![]()
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