base411
June 16th, 2003, 12:57 AM
I have a friend who is an engineer who tells me that when you jump straight up on a trampoline with your hands towards the sky, bringing your knees to your chest will make you rotate foward. (Keep in mind he's not ever done a backflip - this is book knowledge) I practice back flips on the trampoline all the time and know this is false. His explanation is that the center of gravity changes foward - which is why you can't stand against a wall and pick up a chair - because you can't lean back. He's saying that to rotate backwards you have to lean backwards. My explanation is that the knees coming up creates the beginning of an arc that is going up and out, rotating around the hips. Leaning back creates an equal but opposite reaction that would make it harder to rotate backwards because your knees will want to go down. In addition, if you do get your knees up, it will be a 'whipping' backflip. Can anyone explain, in engineering language, the mechanics of a backflip as I've described? (All you gymnasts and divers) Why does bringing the knees up create the backflip?
tslobski
tslobski