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Newton's Laws in Ukemi |
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Newton's 1st Law- An object will remain at rest, and an object in motion continues in motion with constant velocity (that is, constant speed in a straight line)unless it experiences a net external force. |
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In this diagram the person being thown, from the third sketch on will be in motion and stay in motion until a he experiences a net external force. Gravity and the mat, after incountering these forces his motion will stop. In an ukemi roll the person being thrown would simply roll through the throw and use his own momentum to bring himself back to a standing position. |
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Newton's 2nd Law- The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the mass of the object (F=ma). |
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Just imaging using th F=ma law of Newtons in an instance such as this. If you fell (discounting the force of the thrower) with an acceleration due to gravity of -9.8m/s2 and a mass of 73kg (161 lbs.). When you hit the mat you would have force of 715.4N on your body. If you were to land on a small portion of your body (head, shoulder, etc.) there would be a great chance of injury. When you spread the force out along your entire body, like in ukemi, the force is the same, but distrubuted over a larger surfact which helps prevent injury. |
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Newton's 3rd Law- If two bodies interact, the magnitude of the force exerted on object 1 by object 2 is equal to the magnitude of the force simultaneously exerted on object 2 by object 1, and these two forces are opposite in direction. |
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The force of the mat is pushing upwards on the bottom man. He and the top man are pushing down. So what ever force they push down into the mat it will push the same and opposite back in their direction. If the bottom man were to have used his arm to support both of their weights it would surely have broken because of such a large force on a small part of his body. |
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Back to main page. |
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