There are currently two explanations for the proximal-to-distal sequence, both based on the principle of conservation of angular momentum. Theory One ''external moment'' states that once the motion of the system begins, an angular momentum is developed in the system and the distal segment lags behind. As the proximal segment approaches maximum velocity, an external force opposes this motion, which negatively accelerates the proximal segment, allowing inertia to propel the distal segment forward (Ford, 1998; Marshal and Elliott, 1999). Theory Two '' internal moment'' contends that no external torque is applied to the system after the initial acceleration of the system takes place. The system with some mass, is said to move with a given angular velocity, thus having an angular momentum, which is conserved throughout the action (Putnam ,1983: Ford, 1998).
However, these theorys may not tell the full story and may infact only explain partial representation.
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