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Decomposition of Forces
The longer the rope, the easier it is to pull a heavy load because of the decomposition of forces. It is easier pull an opponent off balance by pulling the hand of the opponent's extended arm than it is to pull on the opponent's shoulder.
Time and Distance
The longer a force is applied to an object, the greater its final velocity. The greater the distance a force is applied to an object, the greater the time the force is applied, and the greater its final velocity. The final velocity desired in a strike depends on the situation. In point free-sparring, quickness is desired without a strong final force, while in a self-defense situation, a stronger final force may be desired. Therefore, in a self-defense situation, a technique may be cocked to provide a greater distance for the technique to travel, while in a free-sparring situation, the short, quick, less powerful technique is desired.
Moment of Force
A moment of force occurs when a force is applied anywhere except at the center of mass. It is what makes a fulcrum work. The product of the acting force and the distance between the axis and the line of action of the acting force is called the moment of force. For example, to lift a rock with a board, you slide one end of the board under the rock, place a small log under the board, and push down on the other end of the board. The closer you place the log to the rock, the greater the moment of force, and the easier it is to life the rock. To lift a standing opponent, pull the opponent's upper body forward with one arm, lean in and grab the opponent around the waist, and continue to pull the opponent over onto your shoulders so you may lift the opponent off the ground. The lower you grab the opponent below the waist, the greater the moment of force and the easier it will be to lift the opponent.