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21.9.15

Motion

The Bouncing Ball
By Donny Shankle

Newton’s third law of motion tells us for every action there is an equal and opposite reaction. There are two forces at work within the law called an action force and a reaction force. The bar will move once the action force you apply to the floor is greater than the weight on the bar. The resulting reaction force is then transferred into the bar from the floor and it moves. The more powerful the force the faster the bar and correspondingly the weightlifter will move. In other words, you get what you put in.

Let us say for example, I bounce a rubber ball on the floor. If I were to throw the ball down using the power of my wrist it will bounce up. Now I decide to put my elbow into it and the ball bounces higher. Next time I decide to put my shoulder into it and the ball bounces really fast up and over my head. The more joints I am using and the faster I can control the lengthening and shortening of my muscles, the greater force I will apply into the ball. The floor will return the ball with the same effort I put in. The harder I throw it the faster it will change direction and the higher it will bounce. The only thing left now is to get aggressive and release the ball at the time it will go straight down.

The physics behind the bouncing ball analogy are the same physics behind the pull in weightlifting but in the opposite direction. Instead of throwing the ball down, you are moving up with the bar. The reaction from the floor will be equal to how fast the hips, knees and ankles act. Now combine the momentum you have created going up with moving under the bar at the right time. The “Finish” or final extension of your pull is like the ball hitting the floor. The faster it is the faster you will change direction.