# Biomechanics - CoG and projectile motion

1. Dec 8, 2011

### set0447

Two basketball players jump for the ball. Both players have exactly the same mass and exactly the same body segment dimensions. Both players also take-off with exactly the same vertical and horizontal velocity of their center of gravity (CoG). Player A jumps up and reaches for the ball with both arms, while player B reaches for the ball with one arm (the other arm is down by her side). I need to use my knowledge of projectile motion and the factors that affect the location of the CoG to explain why the player that has one up arm up has an advantage and explain it in at least 1 page of writing.

initial kinetic energy = 1/2mv^2 where v equals the initial velocity of the player jumping up and m equals mass

This is what I have so far: The forces for both basketball players are the same. The height of CoG will be the same for both players. Potential energy is equal to the initial kinetic energy. The position of the CoG depends on the distribution of mass. When both arms are down, CoG is somewhere in the middle section of both basketball players.

2. Dec 8, 2011

### netgypsy

So what happens to the center of mass when one arm is raised and when both arms are raised? A very similar principle in used in high jumping and actually made a huge increase in the height jumpers could achieve when a new technique was mastered.