Kinematics and Kinetics in Human Movement Practice Test

Center of mass is the balance point of the body's mass, found by averaging the positions of all its parts weighted by their masses. When you rearrange body segments, you relocate sizable chunks of mass to new locations. That change in mass distribution shifts the weighted average position, so the overall center of mass moves in space. The total body mass stays the same, but where that mass is concentrated changes with posture, so the center of mass is not fixed to any single spot like the skull and it doesn’t have to move only downward. For example, reaching the arms forward shifts the center of mass forward; lifting a weight overhead can raise and shift it upward; twisting can move it sideways. This shifting is a key reason balance depends on where the center of mass sits relative to the base of support.