Lesson
Angular Kinetics - continued
CENTER of GRAVITY – its USE in MOTION and STABILITY
CENTER OF MASS = MASS CENTROID = CENTER OF GRAVITY
CM = A unique point around which the body’s mass is equally distributed in all
Directions
When a body is subjected to gravitational force, COM can be referred to as the COG.
CG = The point about which a body’s weight is equally balanced in all directions
OR
The point about which the sum or torques produced by the weights of the body
segments is equal to zero.
NOTE: EQUAL TORQUES on opposite sides of the axis of rotation NOT SAME AS
EQUAL WEIGHTS on opposite sides. (Equal Torques will balance out)
WHEN mass distribution WITHIN an object is not constant, the CG shifts in the
direction of greater mass. Every time an arm or leg moves, CG location shifts.
A BODY behaves MECHANICALLY as if ALL its MASS is CONCENTRATED at CG.