smhのようなどんな単語でも探してください。
 
1.
The point in a system of bodies or an extended body at which the mass of the system may be considered to be concentrated and at which external forces may be considered to be applied. Also called barycenter or centroid.
In general, an object with a lower center of mass is more stable. This explains why weebles wobble but they don't fall down.
razerによって 2006年12月21日(木)