Centre of Mass
The unique spatial point representing the mean mass-weighted position of a physical system or extended rigid body.
Governing formula
R_cm = ∑ m_i r_i / ∑ m_i
SI unit
m
In depth
The net external force on an extended object accelerates its center of mass as if the system's entire mass were concentrated at that single point.
Examples in the real world
The parabolic trajectory of a thrown spinning wrench is traced perfectly by its center of mass.