Definition
The single point within an object at which all of its mass can be considered to be concentrated for the purposes of analyzing motion. It is the point about which the object would balance in any orientation, and the point through which an applied force produces straight-line (translational) motion with no rotation.
Plain English
The exact balance point of an object. If you could support the object at this one spot, it would stay balanced no matter how you turned it.
Context Anchor
Seen in weight-and-balance discussions, aircraft loading, and explanations of stability and control.
Derivation
From Latin centrum (middle point) and massa (a lump or quantity of matter). The term literally names the middle point of all the matter in an object.
Why Pilots Care
An incorrectly located center of mass changes handling qualities and can make the aircraft uncontrollable.
Analogy
Think of balancing a ruler on one finger. The spot where it balances is like its center of mass. An aircraft has a balance point too, but passengers, fuel, and baggage can move that point.
Grounding Statement
When weight is added, removed, or moved in the aircraft, the center of mass can shift.
Intuition Check
Do not assume Center Of Mass means the geometric middle of the airplane. It means the balance point of the aircraft’s actual loaded weight.
Example Sentence 1
Loading heavy bags in the aft baggage compartment shifts the center of mass rearward.
Example Sentence 2
Moving heavy cargo forward shifted the center of mass ahead of the forward limit.