center of gravity

Center of gravity

A fixed point in a material body through which the resultant force of gravitational attraction acts. The resultant of all forces or attractions produced by the Earth's gravity on a body constitutes its weight. This weight is considered to be concentrated at the center of gravity in mechanical studies of a rigid body. The location of the center of gravity for a body remains fixed in relation to the body regardless of the orientation of the body. If supported at its center of gravity, a body would remain balanced in its initial position. See Gravity, Resultant of forces

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

center of gravity

The point in a material body at which a single force, which is the resultant of all external forces on the body, may be considered to act. The center of gravity of a body in a uniform gravitational field coincides with the body's center of mass. A body does not possess a center of gravity, however, if the external forces are not equivalent to a single resultant force or if the resultant does not always act on the same point of the system. This situation occurs in a nonuniform gravitational field. The Moon has strictly no center of gravity although the resultant force of the Earth's gravitational attraction always passes within a few meters of the center of mass.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

center of gravity

[′sen·tər əv ′grav·əd·ē]

(mechanics)

A fixed point in a material body through which the resultant force of gravitational attraction acts.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

center of gravity, center of mass

A point within a body such that, if the whole mass of the body were concentrated there, the attraction of gravity would remain the same.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Center of Gravity

 

the geometric point through which the resultant of all gravitational forces acting on the particles of a body passes. The location of a body’s center of gravity is fixed relative to the body regardless of the body’s position in space.

It is possible for a body’s center of gravity not to coincide with any of the points of the body; a ring is an example of such a body. If a free body is suspended by a thread attached successively to different points of the body, the various directions of the thread will intersect at the body’s center of gravity. In a uniform gravitational field a body’s center of gravity coincides with its center of mass.

Suppose a body is divided into parts. If the weight p_k of each part and the coordinates x_k, y_k, z_k of each part’s center of gravity are known, then the coordinates of the center of gravity of the body as a whole can be found from the equations

In the case of a homogeneous body that has a center of symmetry—for example, a sphere, a cylinder, or a rectangular or round plate—the center of gravity is located at the center of symmetry.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.