Centre of gravity
Centre of gravity, in physics, an imaginary point in a body of matter where, for convenience in certain calculations, the total weight of the body may be thought to be concentrated. The concept is sometimes useful in designing static structures (e.g., buildings and bridges) or in predicting the behaviour of a moving body when it is acted on by gravity (Encyclopedia Britannica).
In a uniform gravitational field the centre of gravity is identical to the centre of mass, a term preferred by physicists. The two do not always coincide, however. For example, the Moon’s centre of mass is very close to its geometric centre (it is not exact because the Moon is not a perfect uniform sphere), but its centre of gravity is slightly displaced toward Earth because of the stronger gravitational force on the Moon’s near side.
The location of a body’s centre of gravity may coincide with the geometric centre of the body, especially in a symmetrically shaped object composed of homogeneous material. An asymmetrical object composed of a variety of materials with different masses, however, is likely to have a centre of gravity located at some distance from its geometric centre. In some cases, such as hollow bodies or irregularly shaped objects, the centre of gravity (or centre of mass) may occur in space at a point external to the physical material—e.g., in the centre of a tennis ball or between the legs of a chair.
The centre of gravity can be easily found through a simple, practical experiment. If an object is supported on a point, and it stays there without toppling over, the point at which the object is balanced is its centre of gravity. In this case, the total gravitational torque about this particular point is zero, which helps it balance and also helps us determine the object’s centre of gravity.
Encyclopedia Britannica. (1998 - 2023). Сentre of gravity, retrieved from: https://www.britannica.com/science/centre-of-gravity
Unacademy Study Material. (2024). Centre of Gravity, retrieved from: https://unacademy.com/content/jee/study-material/physics/centre-of-gravity/