Q.Define center of gravity.

The center of gravity of a body is the single point through which the resultant of the gravitational forces acting on every individual particle of the body may be taken to act, for any orientation of the body. Each small mass element of a body experiences its own tiny downward gravitational pull; because any everyday object is minuscule compared to the size of the Earth, all of these countless individual pulls act as essentially parallel downward forces, and their combined resultant — the body's total weight — passes through exactly one fixed point relative to the body: its center of gravity.

Relation to center of mass. The center of gravity coincides exactly with the center of mass whenever the gravitational field is uniform across the entire body — an outstandingly good approximation for any object of everyday, laboratory, or even continental size on Earth's surface (the field only varies meaningfully across astronomical scales). Because of this near-universal coincidence in practice, the two terms are frequently used interchangeably, even though they are conceptually distinct: center of mass is about how mass is distributed, while center of gravity is about where the weight effectively acts.

Locating the center of gravity of an irregular lamina — two practical methods: …