Question

How much of the mass of an object behaves as if it is located at the Center of Mass?

Answer 1

In center of mass concept,, we assume an imaginary point and assume ALL the mass to be located at that imaginary point to make things simpler.

Let us take an example of a string lying vertically in air. If we are supposed to find its gravitational potential energy, we have to find the distance of every point of string from the ground. But if we apply center of mass concept, we select(by calculations ) an arbitrary point and assume ALL the mass to be present at that point and find the highet of that point to get potential energy. There are several other examples.