Centre of Gravity

I found out several things about the centre of gravity. Firstly, the centre of gravity is at the middle of things, in other words, at the very core of the object. Also, it is what causes things to balance themselves. The first time the concept of the centre of gravity was brought up was when Archimedes used this concept to explain the balance and lack of resulting moment when two objects are balanced in a specific way. Hence, if you have a sphere, its centre of gravit would be at the core. This is also why it is harder for spheres to balance: they have considerably smaller cores and less centre of gravity.

http://en.wikipedia.org/wiki/Center_of_mass