How do mass, size, weight and density affect the centre of gravity?

[Physics Nic]

Hello everybody I am new here and I would like to ask a simple question about the centre of gravity and how it changes with mass, size , weight , density. etc.etc I would like to understand how this phenomenon happens and I have tried searching online to no avail so please help me understand how centre of gravity can change with the above

 

[Bystander]

how it changes with mass, size , weight , density.

These are easy, COM scales with the dimensions of the object.
"etc., etc.?" Those get a little tougher. Anything in particular? Geometry? Density gradient?

 

[Physics Nic]

Example, how does the center of mass change when weights of say 50 Newtons are applied to the undersides of a bus , I understand that the mass will affect (how easy it tips) during a turn but how does this come into play when calculating center of mass or center of Gravity whichever is easier ?

 

[Bystander]

http://en.wikipedia.org/wiki/Center_of_mass gives you the recipe. If you're asking where to pick an origin for the coordinate system, pick whatever is most useful for the system/problem you're examining.