I see what you mean. Yeah, i'd still say it was inclination even though they could be sliding straight downhill leaning uphil. So, perhaps gravity should be added to the def.
Well the com is not a bodypart and maybe outside the body. Think of a boomerang. The com is in space, not in the object.
In general though, the com is where the most mass is. So let's say around the belly button. Simply banking, you're just letting your body fall inside the turn. Com will still be roughly belly button. Arms don't have much to do with it, but since they have mass, yes they will slightly influence where the com is.
But the banker didn't get inside the turn by using her arms! Stand near to a wall and fall into it withthe bodystraight. Do you use your arms for that? Well... in that case you might sice there's no turn force or slope. But you would have to push off a column or something to propel you.
It's not really important to know exactly where the com is, unless you're going to do calculations. Just knowing what it is and what affects the position of it is fine.
Look in the feet pullback thread on moguls. There's some gifs there that show com outside the body at times.
Yeah, I understand the COM is not a body part...it’s often outside the body. (I’ve taught physics ). The diagrams make sense to me; it’s the semantics that are confusing.