How's my (physics) logic?

[ChrisGreaves]

Haida Gwaii man breaks world record for oldest male to do headstand
And here I quote: Ives believes being short may also make the move easier. “My centre of balance is a little lower than most of the big guys, so I think it might be a little easier for me,” he said.

I would have thought that a lower centre of balance meant that when you are upside down you ...

No! Hang about a bit ... your centre of gravity can no more be lower or higher than can the average of anything be greater or less.

I mean, no matter if my centre of gravity is in my head, it's still my centre of gravity, right?
(Exceedingly close to my "centre of mass")

(signed) of Bonavista.

[Jay Freedman]

Chris, your reasoning would be correct for a rigid object. The center of mass of a table, for example, doesn't change if you turn it upside down -- although it may be farther from or closer to the floor depending on whether or not the center of mass is located at the geometric center.

For a human body or any other flexible object, though, the location of the center of mass is quite changeable. When you stand straight with your arms hanging down from your shoulders, the center of mass may be on your center line and somewhere near waist height. If you raise one leg, your center of mass will shift upward; the same will happen if you raise both hands above your head, or if you sit in lotus position. Hold one arm out to the side, and the center of mass moves off your body's center line.

I'm not sure any of this supports the argument about shortness and headstands, but that's a different issue.

[GeoffW]

I suspect he's referring to the centre of gravity relative to the grounds rather than relative to a place in his body

If my centre of gravity was close to my head, I'd be a lot more stable upside down, when my head is close to the ground, than standing upright.

Or have I musinderstood?

[RonH]

As you age, your (or at least my) centre of gravity gradually moves south if you live in the north or north if you live in the south

[GeoffW]

As you age, your (or at least my) centre of gravity gradually moves south if you live in the north or north if you live in the south

So I'm Down Under, but I've lost over 20kg (45 lbs) in the last year. So I'm not quite sure in what direction my centre of gravity has moved.

[ChrisGreaves]

Chris, your reasoning would be correct for a rigid object. The centre of mass of a table, for example, doesn't change if you turn it upside down -- although it may be farther from or closer to the floor depending on whether or not the centre of mass is located at the geometric centre.

Thanks for this confirmation, Jay.
The original article was a light-hearted piece and I'm sure that the 82-year old was having a light-hearted interview, and is probably NOT related to my Physics Teacher of 1962-63,
I liked your table example, especially since a table has legs.

For a human body or any other flexible object, though, the location of the centre of mass is quite changeable.

This too now makes sense. In particular the position of my centre of gravity must change when I suck in my stomach etc. So during the transition from "standing on feet" to "standing on head" (or hands), but once that reversed position is reached, the centre of gravity must be a stable position once more.

In all of this I choose to ignore small perturbations. Presumably each beat of my heart changes the CoG as a wave of blood is swished through my brain.
Further, as an angular-momentum problem, gravitational effects on that part of the body further away from the centre of the earth would be slightly less than the effects on the parts adjacent to the surface of the earth. Calculable, but immeasurable.
Cheers, Chris

[HansV]

So I'm not quite sure in what direction my centre of gravity has moved.

Down the drain?

[ChrisGreaves]

So I'm not quite sure in what direction my centre of gravity has moved.

Down the drain?

Would that it would!
Cheers, Chris