How to find the center of mass of the human?

Question

Ok let's say that we are talking about standing or lying person.

Answer 1

"The Human" is not a rigid body; its center of mass changes depending on how the arms and legs are positioned.  

Answer 2

You could do a reasonable approximation if you had a see-saw that you could balance so that it ended up - untouched - being level.

First you could have the person lie down on their baack on the see-saw.. You keep moving the person until you find the place where the see saw is balanced. Draw a vertical line, or pin a ribbon, along that vertical line directly above the pivot point. You could use a level to be sure you got a good vertical line.

Then have the person stand exactly over the pivot facing one the sides of the see-saw, and do the same balancing act, and draw another vertical line.  These lines will intersect at both the  front and rear of the person.

Then - and this will be difficult to be accurate - do the same when the person is facing the end of the see-saw,  The first two lines will intersect. To get the center actual, you will have to approximate the distance from the front or rear of the person. But you will get an idea of where it is.

This could be an interesting party game!