COM Updates From Yesterday's Post

Image courtesy of wahmforlife.com

Two (possibly more) things I forgot to talk about yesterday regarding Center of Mass (COM):

1) The effects of lowering your COM on balance
2) COM vs. Center of Gravity (COG)


1) A lower Center of Mass allows for more motion over a given Base of Support (BOS) before falling over than a higher COM.

To illustrate this, pretend you have a two 10-foot poles, each with a base that is 8 feet by 8 feet with pole standing vertically in the center, so the edge of the base is 4 feet in any direction from each respective pole.  And let's pretend each pole is connected to the base via a system that allows it to move in any direction (minus levitating up or going down through the ground), like if you were to stick a barbell in a landmine or renegade or whatever you want to call the thing.

Anyways, let's say the COM of Pole1 is 10 feet off of the ground and the COM of Pole2 is 5 feet off the ground.

Can you see how if you were to lean Pole2 until its COM was at the very edge of its BOS, its COM would be 3 feet off of the ground? (5^2 - 4^2 = 3^2).  However, if you were to lean Pole1 until its COM was at the very edge of its BOS, its COM would be 9.165 feet off of the ground (10^2 - 4^2 = 9.165^2).

This means Pole1 would not be able to deviate as far from it's original vertical position before it's COM migrated outside of its BOS.

Image courtesy of ap-physics-b-project.wikispaces.com

If you aren't good with numbers or my example isn't making sense, think of those giant blow-up clown things with the weight on the bottom that you can kick and punch and it always pops right back up.  In that example, its COM is right above its BOS, so that thing can go almost all the way to the ground and still being able to return to it's original vertical position.

2) Center of Gravity (COG) refers to the interaction of gravity upon the COM of something.  According to Wikipedia (highly accredited resource, I know...), the "center of gravity is the point in a body around which the resultant torque due to gravity forces vanish" (source).  This means that, here on the surface of Earth, the COM and the COG are, for all intensive purposes, the same.

Okay cool that's what I have for today.  Per usual, it is highly unlikely that this post exhausted the possible discussions or talking points that could be had/made on these topics, so if there is something relevant that I completely left out or needs to be discussed in greater depth or detail, feel free to let me know below!

Your body.  Your training.

Want to use this arti­cle in your blog, newslet­ter, or other plat­form? You may, but be sure to include all of the bio­graph­i­cal infor­ma­tion found in the "About Me" section below!