How Does Raising Arms or Leg Amputation Affect the Center of Mass?

[thegirlchild]

[SOLVED] center of mass

in which direction would the center of mass of the body migrate if the arms were raised overhead? what about if the person had a bilateral amputation of his legs?

 

[CompuChip]

How is the center of mass defined?

 

[thegirlchild]

the point in the exact center of an object's mass

 

[HallsofIvy]

Yes, now think what happens to the mass in both of those questions. These problems don't require specific calculation, just a general statement.

 

[Doc Al]

the point in the exact center of an object's mass

A helpful way to think of it might be as the average location of the object's mass. (Imagine the object being composed of a bunch of small pieces.) For something uniform, that "average" location would be right in the middle.

Think of a pile of bricks. It has some center of mass. Now move a few bricks to the right. What must happen to the average position of all the bricks and thus to the center of mass of the pile?

Apply that same thinking to your problem.

 

[thegirlchild]

it would go down if your arms are raise and go up for a bilateral amputation of the legs?

 

[yc90]

if u raise ur arm the upper part of ur body will have more mass hence the "center" of mass would be...

 

[thegirlchild]

higher

 

[Doc Al]

higher

Right. Just like moving some of the bricks in the pile to the right results in the center of mass moving to the right, raising part of your mass by lifting your arms results in a raising of your center of mass.

(Obviously if you raised your entire body--by stepping on a ladder--your center of mass must rise along with you. It's the same with raising your arms, only to a lesser extent.)