What is the center of gravity?


What is the center of gravity and can it be moved? What would happen if it moved?

In: Physics

Gravity is an attractive force caused by anything that has mass. The more mass an object has, the stronger the gravitational force. The center of gravity is just the center of mass. If the center of gravity (mass) moves, the objects attracted to it would move with it, like we are moving with the earth.

You can’t fall through the Earth, but if you could use an X-Men power so that you’d fall through the ground, the center of gravity of the Earth is the point you’d fall to. It’s the “average” of all the gravitational force of an object.

When you do physics problems the center of gravity is useful because in most circumstances where you want to figure out gravitational force, you can ignore the object and just use the points that are the centers of gravity for each object. Instead of an irregular person shaped object to worry about, you focus on the single point that is their center of gravity.

You know how you can balance a pencil on your finger? You do that by finding the center of gravity, but it’s really a demonstration in only one plane. The center of gravity in a more irregular object, like a big rock, is basically the same concept as the pencil, but in all three dimensions. It’s basically the point of balance in an object, which the result of how mass is distributed in that object.

The “center of gravity” isn’t like a place, like the center of the solar system. Your question text makes it sound like you think it is.

You can think of it as the balancing point. If you set the object on your finger, or a pencil, and keep the center of gravity directly above where the support touches, it won’t tip over.

For a person, the center of gravity is in the middle of your abdomen and a bit lower than your belly button, assuming you’re standing naturally.

If you’re a person with moving parts, you can definitely move your center of gravity. The easy way is to change your posture – if you swing both arms off to the right (like a dab) your center of gravity will move right a little bit. If you wanted to permanently shift your center of gravity, you’d have to cut something off.

If you’re walking on a log or a tightrope, and you start to lose your balance, all that wild arm-waving and leg-throwing you instinctively do is trying to get your center of gravity back above your foot, where you need it to be.

Imagine pushing on something with your finger. Now imagine an line extending out from your fingertip. If that line passes through the center of gravity(CoG) of an object, the object will be pushed but will not rotate.

The center of gravity of a closed, isolated system cannot move. In other words, the effect from stuff outside the system is 0. Our solar system has a center of gravity. As seen from outside our solar system, it appears that everything orbits around that CoG.

There is a non-practical example where it may appear that the CoG has moved, but it has not. I’m not going to cover it unless asked.

It’s the V.

You can move it, but that would make the word difficult to read. grvaity, graivty, gvraity, etc.

the center of gravity of an object is not a physical property you can alter.

its a point in space within the object where you can “balance” its mass making it an ideal point to calculate force application from and be assured accurate results.

its a bit trickier in real life applications but the jist of it is simply that.

the way to “move” the center of gravity of object would be shifting its mass elsewhere, assuming the object is an immutable solid this isnt really practical or possible.

Of what? The center of gravity isn’t one single place. You can typically balance a pencil on your finger easily. The point where your finger is is the center of gravity of the pencil.

For more three dimensional objects you have to try and imagine having a four dimensional finger. Not easy, but you should get the general idea.