Gravity Question?

Question

If the center of a sphere such as the Earth was not the center of gravity then what would be different?

Answer 1

Pretty much everything. In particular, unless constrained in some way, a rotating body *always* rotates around its center of mass (center of gravity)


Doug

Answer 2

First i'll tell you why this is impossible and then i will tell you what would happen

The Earth was formed under its own gravity.. Since gravity acts in all paths uniformly, when still hot gravity pulled all hot matter together uniformly creating a sphere..

Now for your question let's discuss Phobos, one of the 2 moons of mars which is not spherical

In order for an object in space to be round under gravity it has to have a mass of 3 x 10^21kg and larger

Phobos is not round because it didn't melt uniformely when it was being formed.

3/2 ( kT) = GMm/R

From this formula we can deduce the mass needed to cause a spherical object as given above finding the kinetic energy a particle must have to melt the matter involved..


From the formula above we can see what M is required to make T ( temperature) high enough to melt the rock of Phobos.Since M is not high enough particles hitting phobos did not have this amount of kinetic energy so gravity still acting uniformely kept the shape it had because no melting was taking place.. So gravity acts always at the center of any object regardless of shape

To answer your question... If we shifted the center of gravity there are a few possibilities of what would happen:

1. Everything would collapse as gravity is depended on mass..Assuming it would still hold the mass that causes the gravity pull.. If shifted it would still pull everything with the same force

2. If it wasn't the center of gravity it would not be a sphere.. it would create the sphere where the center would be again
3. Gravity would be strongest at near by matter

Basically gravity always acts from the center.. every mass has a center and therefore a center of gravity

Answer 3

First, Earth's center of gravity changes over time because the Earth's core is liquid iron and nickel, so that as the material gets slushed around (since the core is rotating and generating Earth's magnetic fields), the distribution of matter changes.

Second, when the Earth and the Moon was formed (this happened about 4 billion years ago when the two collided and both were destroyed and then re-created as two molten rockballs, one circling the other), the Earth was molten and its rotation caused a bulge to form around its equator. So when the Earth solidified back into rock, the bulge stayed in form, thus the distribution of material within the Earth is not perfectly spherical. This will also cause a difference between the geometric center and the "center of gravity" of Earth.

Answer 4

It depends on the distribution of mass inside the sphere. A sphere that had one half made of plastic and the other half made of gold would have its center of gravity somewhere over on the gold side rather than right in the middle. The Earth is fairly symmetrical inside, so the center of gravity would be quite close to the actual center, but not in precisely the same spot.

Answer 5

Then gravity would be greatest at whatever point on the sphere
was closest to the center of gravity...
If the iron core / center of gravity of the earth was not in the center,
say 5000 miles from one surface and 3000 miles from the opposite side, then gravity would be greatest at the surface 3000 miles from the core...

Answer 6

nothing really, the sun has a pretty irregular surface, yet it produces enough gravity to keep all 9 or 12 of the planets in orbit. There are other non spherical objects in space that produce gravity. I don't know how well defined black holes are, but they produce a lot of gravity. Theoretically though the object would be exerting gravity on all sides so it would attract matter from all sides, turning it into a somewhat spherical shape...

Answer 7

The Earth is really an ellipsoid and it spins as such .The Earth is not Uniform at it surface so the spinning is really a wabble.

a good explanation on this subject is described in The Ralph Rene wabble experiment in his book " The last Skeptic of science"This is the best scientific experimental evidence analysis I have seen so far in the world of Physics.

Answer 8

Gravity is inverserly proportional to the distance from the center of MASS - not from the center of VOLUME.

So if there is an off-center area of the planet that is disproportianately dense, that would make the CoG offcenter too.

Answer 9

It would be unbalanced, forcing a change in motion, and it would move. For example is the center of gravity of a tennis ball was on the surface of the ball it would roll.

Answer 10

nobody can stand or sit or do any thing errect