The thought just occurred to me that someone would weigh more on either of the poles than they would on the equator!

I wonder what the difference would be?

I found a website on that once, I never visited again afterwards but it was interesting. The variations were very small though.

What really gets me is that when we stand upright, our heads are going through time at a slightly faster rate than our feet, so technically our heads are slightly older than our feet.

Unless you spend a lot of time laying down like me.

From the Nasa site I found the difference of the spheroid of the poles and the spheroid of the equator is 42km.

The Earth's gravity field is also determined by how the material that makes up the Earth is distributed throughout the Earth. Because gravity changes over the surface of the Earth, the weight of an object changes along with it. The more dense materials beneath your feat, the more pull, the more you seem to weigh.

http://en.wikipedia.org/wiki/Geoid

(February 2, 2009 at 3:40 pm)Tiberius Wrote: What really gets me is that when we stand upright, our heads are going through time at a slightly faster rate than our feet, so technically our heads are slightly older than our feet.

The strange thing is that, from the point of view of a neutral observer, the closer you are to a gravitational field, the slower time passes so indeed our feet would be younger.

However, our heads would also be travelling faster than our feet, and the faster something travels then the slower time passes..

Go figure..

And if you could sit at the centre of the Earth I guess you'd be effectively weightless.

Kyu

(February 3, 2009 at 6:22 am)Kyuuketsuki Wrote: And if you could sit at the centre of the Earth I guess you'd be effectively weightless.

Kyu

or just melted

(February 3, 2009 at 6:22 am)Kyuuketsuki Wrote: And if you could sit at the centre of the Earth I guess you'd be effectively weightless.

Kyu

I don't think you'd be weightless, Since gravity is attraction between objects with Mass, you would still be affected by the gravity of everything around you ... slightly different from being in space where weightlessness is caused by a kind of equilibrium between momentum and gravitational pull ... I think.

Sam

(February 6, 2009 at 9:32 am)Sam Wrote: I don't think you'd be weightless, Since gravity is attraction between objects with Mass, you would still be affected by the gravity of everything around you ... slightly different from being in space where weightlessness is caused by a kind of equilibrium between momentum and gravitational pull ... I think.

Sam

Your weight is just the NET force on you due to gravity. If you could get into the right position in the centre of the earth (and not burn to death :p ) you would indeed be weightless, since the parts of the earth of each side of you contribute equally and oppositely to the force acting on you.

Of course this neglects the gravitational attractions of everything else in the universe, but Newtonian gravity is an inverse square law, so those contributions are negligible

(February 6, 2009 at 9:32 am)Sam Wrote: I don't think you'd be weightless, Since gravity is attraction between objects with Mass, you would still be affected by the gravity of everything around you ...

But in such a way that you'd be pulled equally in all directions: you'd be weightless because there'd be no net force.

(February 6, 2009 at 9:32 am)Sam Wrote: slightly different from being in space where weightlessness is caused by a kind of equilibrium between momentum and gravitational pull ... I think.

Weightlessness in space is caused by a near absence of gravity: you're so far from the Earth (and any other large mass) that the net gravitational field at your position is near zero.

Momentum has nothing to do with it :p