What shape would the Earth appear to have if it were just covered by water

AI Thread Summary
The discussion explores how Earth's shape would appear if entirely covered by water, considering its non-uniform gravitational field due to its oblate spheroid shape. It highlights that gravity varies from the poles to the equator, affecting how water would distribute across the surface. The conversation emphasizes that if Earth were treated as a perfect sphere, the water depth would be uniform, but in reality, the shape would reflect the geoid, which accounts for gravitational variations. Participants note that while water contributes to Earth's overall gravity, its density is significantly lower than that of rock. Ultimately, modeling Earth as a spinning spheroid covered by water provides a practical approximation for understanding its shape.
Ahsan Khan
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Hello all,

I was going through study of gravitation of earth. The book teachs that gravity of Earth is more near poles than at equator as Earth is not perfect sphere rather radius of Earth is lesser near poles larger at equator. A thought came in my mind that if the water at level goes also through a varying gravity due to non-unformity of Earth spherical shape, I am also thinking that water itself is a contributing thing for overall gravity of Earth afterall water is also part of earth. And this whole complex system makes me not to figure out the real distribution of gravity at different points on earth' surface(including the surface covered by water). Will appreciate if anybody through light on this issue also I would like to know if I could take enough water so that if uniformly placed on Earth surface it could cover whole Earth If Earth were sphere. Keeping the fact that Earth is not perfect sphere and gravity is not uniform everywhere how would my water would spread on earth. Neglect effect of Earth's rotation and revolution around sun.

Regards
 
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ovais said:
I am also thinking that water itself is a contributing thing for overall gravity of Earth afterall water is also part of earth

yeah, but not much ... water density compared to rock is low
ovais said:
Will appreciate if anybody through light on this issue also I would like to know if I could take enough water so that if uniformly placed on Earth surface it could cover whole Earth If Earth were sphere

of course
and if the density was uniform through this spherical earth, then the depth of the water would also be uniform,
on a non-rotating/non-orbiting a sun and no moon, earth
 
So how would then it shape appear, same as that of solid surface seen now or a perfect sphere or what can be predicted about a modified shape?

Regards
 
ovais said:
So how would then it shape appear, same as that of solid surface seen now or a perfect sphere or what can be predicted about a modified shape?
Do you mean this?
https://en.wikipedia.org/wiki/Geoid
 
The free fall acceleration at sea level on Earth's surface varies from about 9.78 m/s2 at the equator to 9.83 m/s2 at the poles. About 2/3 of this difference is due to Earth's rotation, the remaining 1/3 due to the fact that Earth's radius is larger at the equator than at the poles.

Earth's surface is mostly covered with water, so modelling it as a spinning spheroid completely covered with water is a reasonable approximation for many purposes!
 
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