# Do large bodies of water (oceans) curve perfectly with the curvature of the Earth?

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Do large bodies of water (oceans) curve perfectly with the curvature of the Earth?

In: Physics

There are a few forces acting which mean no, not exactly.

The moon (and the sun to a lesser extent) make the ocean bulge at zero degrees and 180 degrees to the other body. This is the cause of the tides.

You also have the centrifugal effect near to the Earth’s equator, although the Earth itself does bulge about 40km at the waist.

And there is the effect of gravity which is non-uniform due to the large scale variations in density within the Earth.

It really depends on how accurate you want to be.

On the basic scale yes. Compare how smooth a billiard ball is, to the Earth, if shrink down to that same size. The Earth is actually smoother than that billiard ball even with mountains and ocean trenches.

But perfectly following the curvature? No. Tires alone mean there are two slight bulges of a few meters on either side of the Earth. But what’s a couple meters compared to a diameter of nearly 13,000,000 meters? Even my. Everest at 9,000 meters barely registers on that scale (only 0.06 %)