Why doesn't the water fall off  earth if it's round?
157120
This goes along with the question of why don't we fall off the earth if it is round. The answer is because gravity is holding us (and the water) down.
790097
Just look at the moon.  The moon has is made up of mantle rocks, just like the Earth's crust.  But there's no water, nor is there an atmosphere.  \n\nIt's actually not a fair question.  The Earth is in a wonderful position in that water is a liquid (too close it's a gas, too far it's ice).  Water is a very abundant substance - if a planet has an atmosphere, it has water.  The moon is too small and cannot hold an atmosphere, but there's no way the Earth would lose its atmosphere due to its size.  Therefore, there's really no way for the Earth to lose water.\n\nSo assuming the Earth COULD lose its atmosphere, you'd have a surface like the moon.
817654
Gravity...or if you mean why doesn't it come over the land...then that is because the land is higher then the sea, hence there is not enough water in the sea to raise it above the land.
789602
It's also true with water going down the drain. It goes the other way in the southern hemisphere, because of the earths rotation.
549724
It is downhill from start to mouth using sea level. However, there are rivers that do flow uphill at times. The continental divide is the reason for it. All water flows Easterly East of the continental divide. All water will flow Westerly West of the continental divide. I've been there and seen it, weird. \n\nAnother explanation would be the rotation of the earth. The water would be "pulled" toward the equator, where the largest mass of the earth's body would be.
223771
This is not true, but widely circulated as fact.\n\nI quote verbatim from snopes:\n\n"Because  \n\n   the Earth is a globe spinning on an invisible axis, a point at its equator will make a circuit of 25,000 miles in the space of a day, but any point not on the equator will make a shorter round trip; the closer that point is to either of the poles, the shorter its trip will be. Put another way, a pencil     at the equator travels 1,030 miles an hour, whereas another at Sarasota, Florida, moves at 930 miles per hour, and one at the North pole doesn't move at all. \n\n This apparent difference in speed results in the Coriolis force, an effect that imparts a twist to largish events happening away from the equator. Best known is its effect on air masses: as they move away from the equator, their speed (which matches that of where they started from) appears to be faster than that of the surface over which they are traveling. This sets them turning in a clockwise twist in the northern hemisphere and a counterclockwise twist in the southern. (Before you complain we have that backwards, please click here.)  Likewise, a cannonball fired due north will veer a teeny bit to the east, and one fired to the south will deflect ever so slightly to the west, something a skilled gunner would make an adjustment for. \n\n The twisting effect of the Coriolis force is real and does influence certain large things like the movement of air masses, but the effect is so small that it plays no role in determining the direction in which water rotates as it exits from a draining sink or toilet. The Coriolis effect produces a measurable effect over huge distances and long periods of time, neither of which applies to your bathroom. Toilets and sinks drain in the directions they do because of the way water is directed into them or pulled from them. If water enters in a swirling motion (as it does when a toilet is flushed, for example), the water will exit in that same swirling pattern; as well, most basins have irregular surfaces and are not perfectly level, factors which influence the direction in which water spirals down their drains. The configuration of taps and drains is responsible for the direction of spin given to water draining from sinks and bathtubs to a degree that overwhelms the slight influence of the Coriolis force. \n\n The belief that the Coriolis force influences the direction in which water drains from plumbing fixtures is widespread and has been repeated as fact in a number of venues, including popular television shows (such as world traveler Michael Palin's Pole to Pole) and even in textbooks.  We can only speculate on why people are so enamored of this snippet of misinformation, guessing that it has something to do with the desire to find some of the mysteries of science in the realm of the everyday. "
1123910
Only "large" celestial objects are round. Small ones, like asteroids, can be any shape.\n\nIt is the high gravity of large objects that makes them round. As they accumulated from smaller pieces, any piece that was out of round was pulled by gravity "downhill" so the overall shape of the body is round.
759329
There are 2 ways to think abut it.\n\nOne way is that the centrifugal force of the orbital motion balances the gravity of the Sun, so if the Earth is orbiting a little too slow, it falls toward the Sun. But as it falls, it speeds up which increases centrifugal force faster than the decreasing distance can increase the pull of gravity. The result is that the Earth ends up closer to the Sun but going too fast. The extra centrifugal force causes the Earth to fly away from the Sun, but as it does it slows down. And it slows faster than the rate at which gravity gets less with distance. The result is that Earth ends up farther from the Sun and going too slow, just where it started from. This repeats forever to make an elliptical orbit. The only way to get a circular orbit is for the Earth to have exactly the right speed, not even off by a millionth of a mile per hour from the right speed. That would never happen in nature, so all the orbits are more or less elliptical.\n\nThe other, more physically accurate way of looking at it is the Earth is always falling into the Sun, but the "sideways" orbital motion makes it miss the Sun to one side all the time. If it is going too slow, it doesn't quite miss the Sun enough and ends up falling a little closer. But as it falls, it speeds up. And from here on the explanation is the same as above, but it is the sideways motion allowing a continuous fall instead of a balance between gravity and centrifugal force. The reason this is more physically accurate is that centrifugal force isn't real. It is a virtual force, but that is confusing to most people not schooled in physics.
518623
when u swirl the water, if the object floating on it is not moving at the same speed, it would have a lower outward force. They r then pull by gravity towards the lower point... the middle of the swirling water. whichever thing slows down first, it will "drop" to the middle.\n\nI notice too that even if the thing does not float, like sugar, they r concentrated at the middle in the bottom. I think that's due to gravity too. When u swirl, water goes to the side and when the roundabout motion slows, water slowly falls back down to the middle. there's a net flow toward the middle and hence dragging the sugar to the middle.
974729
Gravity. Water doesn't seek its own level on the Space Station, it forms a ball-shaped blob.
644044
Why does it always spiral the same direction?\n\nIt *doesn't*.\n\nTry the experiment in your bathtub.  It can go either way.\n\nSome people mentioned the "coriolis effect", but for\nsomething as small as a bathtub, this effect is *tiny*.\n\nThe last references below describes experiments where (with\nvery careful controls) this effect was demonstrated, but\nfor most of our experiences, we're seeing other local\neffects (ie. residual currents in the water).  The\nexperimenters literally had to let the water sit for *days*\nin order to let the residual currents die down so that they\nwouldn't overwhelm the vanishingly small coriolis effect.\n\n[By the way, the coriolis effect is *not* vanishingly\nsmall for something *really big* -- like a weather\nsystem.  In that situation, there is a significant\ndifference in the speed (due to the earth's rotation)\nof the portion farthest from the equator vs. the \nportion closest to the equator.]
1003678
I think the world is round. Have you been outside of your room even? If the world was flat, you would be flooded, he he. Why are there mountains if the world is flat? Really you can't even answer my question? Try going to the library and actually do some research. Gotta go. Rock.
623455
The most basic stable physical shapes of revolving and rotating masses is spherical-note not a perfect sphere, because the shape tends to be flatted on the ends. Hence even the sun bulges along its equator and is flattened at the poles, as is the earth-this happens because of centrifugal forces caused due to rotation which throw material outwards, while gravity holds it and pulls it inwards.\n   \nThere must also be enough  mass too to generate enough gravitational force so that a spherical shape is formed. Astronomical bodies which are only a few kilometres across are irregularly shaped-eg. Ceres, an asteroid
945495
The idea that water drains counter clockwise in the northern hemisphere, and clockwise in the southern hemisphere is wrong. It is a popular misconception, and is based on something called the "coriolis force", which is kind of complicated to explain, but has to do with the spinning of the earth. It is true that the coriolis force would influence a liquid in the direction it drains, but the force is TINY compared to the other forces present in the liquid. The way water drains - whether clockwise or counter clockwise - is based mainly on the intial direction of the water in the container, not whether it is in the northern or southern hemisphere. So in short, at the equator, it will drain in either direction, depending on the initial direction! Hope this helps!
463058
Planets aren't directly formed from explosions and whatnot, they are formed from gravitational accumulation of mass in dust clouds. They are approximately round for the same reason anything that is approximately fluid that experiences a central force is round. Central forces have circular potential energy wells.\nConsider a cubic planet. A mass on the face of such a planet would be experiencing less force than a mass near a corner of such a planet (The corner has a greater amount of non-cancelling mass "behind" it. If you know the divergence theorem, this can be seen as well.). Since less force is exerted on points on the faces than points near the vertex, the vertex will slowly collapse if the mass is great enough, easily pushing the points on the faces outwards until an equilibrium is reached. This thought experiment works for any polyhedron, with the sphere being the limiting shape. Once the shape is approximately spherical, it is a well known proof that the force experienced by a particle outside the sphere will be the same as the force if the sphere was a point mass at the center of the central force, giving us back the circular potential energy map.
320933
Two reasons:\n\nPrimary = spinning + gravity = natural inclination of the material to slowly reach equilibrium. Anything that is not "round" gets pulled/shifted toward the center of gravity (the center of the Earth). The spinning helps this process over billions of years.\n\nSecondary = weather. Erosion constantly smoothing out "bumps" (mountains).\n\nIf this is the best answer, please vote it the best answer. Thanks!
554133
The water in the sea doesn't fall due to the gravitational force of the earth which sticks everything on the surface.