Because everything on the surface is pulled towards the centre (by gravity). The direction in which gravity pulls is called the local vertical.
If the Earth were a perfect sphere, then at any point, the vertical would be perpendicular to the surface (hence, everything appears normal over short distances).
How far must one look for things to be "not normal"?
The Verazzano Narrows Bridge (entrance to New York Harbour) has two very high support towers (they support the main cables which, themselves hold up the smaller cables holding up the roadway).
The towers are 4,260 feet apart. Each tower is 693 ft high. Each tower is perfectly vertical "at its spot" on Earth's surface.
The separation between the two tower's vertical axes is 1.6 inches more at the top than at the bottom.
They are both perfectly vertical, yet they are not parallel.
One nautical mile (6080 ft) is defined as the distance, on Earth's surface, covered by an angle of 1 minute at Earth's centre. Therefore, the angle between the two towers (if you continue the vertical axes to Earth's centre) is a little less than one minute.
2007-03-23 07:57:31
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answer #1
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answered by Raymond 7
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Here's the real answer.
There is no upside down EXCEPT relative to the earth's surface!
You are thinking of some outsider looking at the earth and some of the people are "upside down". What if that viewer were to turn 180 degrees vertically? Now the other people appear to be "upside down".
There is no such thing relative to the solar system. Down is towards the center of the earth, not "down" from the solar system where there is basically no gravitational effect on the human body whatsoever. So upside down simply means relative to the center of some mass, you are topwise.
If you could get off the earth, you would not fall "down" to some location "south" of the solar system. You would simply float.
2007-03-23 08:43:44
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answer #2
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answered by Anonymous
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This is because the Earth's gravity helps us define 'down' as the direction where objects fall, and up as the direction where objects fall from. And this is consistant throughout the globe. So everywhere we go, everything appears 'normal'. And also, the concave of the planet, is so subtle since Earth is a very big planet, that we can't actually see where it dips downwards with our eyes (unless we're in space or very high up in the sky). You may be upside down right now (in comparision to someone on the opposite end of the globe) and not know it.
2007-03-23 07:57:16
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answer #3
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answered by Shades of Green 2
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Gravity pulls you towards the centre of the Earth. So no matter where on Earth you are, your feet are always being pulled toward the ground.
Remember, when you're at Antarctica, you are also upside down, so the Earth looks normal to you. Since gravity always pulls you to the centre, the inclination of your head is always equal to the inclination of the surface. So it always appears to be horizontal.
2007-03-23 08:02:57
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answer #4
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answered by Anonymous
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Well, their's gravity on the Earth and not in space.
This means that in space there is no up and down, only where there is gravity. And it seems normal and flat on the surface because you're standing on such a insignificant perice of it that it seems flat. Actually, we're so small it's pretty darn close to flat.
2007-03-23 08:09:40
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answer #5
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answered by Anonymous
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There are two basic things that give people their sense of balance; The fluid in your inner ear and your eyes. Get those out of whack and motion sickness usually results. Keeping that in mind, no matter where you are on the globe, the force of gravity, and hence the force acting on your inner ear, is pointed toward the center of the earth. And, if you look up you see sky. So, the brain thinks it has the same orientation because there is no conflict between the two.
2007-03-23 07:56:59
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answer #6
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answered by nyquist1995 2
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Since Earth is having huge diameter and we are living on earth, when we see with our eye-sight which is having limitation to cover surface of earth,the curvature of earth seems flat and horizon as straight line.
If you see earth from high altitude from sky one can notice its curvature and will not seem in normal surface.
Magnetic pull keeps everything on earths surface,though all objects are going in stages of upside down or side ways while earth is moving .
2007-03-23 08:24:25
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answer #7
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answered by ashok p 1
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Gravity holds you to the surface and nothing pulls on you from the outside. The globe is so big that you can barely tell it is round. Gravity is equal everywhere you go on earth so it seems the same everywhere.
2007-03-23 07:54:24
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answer #8
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answered by Person 2
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funny how every one says gravity, but if gravity is powerful enough to attract all the bodies in the universe, how is it so easy to pick things up off the ground when the entire force of the earth is pulling on it. gravity seems to be both weak and strong. but anyway the circumference of the earth is so huge that the curvature is imperceptable to us. if you want to see it though, just watch a boat float over the horizon, it only disappears b/c the earth is round
2007-03-23 07:50:14
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answer #9
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answered by scauma 2
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i think of that what Mr. Bieber is calling isn't "Why does not the water fall off of the planet" yet quite, because of the fact the earth is around, it follows (intuitively) that "down" is in the direction of the earth, even in area. So, if I turn a cup "upside-down" it fairly is, precise-part in the direction of the earth, it would empty as all that water falls out. that's properly a reasonably insightful question, because of the fact it highlights some thing that i think of a large style of non-physics types are not attentive to: there is gravity in area. Very some distance from the earth, (or different gravitational bodies) that's so susceptible that that is negligible. yet for an area station in orbit, this gravitational pull is properly quite important. So why do not issues fall in area? Th answer is going back to those merry-flow-rounds you spot in play grounds. in case you get them spinning rapid sufficient, you sense pulled outward via the centrifugal tension (Physics majors do not shoot me right here. Centrifugal tension exists interior the spinning reference physique of the merry-flow-around) of your spinning. interior the comparable way, an merchandise in orbit feels the outward pull of the spinning as they spin around the earth. the area station is, via layout, going purely rapid sufficient to sense a centrifugal tension precisely equivalent and opposite to the gravitational pull of the earth so they cancel. it fairly is why the area station remains in orbit, instead of flying off like a shot-placed, or plummeting to the earth. yet that's additionally why water does not fall in area. The downward tension and the upward tension precisely stability one yet another.
2016-10-19 10:52:32
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answer #10
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answered by ? 4
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