This is a very good (actually, deceptively good) question.
If you're standing on the equator, you're moving along with the earth at approximately 1,000 miles per hour. If you were being spun around on a merry-go-round at 1000 miles per hour (even in a vacuum with no wind resistance), you'd sure feel it.
Also (just to make things worse), the sun itself is rotating about the galactic center at a speed of over 10 million miles per day. Why can't we feel that?
As you probably suspect, it's because the radius of the circle that you're following is so large that the "force" (actually, the change in "angular momentum") that you feel is actually very small.
To use more big words - holding velocity constant, centripetal acceleration is inversely proportional to radius.
(Wikipedia is your friend.)
2006-10-27 07:27:52
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answer #1
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answered by Anonymous
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How fast is the earth spinning and why can't we feel it spin?
The circumference of (distance around) the earth is 2 x PI x radius, which turns out to be about 24,000 miles. Since the earth turns once per day (or 24 hours), that is 1,000 miles per hour! We don't feel that because everything else is moving with us and because the motion is very, very smooth. It's kind of like sitting in a car and reading a book or playing a game. If the car is going very smoothly, with no stops or bumps, and you don't look out the window, you wouldn't know you were moving. The only reason we know the earth is turning is because the sun and stars move across the sky.
2006-10-27 06:51:09
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answer #2
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answered by lee.sheehan 2
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The basic reason that we cannot easily, with our own senses, detect the rotation of the earth, is that the force of gravity downward is much greater than the outward centrifugal pseudoforce due to the rotation of the earth. Basically, this effect is swamped because it is so much smaller. However, it is possible to detect a measurable difference in the effective gravity on the surface of the earth at the equator and the poles due to the effect of the earth's rotation. Although the actual gravitational force is fixed, a small part of it is measurably 'cancelled out' by the centripital acceleration of the earth about its axis. On the other hand, we feel no backward or forward force due to the Earth's spin because it is spinning at a constant rate.
2006-10-27 06:43:29
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answer #3
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answered by locke9k 2
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It turns out that not only is the Earth spinning on its axis, but it is orbiting around the sun, which is in turn making its way around the galactic center at speeds of several hundreds of kilometers per second.
The reason we don't feel it can be explained by thinking of an airplane ride. Imagine we are in a perfect airplane. That is, an airplane that is flying at a constant velocity without slowing down, speeding up, turbulence or turning.
In this airplane, we are free to move about without noticing that the plane is moving. We can run, walk, play catch and do anything that we can do on the ground because we are moving at the same constant velocity as the airplane. In fact, if the windows were closed, there is no way we could tell whether we were flying along at this constant velocity or whether we were sitting motionless on the runway.
If, however, the pilot decides to speed up, slow down, or turn, the plane undergoes an acceleration and we can feel an inertial force.
Think of making a fast left turn in a car. You feel an inertial force pushing you to the right as a result of your frame or reference (in this case the car) undergoing an acceleration (the sharp left turn).
Like the plane, our solar system is moving very close to a constant velocity. So, just as in the plane, we can't feel that we are moving through space. Although the Earth is moving in a curved path around the sun, which means it is undergoing an acceleration, the inertial force is so small that we don't feel it.
We can however measure an inertial force caused by the earth's rotation. This force is called the Coreolis force and it plays an important role in our climate and weather planes.
2006-10-30 08:11:22
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answer #4
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answered by ^crash_&_burn^ 3
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All the answers above me are very much correct. If you know Newtons second law though, the physical answer as to why you can't feel it becomes obvious. At the surface of the Earth, you are travelling at the same velocity as the earth. However, F= ma implies that force is induced by acceleration (or appropriately, a change in velocity). Since the Earth rotates at a constant velocity, there is no angular acceleration and hence you do not feel an associated force.
2016-05-22 00:59:35
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answer #5
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answered by Anonymous
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Because we are moving at the same speed that the Earth is since we are on top of it. Our bodies can only sense acceleration (which is a change in velocity) because we sense motion with these little sacs in our inner ears that have fluid that sloshes around in them. It gets more complicated but that is not important.
If you imagine an open cup of water in a car, the only time that the water will spill is during an acceleration (like when the car is speeding up or changing direction). As long as you hold the cup and tilt it to keep it from spilling during that period you can put it back into the cupholder once you have reached the speed that you are going to maintain for a while and it won't spill a drop. Now the water in the cup is going at the same speed as the car.
Once the fluid in your inner ear is moving at the same speed as your body (when you have reached a constant speed) then it doesn't sense a change in the environment anymore and you can't tell that you are moving. As long as the Earth rotates at a constant speed, or changes that speed slowly enough that your inner ears can't sense it you can't tell that you are moving anymore.
2006-10-27 06:34:55
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answer #6
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answered by redrunner 2
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Hi,
You can't feel the Earth spinning because you, me, and everything else on the Earth, are moving with it.
If the Earth were to suddenly stop spinning, or if it were to suddenly speed up its rotation, believe me, YOU WOULD FEEL IT! Especially at the equator, where is spins at over 1000 miles per hour! You wouldn't feel it for long, though, because we would all die very quickly.
The earth is just over 24,000 miles around at the equator.
The earth has one day, or "Spins" one full cycle, every 24 hours.
So, at the equator the Earth is moving at just over 1000 miles per hour (Relatively speaking).
For perspective, most commercial jets travel at around 300-500 miles per hour.
2006-10-28 09:26:41
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answer #7
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answered by troydowning 5
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It's not spinning as fast as a Tilt-o-Whirl. The centripetal acceleration, which is what keeps you pressed against the wall in a Tilt-o-Whirl is a sizable fraction of the force of gravity.
The centripetal acceleration of the Earth's rotation is about 0.3% of the gravitation force, so it's negligible for normal actions.
2006-10-27 06:21:13
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answer #8
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answered by arbiter007 6
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Because we are spinning at the same speed as the world, we do not feel the movement. Of course, without gravity, we would be flicked off the surface and definitely would notice it then!
2006-10-27 15:27:38
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answer #9
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answered by Anonymous
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But we do feel it.
If you examine carefully the problem you'll understand that what we call our weight isn't a force that actually points towards the center of the earth. It's actually a centripetal force that maintains our cyclical movement on the surface of the earth. So we do feel it but we tend to ignore it (just like we ignore the feeling of our clothes since it's constant)!
2006-10-27 06:44:53
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answer #10
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answered by fanis t 2
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