Earth stops spinning, we fly into space?

[McCragge]

The other day I was watching a video of an atheist and a christian going at each other on a beach front debate. One of them mentions god stopping the sun for a day and the atheist says that would mean the earth would stop spinning and therefore we would all float off into space if that happened. Therefore it didn't happen, even if god wanted it too or something similar to that.

In any case, I was thinking about it. Does the rotation of the earth create the gravity we feel? I don't think so, I am, of course, no physics professor or learned scholar by any means, but I was under the assumption that mass determines how much gravity is felt. And if we look at the merry-go-round when it spins it pushes things away from the center due to centrifugal force. So, if the earth were to stop spinning, wouldn't we then feel the full effect of the earths gravity due to lack of centrifugal force? (granted it probably wouldn't be crushing gravity, but more then we are used to perhaps).

Is this correct? Or do we actually float of into space if the earth stopped spinning?

McCragge

 

[Zep]

Erm...no we would stay firmly attached. Until such time as we baked away in the sun or froze solid on the opposite side of the planet.

 

[nathan]

So, if the earth were to stop spinning, wouldn't we then feel the full effect of the earths gravity due to lack of centrifugal force? (granted it probably wouldn't be crushing gravity, but more then we are used to perhaps).

The Earth is an oblate spheroid because it is rotating (and sufficiently malleable). IIRC the equatorial radius is 14Km greater than the polar radius. If it stopped spinning, it would relax back to a sphere and your weight would be greater at the equator than now, and less at the poles than now. Your equatorial weight would be less than your current polar weight though.

 

[Jack by the hedge]

If the earth instantly, magically stopped spinning, then there would be the inconvenience that our own momentum would cause us all to fly off to the East at several hundred miles per hour (depending on our lattitude, of course). So it would be quite important to make sure the magic applies both to the planet and everything on it.

 

[arthwollipot]

Yes, we would all fly off, as we would still have momentum. We would accelerate in a straight line, so we would leave the surface, but the earth's gravity (which exists, as you say, due to its mass) would cause us to fall back down pretty quick.

From our perspective, everything would move very suddenly and very hard in a westerly direction, and would appear to drop away from us. But we would actually be following a ballistic trajectory around the world, and would land with a wet splat a few seconds after liftoff.

 

[Thabiguy]

Yes, we would all fly off, as we would still have momentum. We would accelerate in a straight line, so we would leave the surface, but the earth's gravity (which exists, as you say, due to its mass) would cause us to fall back down pretty quick.

Actually, strictly speaking, we wouldn't leave the surface. As we would be tossed eastward at less than orbital velocity, we would drop faster than the surface does due to Earth's curvature, so we would be falling down ever since the first moment. But hey, we could still be lifted off the ground if the terrain happens to be sloped, or if we bounce off the things we impact.

On the other hand, Jack is right. If one can use magic to stop the entire planet, it seems trivial to stop the surface stuff as well. Actually, it would be even more impressive if the spell was shaped so precisely as to stop all the Earth's mass but not the people on it.

 

[Lukraak_Sisser]

Don't forget the atmosphere either. If earth would stop spinning and it doesn't apply to the air rotating at the same speed the ensuing hurricane would pretty much wipe the surface clean.

 

[bokonon]

Don't forget the atmosphere either. If earth would stop spinning and it doesn't apply to the air rotating at the same speed the ensuing hurricane would pretty much wipe the surface clean.

H.G. Wells described his vision of it in "The Man Who Could Work Miracles":

You see when Mr. Fotheringay had arrested the rotation of the solid globe, he had made no stipulation concerning the trifling movables upon its surface. And the earth spins so fast that the surface at its equator is travelling at rather more than a thousand miles an hour, and in these latitudes at more than half that pace. So that the village, and Mr. Maydig, and Mr. Fotheringay, and everybody and everything had been jerked violently forward at about nine miles per second — that is to say, much more violently than if they had been fired out of a cannon. And every human being, every living creature, every house, and every tree — all the world as we know it — had been so jerked and smashed and utterly destroyed. That was all.

 

[MrQhuest]

I remember reading somewhere that the amount of energy required to stop the earth from spinning would liquefy the surface of the planet. I know we are talking magic though, just saying that flying off would not be the only thing to worry about.

MrQ

 

[Lothian]

In addition to any momentum problems the spinning is needed to create the magnetic field which surrounds earth and protects us from the solar wind. With out the magnetosphere the solar wind would destroy everything on earth…. or something.....

 

[Zep]

I was assuming that it was the biblical scenario - the Earth and everything on it stood still.

If someone stuck a stick in the Earth's spoke and jammed it at an instant stop but not everything on it, the result is very much like the others describe. I would add that the Earth's crust would likely slide with massive momentum, buckle titanically and release oceans of molten magma, etc. Into which we and all the contents of the Earth's surface would all be thrown sideways at colossal speed.

They should make it a Wii game!

 

[RationalVetMed]

The other day I was watching a video of an atheist and a christian going at each other on a beach front debate.

Aw, I thought this was going to be one of those old jokes...

One of them mentions god stopping the sun for a day and the atheist says that would mean the earth would stop spinning

Would the Earth stop spinning if the sun was stopped? If the sun just stopped spinning (not sure what you mean by 'stopped') wouldn't the planets continue orbiting as normal?

Yuri

 

[bokonon]

Would the Earth stop spinning if the sun was stopped? If the sun just stopped spinning (not sure what you mean by 'stopped') wouldn't the planets continue orbiting as normal?

The question is related to a story in the Bible, in which the sun supposedly stood still for a day so one tribe would have enough light to finish the job of slaughtering another tribe. Or something like that; I'm not going to look it up right now.

At the time it was written, it was probably thought, at least by the writer, that the sun moved around the earth, and thus "stopping the sun" would just mean halting this forward progress. With the modern understanding that the apparent motion is caused by the Earth's rotation, anyone who pretends to take the story seriously must deal with the possible effects of actually stopping the Earth's rotation. I don't see it as much of a problem; if you can really stop the rotation by magic, you can presumably deal with all the other inertia by magic too.

People who enjoy thinking about such hypotheticals might want to check out the Naked Science episode, ""When the Earth Stops Spinning", which considers the effects of a more gradual slowdown and stop.

 

[gambling_cruiser]

H.G. Wells described his vision of it in "The Man Who Could Work Miracles":

Nine miles per second equals 1000 mph?
Rotation speed at equator is about 463 meters per second (1519 feet per second).
Up to about 44 degrees of latitude we would move super/transsonic eastwards. Close to the poles you could survive until the melting of the earth surface gets you. Not to mention the 10++ richter scale earthquakes, the oceans splashing over, firestorms and other uncomfortable events not immediately obvious.
The god of the bible had to avoid all this unpleasant side effects, therefore he couldn't slaughter the enemies himself.
Sounds like he likes it complicated! Otherwise the enemies of his favorite tribe would have vanished in a blink and all would have impressed by this trick.
Maybe YHWH is at least as incompetent as Q in Star Trek.

 

[aggle-rithm]

If the earth instantly, magically stopped spinning, then there would be the inconvenience that our own momentum would cause us all to fly off to the East at several hundred miles per hour (depending on our lattitude, of course). So it would be quite important to make sure the magic applies both to the planet and everything on it.

That's what inertial dampeners are for. Presumably, God has watched Star Trek.

 

[bokonon]

Nine miles per second equals 1000 mph?

Yeah, I believe he should have written nine miles per minute. What a hack, huh?

 

[arthwollipot]

I remember reading somewhere that the amount of energy required to stop the earth from spinning would liquefy the surface of the planet. I know we are talking magic though, just saying that flying off would not be the only thing to worry about.

MrQ

Yeah, but as others have pointed out, this is divine magic we're talking about. God doesn't just stop the earth, He stops everyone and anything on it, including the atmosphere. God is omnipotent. He can do that ****.

 

[Skwinty]

God did not stop the earth, he turned the rest of the universe.

Sheesh people don't underestimate the powers of god.

 

[bokonon]

God did not stop the earth, he turned the rest of the universe.

Sheesh people don't underestimate the powers of god.

But... that would mean most of the universe was moving faster than the speed of light.

Awesome.

 

[Checkmite]

In addition to any momentum problems the spinning is needed to create the magnetic field which surrounds earth and protects us from the solar wind. With out the magnetosphere the solar wind would destroy everything on earth…. or something.....

No; it is the convection of the iron in the molten region of the core that generates the magnetic field. Stopping the rotation of the planet wouldn't eliminate the convection because the convection is caused by heat (from radioactive decay in the inner core), not the rotation.

The sudden motion disparity between the solid crust and mantle and the molten outer core would not need to be taken into account, because it is the entire mass of the Earth (including the core regions) whose rotation is being halted instantly as a unit.