What would happen if the Earth stopped rotating suddenly?

[Lookingglassman]

A buddy and I were arguing about this yesterday and I wanted to know what you all think. I said all humans would die because the earth's speed is fast and if it came to a sudden halt we would die, almost like a plane that is traveling at 500 mph suddenly coming to a sudden halt with no deceleration.

My buddy thinks we would all live for a while, but end up floating off the planet because there would be no gravity.

What would happen if all of a sudden the earth just stopped rotating? No slow deceleration, it just is turning one second and the next it has come to a dead stop.

 

[Mr. Laser Beam]

A buddy and I were arguing about this yesterday and I wanted to know what you all think. I said all humans would die because the earth's speed is fast and if it came to a sudden halt we would die, almost like a plane that is traveling at 500 mph suddenly coming to a sudden halt with no deceleration.

Yeah, that's pretty much it.

 

[David cgc]

Well, I suppose it depends on how much of the earth stops spinning. I mean, any magic that's powerful enough to cancel out the inertia of the entire planet would probably extend to the surface as well, so everything on it would be just as stopped as the rest of the planet.

Either way, gravity wouldn't be going anywhere. It relies exclusively on mass, and has nothing to do with rotation.

 

[backstept]

if anything gravity would appear to become stronger, because there wouldn't be any centripetal force making us lighter . . .
though it almost certainly wouldn't be perceptible to us, but maybe to very sensitive measuring equipment

 

[Bill Morris]

Remember that the Earth has a core of molten metal and an outer crust. It is conceivable for the crust to have a sudden change in orientation in relation to the core, where it would slip like an onion skin rather than continuing to match the rotation of the core. This probably happened several times in the distant past, not completely stopping as you suggest, but such that what part of the crust was above the magnetic north pole, for example, changed drastically and perhaps quite suddenly, resulting in massive death and destruction. But life went on. There is evidence of that, as well as shark's teeth in the Grand Canyon, elephant bones on the continental shelf of the U.S. east coast, etc.

 

[Gepard]

I imagine we'd all be flung off into space at tangents to the Earth's surface. Assuming some magic force which grabbed the planet and just stopped it cold, without affecting anything on the surface, of course.

 

[PlixTixiplik]

While "true polar wander" does happen sometimes, it's not a fast process (maximum 1 degree of movement / million years) and doesn't cause death and destruction. It is probably a shifting of the crust and mantle to get back into equilibrium with the core - at least that's what I gather from the paper. The paper was in Nature last week and it documented a couple of times of true polar wander in the last 320 million years, shown in this figure. The one between 250-220 million years ago seems to be a rotation around the Central Atlantic Magmatic Province, one of the largest volcanic eruptions ever, and was likely related to the start of the rise of that large mantle plume.

And most of what we can measure of the ancient movements of continents, including the things you listed (like shark teeth in the Grand Canyon) are almost entirely the result of normal relative plate movements during plate tectonics.

-MEC

 

[farmkid]

A buddy and I were arguing about this yesterday and I wanted to know what you all think. I said all humans would die because the earth's speed is fast and if it came to a sudden halt we would die, almost like a plane that is traveling at 500 mph suddenly coming to a sudden halt with no deceleration.

Many years ago my Father had to figure out something like this for an engineering class. The question had to do with the oceans if the earth slowed to a stop in a period of 1 hour. The solution came out to be that at the equator, the oceans would be moving about 900 mph. Yeah, major tsunami. The west coast of the continents and any islands would be flooded probably hundreds of miles inland. There would be massive destruction, with the distance from the equator determining the level of destruction. In the tropics, nothing would be left. At the poles, it may not even be noticeable.

 

[Timelord79 (he/him)]

A buddy and I were arguing about this yesterday and I wanted to know what you all think. I said all humans would die because the earth's speed is fast and if it came to a sudden halt we would die, almost like a plane that is traveling at 500 mph suddenly coming to a sudden halt with no deceleration.

Many years ago my Father had to figure out something like this for an engineering class. The question had to do with the oceans if the earth slowed to a stop in a period of 1 hour. The solution came out to be that at the equator, the oceans would be moving about 900 mph. Yeah, major tsunami. The west coast of the continents and any islands would be flooded probably hundreds of miles inland. There would be massive destruction, with the distance from the equator determining the level of destruction. In the tropics, nothing would be left. At the poles, it may not even be noticeable.

Oh my God! Someone should have told Superman before he... well you know!

 

[Delsaber]

Hopefully if something like this ever happens, it will bear as little resemblance to this as possible.

 

[All Seeing Eye]

If the Earth stopped spinning then wouldn't the Earths magnetic field suddenly disappear? isnt it the spin of the Earth and friction on the Iron core which creates the M-Field? wouldnt we be completely unprotected against interstellar radiation?

 

[anti-matter]

I think the gravity would stay the same...but it would result in the end of life as we know it...and yeah we'd all hit walls and whatever too...just like in a car that gets in an accident.

 

[Bill Morris]

If an asteroid were to strike the Earth from a trajectory nearly tangent to the line of latitude where it hit and from a direction roughly opposite the Earth's rotation yet not powerfully enough to puncture the crust, then some sudden slippage of the crust against the mantle could result, leaving the speed of rotation of just the crust diminished and causing tsunamis, etc. The rotation of the crust would then gradually regain its former rotation because of friction of the crust against the mantle.

That's case of sudden shift. The notion of sudden polar shift assumes a similar strike but from a more longitudinal direction.

 

[Verteron]

I imagine we'd all be flung off into space at tangents to the Earth's surface. Assuming some magic force which grabbed the planet and just stopped it cold, without affecting anything on the surface, of course.

No.

The Earth is rotating with a tangential velocity (at ground level) of about 1100mph.

If it (the rock) suddenly stopped rotating, animals, buildings, people and the atmosphere would still be moving at this speed. Essentially you and everything else would be tossed at 1.5 times the speed of sound in to the nearest building, or mountain.

You would not end up in space, because escape velocity for Earth is far far higher than this, at around 25000mph. So you'd fall back to Earth, and if you hadn't already slammed in to anything, the fall from several miles up in the air would undoubtedly kill you.

Additionally, the atmosphere and seas would be moving at this 1100mph speed too, so there'd be tsunamis thousands of feet tall and hurricanes of the kind we've never seen before.

Anything not anchored to the bedrock would be destroyed. Plants and trees would be torn from the ground. Topsoil would also be thrown in to the air.

It would undoubtedly be the end for multicellular life.

 

[Gepard]

I imagine we'd all be flung off into space at tangents to the Earth's surface. Assuming some magic force which grabbed the planet and just stopped it cold, without affecting anything on the surface, of course.

No.

The Earth is rotating with a tangential velocity (at ground level) of about 1100mph.

...

You would not end up in space, because escape velocity for Earth is far far higher than this, at around 25000mph. So you'd fall back to Earth, and if you hadn't already slammed in to anything, the fall from several miles up in the air would undoubtedly kill you.

Ah. Well, that was the gist of what I was trying to say anyhow. We'd all be flung...places. And stuff. Only you have math.

 

[Geoff]

The inherent problem with such a question is the fact that no known force could possibly cause the planetary rotation (including the crust, which "rides" atop the mantle) to come to an immediate standstill. So, in lieu of a complete reevaluation of the laws of physics, we're already assuming the intervention of some sort of "magical" force that we cannot begin to understand.

Therefore, any speculations about the consequences of such an intervention aren't particularly useful.

 

[Verteron]

The inherent problem with such a question is the fact that no known force could possibly cause the planetary rotation (including the crust, which "rides" atop the mantle) to come to an immediate standstill. So, in lieu of a complete reevaluation of the laws of physics, we're already assuming the intervention of some sort of "magical" force that we cannot begin to understand.

Therefore, any speculations about the consequences of such an intervention aren't particularly useful.

You're quite right. It's like asking what would happen if the Sun suddenly disappeared or gravity suddenly stopped working. Nevertheless, people do still ask these sorts of questions, and the Sun disappearing one is actually quite a useful thought experiment, as it leads us to the question of whether gravity travels at the speed of light (probably), or is infinitely fast (unlikely) and what implications that might have on the universe. So theoretically, the Earth would shoot off on a merry line in to space 8 minutes after the Sun went 'pop'. So these sorts of questions aren't always entirely useless.

One scenario I can think of that would stop (or greatly alter) the Earth's rotation would be a glancing blow by a fast-moving asteroid, although the forces required would probably leave us with far more problems than just a 1100mph fling to worry about, like fracturing a tectonic plate or three.

 

[Bill Morris]

I guess the scenario to imagine would be an asteroid entering the atmosphere over the Altantic and traveling nearly parallel to the ground over South America before being stopped by the Andes. If it carries enough energy to make the entire crust slip on the mantle enough to make the day a few minutes shorter, that's a big deal but not necessarily the end of all life on the planet. But to stop the rotation of the crust, leaving the mantle and core still rotating, would certainly rip the crust and expose the mantle, not that we'd notice if we were busy smashing into walls.

 

[Daedalus12]

A rough calculation using conservation of momentum reveals the requirement of a moon size object (in terms of mass) crashing down tangentially at 15 km/s.

 

[Lookingglassman]

All, Thanks for the great answers to my question. I am not talking about a magical force stopping it, it is just a hypothetical "what if". I know the Earth will not stop spinning suddenly, but me and my buddy were arguing over stupid stuff and this was one of the arguments.

I agree with those who say all life would die because it would go slamming into things. Thanks again for the great answers!