# What if the Earth suddenly stop revolving around its axis?

Discussion in 'Physics & Math' started by Saint, Sep 4, 2017.

1. ### DaveC426913Valued Senior Member

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Yup. Slower than many fighter jets. And they do not get thrown into outer space.

Note though that you don't need to achieve orbit to be thrown into space (at least temporarily).
It would be sufficient to reach a suborbital parabolic trajectory (the extreme lower end of the range you mentioned).

(This would not be as hard to do as one might think, because one is not being launched ballistically in stationary air. We would be thrown as one with all the air. Essentially, a 1000mph wind would carry us bodily off the planet.)

Last edited: Sep 5, 2017
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3. ### billvonValued Senior Member

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No, you would just feel like you had been launched out of a cannon at ~1000mph.

If the Earth and atmosphere stopped at the same time, then you'd likely break a few bones before hitting the ground at hundreds of miles an hour, killing you.

If the Earth stopped but the atmosphere kept moving, then you'd be fine for a half a second, until you fell and hit the Earth which would be moving 1000 mph beneath you.

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5. ### DaveC426913Valued Senior Member

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Not sure about the half second part. As I mentioned, this is not a normal situation (akin to the wind of a storm).

You will be carried along with the atmo at 1000mph - it is not a wind that is bounded to a discrete volume that you can fall out of. The whole atmo is carrying you.

(Naturally, it is no where near as simple as this. The atmo is in turmoil, and will smash you about, even as you might be falling.)

Look, imagine you are a spherical chicken of uniform density...

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7. ### billvonValued Senior Member

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Right, but it will not levitate you. Very quickly a few things would happen:

1) You'd contact the surface doing 1000mph relative to you.
2) Friction with the ground would start slowing the atmosphere to the speed of the ground.
3) You'd discover anything near you that is not exactly the level of your feet moving towards you at ~1000mph.

About the only people who'd survive are those who live VERY far north or south, people in airplanes, skydivers and BASE jumpers in flight.

8. ### DaveC426913Valued Senior Member

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At this point, I think we get in to the details of what any given part of a 10^18kg turbulent-flow mass of atmo would do. I suspect it will not be a scenario where simple ballistics will apply to objects caught in the gale, such that they simply drop in accordance with gravity, independent of their horizontal movement. It's likely objects would be carried up as much as down.

For example, depending on where they are, they might be in a mass that runs up against another mass which has been slowed/stopped by geography, resulting in massive deflection upwards.

Perhaps we can agree that we have no clear idea (short of simulations) what a 50 mile tall, horizontally unbounded mass of air, accelerating to 1000 mph, would do to at the 50kg object scale.

Well, except kill them. We probably wouldn't need the simulator to draw that conclusion.

Last edited: Sep 5, 2017
9. ### billvonValued Senior Member

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Instantaneously, that's exactly what would happen. You would fall as if someone just yanked the rug out from under you.

Beyond that first instant, of course, things become very complex, since the ground (from your perspective) is now traveling at 1000mph through still air with you.
No reason for them to be - any more than the air would carry you up right now.
Right - after a few moments, once the high speed ground starts to interact with the stationary air (and person.)

10. ### DaveC426913Valued Senior Member

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Hm. I guess when a strong, sudden gust blows across my deck, my papers don't fly in the air. They just skid across the table, laying completely flat? (After all, it's only gravity and a strictly horizontal wind flow) If I put up a 1mm barrier around my table's edge, my papers are impervious to gusts?

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11. ### timojinValued Senior Member

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Grow up, bring something constructive instead your fantasy

12. ### timojinValued Senior Member

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We will have a bib big tsunamy

13. ### BaldeeeValued Senior Member

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That might depend on numerous factors, but objects in the path of a flowing fluid will likely cause distortion, (eddies, vortices, vacuums etc) such that putting an object in the path might actually cause the papers to be more affected than if no object at all.

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14. ### XelorRegistered Senior Member

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As a practical matter, the Earth "suddenly [not] revolving around its axis" would produce the biggest wind storms, earthquakes and tidal waves imaginable.

What happens when one is in a car and the driver slams on the brakes? The car stops and everything in or on the car continues moving in the direction the car was going prior to stopping. That's what every single solid object on the Earth would do. Indeed, inasmuch as the Earth's crust rides above the mantle, I would be surprised if even mountains remain intact. I think what would happen is that brand new mountain ranges would get repeatedly created and destroyed in time periods shorter than that of humans' lifespan. The plates that form the Earth's crust would essentially behave like bumper cars until ebbed be the residual energy of the cessation of the Earth's rotation.

What about fluid matter? Put water in a baking dish/pan/turkey roaster. Hold the pan in both hands and gradually begin to spin around in a circle. Then stop suddenly and watch what the water does. That's what the water in the oceans, lakes, rivers, ponds, etc. will do if the Earth were to "suddenly stop revolving around its axis." I have no idea how big would be the worldwide tidal wave from such an event, but I suspect there's a way to calculate what it would be. I suspect that every drop of water in the oceans would, in successive miles-tall "tidal waves," for months sweep across the entirety of every landmass on the planet in much the same way that stirred fluid continues to swirl around until the energy that started it spinning dissipated. (In addition to water, the Earth's atmosphere being gaseous would behave much like water. Accordingly, at all levels of the atmosphere, it'd be insanely windy, 1000+ mph winds windy.)

We wear seat belts to attach ourselves to the car so that its rate of movement and ours are, as much as possible, are matched. We move about the Earth without any sort of attachment to it. The structures on Earth are attached, but not nearly strong enough to keep them stationary were the Earth's rotation about its axis to come to a screeching halt.

Who would survive such an event? People fortunate enough to be someone other than within Earth's atmosphere. Certain waterborne bacteria and very primitive life forms would probably survive.

15. ### billvonValued Senior Member

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They do fly in the air as the air accelerates them to its speed.

But if the air and your papers suddenly reached 100mph (as in this example) the papers would stay flat as they skidded off the table, because both the air and the papers were moving at the same speed. Once they were off your table, of course, it's hard to predict what would happen next.

16. ### billvonValued Senior Member

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The earth can't stop rotating instantaneously without some magic, so we are assuming that said magic affects the entire Earth (thus avoiding the earthquakes etc.)
Right. But what if you were in a car and the car's velocity (and everything in it) changed from 60mph to 0mph without decelerating? Nothing would go flying and the car would feel no ill effects. [/quote]

17. ### XelorRegistered Senior Member

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Truly, I am kicking myself for responding to the thread question because the matter was asked about and answered long ago and my thoughts add nothing of note to the discussion or to the analysis of what what would happen. In 1997, for example, Dr. Sten Odenwald addressed it at a level that is surely sufficient for this discussion: https://image.gsfc.nasa.gov/poetry/ask/q1168.html.

In the 17th century, Isaac Newton documented the laws of motion, which, as far as I know, have not been repealed.

The tone of Dr. Odenwald's remarks suggest that an instantaneous cessation of the the Earth's rotation is not impossible, but probabilistically is very near impossible.

Say what? The change in the car's velocity from 60 mph to 0 mph is nothing if not a deceleration.

18. ### DaveC426913Valued Senior Member

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This is a thought experiment. It is acceptable to set certain aspects of the scenario as simply "given" for the sake of the thought experiment. This is tricky to do; some elements can be idealized, some cannot.

I would want something more substantial than "tone" to convince me of this.

You're missing the point.

If a car and all its contents were instantly (and magically) moved from 60mpg to 0mpg then its contents would not go shooting forward.

i.e.: when the OP asks what would happen if the Earth suddenly stopped rotating (by some unspecified action), it raises the question about whether "the Earth" encompasses everything (and everyone) on it.

19. ### billvonValued Senior Member

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Of course. This is a gendanken - a thought experiment. It can't really happen. It is akin to the many thought experiments concerning relativity, most of them impossible to implement in the real world. They are nonetheless useful as a tool to understand physics.

20. ### sweetpeaValued Senior Member

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If your assuming the molten part of the core stops as well, then it seems the earth's magnetic field switches off.
http://www.geomag.nrcan.gc.ca/mag_fld/fld-en.php
Without the magnetic field it seems we lose the air molecules of the atmosphere:
http://www.askamathematician.com/2014/07/q-how-does-earths-magnetic-field-protect-us/

Last edited: Sep 6, 2017
21. ### DaveC426913Valued Senior Member

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I'm not sure the broken corpses remaining after the first hour will be too inconvenienced by an effect that surely requires a geological time frame.

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22. ### sweetpeaValued Senior Member

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So, we are all goners? No survivors to take advantage of the more favourable conditions of DNA mutation with all the high energy rays and particles?

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Last edited: Sep 6, 2017
23. ### DaveC426913Valued Senior Member

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OK, maybe some Northern Alaskans, a few Siberians and Inuit.