# If the Earth stopped spinning

## Main Question or Discussion Point

OK,

Newton's Universal Law of Gravitation tells me the magnitude of the force I feel here on the surface of the Earth. I know the direction is towards the center of the Earth.

I know g = G x Mass-of-Earth / r^2.

Neglecting all the other ramifications, if the Earth stopped spinning...

...would I still be able to walk around as before?

...would there be no difference in the gravity I experience (would I "weigh" the same?)?

Is there really no effect I would notice as a result of the absence of the my centripetal acceleration (since I'm no longer spinning around, because the Earth is no longer spinning around)?

What do you think?

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vanesch
Staff Emeritus
Gold Member
There is a small effect, which is usually calculated in a first course in geodesy. It changes the "effective equipotential" surface of the earth (the "ocean surface") from a sphere into an ellipsoid. But it is a tiny effect.

the centripetal acceleration caused by earth spin is so small that you can not sense any changes if the earth stopped spin. I have calculated it : a=2.1717e-5. It is opposite to the gravity so it is just 0.00022% of gravity acceleration.

D H
Staff Emeritus
the centripetal acceleration caused by earth spin is so small that you can not sense any changes if the earth stopped spin. I have calculated it : a=2.1717e-5. It is opposite to the gravity so it is just 0.00022% of gravity acceleration.
The value is considerably larger than that, but still quite a bit smaller than the acceleration due to gravity. The centripetal acceleration varies with latitude. At the equator, the value is $6378*10^3*(2\pi/86400)^2 \text{m/sec} = 0.0337 \text{m/sec}$.

The Earth's oceans would split into two polar oceans separated by a dry equatorial landmass if the Earth somehow stopped spinning but maintained its spheroidal shape. http://www.esri.com/news/arcuser/0703/geoid2of3.html discusses this "what if" scenario.

For a larger view, see
http://www.esri.com/news/arcuser/0703/graphics/geoid7_lg.jpg

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This is a good question. If the earth stopped spinning the winds would go north and south instead of east and west. Also I think the atmosphere would slowly leak away into space as earth's gravitiy would weaken. And if the earth stopped spinning one side of the planet would be in total darkness as the other would be in total sunlight which in time would be too hot enough for for anything to live there. The only shelter it would recieve is from the moon as it passes by the sun even then that wouldn't help much to the animals alive at the time.

vanesch
Staff Emeritus
Gold Member
Also I think the atmosphere would slowly leak away into space as earth's gravitiy would weaken.
Why would gravity "weaken" ?

Force of Gravity would not change.
The net force with which we are attracted towards earth's centre would increase*, if you are standing anywhere exept the poles(actual poles), a small centrifeugal force would now be absent which throws you out of earth, although very small but this force will now be absent.

centrifeugal force = 0 at poles.

well thats the gist.

*Actually there is no force that attracts us towards earth's centre, gravitation as a force does not exist.....for more info. study "general theory of relativity" by einstein .

Aside from the loss of a centrifugal force, we would also lose the coriolis force. (The force due to having the earth spin out from under you as you move). Of course, this is also quite negligible when compared to gravity but does play an important role in weather patterns.

I think if the earth stopped spinning, the weather would change completely of cource and not because the coriolis force only. The coriolis is nothing compared to the fact that one side was always day and the other was night.

if the earth stops spinning... would the magnetic field of it diminishes?

if the earth stops spinning... would the magnetic field of it diminishes?
No that would only be due to the fact that the earth's core stop spinning.

If the earth stops spinning, we would all fly into our houses and walls at 300 km/h, this would most likely kill everyone.

This is because we have an inertia. If you were to calculate the rate of rotation of the earth, we are actually "moving" at a very high speed while standing still on the surface of the earth. We do not feel it because relative to us, everything is moving at the same speed.

If the earth were to stop, we would continue travelling at this speed and suddenly things are hurtling towards us at ~300 km/h.

russ_watters
Mentor
Yes, though it is much faster than that for most people, more like 1000km/hr (latitude dependent).

It is true that we would crash into objects fixed to the earth at high speed. However structures such as houses would not be able to withstand such a sudden acceleration and would be ripped off foundations. Also, it is unlikely that the world would suddenly quit spinning. In the event that it did stop, it would probably slow down gradually instead of intantaneously, therefore frictional forces would be maintained and objects would not suddenly be airborne.