Wednesday 20 March 2019

gravity - If the earth would stop spinning, what would happen?


What would happen if the earth would stop spinning? How much heavier would we be? I mean absolutely stop spinning. How much does the centrifugal force affect us?


If you give technical answers (please do), please explain them in laymen's terms, thanks.


Edit: I am asking what would be different if the earth were not spinning. Nevermind the part about it stopping.



Answer



The acceleration of an object spinning with angular velocity $\omega$ at a distance $r$ is given by:


$$ a = r\omega^2 $$



The angular velocity of the earth is 2$\pi$ radians per day or $7.3 \times 10^{-5}$ per second, and the Earth's radius is $6.378 \times 10^6$ metres, so the acceleration is 0.034 ms$^{-2}$ or 0.0034g. So as a person standing on the surface you wouldn't notice.


However the acceleration does affect the shape of the Earth. Rock is viscous and will flow in response to a force but it does so very slowly. As a result of the Earth's rotation it's radius is about 31km greater at the equator than at the poles. When the rotation stopped it would gradually settle back to a sphere, though it would take a million years or so.


The Milankovic cycles are at leastly partly due to the fact the Earth is not a perfect sphere, and these would stop or at least be changed when the Earth settled back to a sphere. Assuming you believe the Milankovic cycles cause ice ages, one effct of rotationg stopping would be no more ice ages. Having said that, stopping rotation would play havoc with the weather as you'd get no Coriolis force so no jet stream. Mind you, there'd be no hurricanes either.


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