# Gravity and centrifugal force

thespacemonkey
Posers and Puzzles 31 Oct '06 17:13
1. 31 Oct '06 17:13
I've wondered this for a long time; if the world stopped spinning would we feel the force of gravity more.

The reason I ask this is because I assume that the rotation of the Earth creates a fairly hefty amount of centrifugal force, so in our state at the moment are we feeling both gravity and centrifugal force, gravity being strong enough to both alieviate the feeling of centrifugal force and hold us down at the same time. So if the Earth stopped spinning would we feel an equivelient increase in gravity.

For what it's worth I wreckon we'd all get smushed, but that's based on nothing other than basic physics and intuition (which is so often proven wrong in science).

Dominic.
2. 31 Oct '06 17:32
Originally posted by thespacemonkey
I've wondered this for a long time; if the world stopped spinning would we feel the force of gravity more.

The reason I ask this is because I assume that the rotation of the Earth creates a fairly hefty amount of centrifugal force, so in our state at the moment are we feeling both gravity and centrifugal force, gravity being strong enough to both a ...[text shortened]... er than basic physics and intuition (which is so often proven wrong in science).

Dominic.
There would be a slight difference. Probably enough to measure, but you wouldn't notice it.

At the poles there's no centrifugal force. People have been to the poles and didn't feel any heavier. Colder, yes, but not heavier.

The calculation isn't all that difficult, if you want to do it. Acceleration towards the centre of the Earth, if you're on the equator, is w^2.r, where r is the radius (about 6000 km) and w is the angular velocity (2pi/24 hours).
3. sonhouse
Fast and Curious
01 Nov '06 15:03
Originally posted by mtthw
There would be a slight difference. Probably enough to measure, but you wouldn't notice it.

At the poles there's no centrifugal force. People have been to the poles and didn't feel any heavier. Colder, yes, but not heavier.

The calculation isn't all that difficult, if you want to do it. Acceleration towards the centre of the Earth, if you're on the ...[text shortened]... w^2.r, where r is the radius (about 6000 km) and w is the angular velocity (2pi/24 hours).
What he said.
4. TheMaster37
Kupikupopo!
01 Nov '06 16:58
If the world would stop spinning just like that, we would be launched straight into space.
5. 01 Nov '06 17:17
Originally posted by TheMaster37
If the world would stop spinning just like that, we would be launched straight into space.
No, we wouldn't. It would do a fair bit of damage, but we wouldn't be thrown out into space.
6. 02 Nov '06 01:44
Originally posted by TheMaster37
If the world would stop spinning just like that, we would be launched straight into space.
lol, not quite, there'd still be gravity to content with.
7. AThousandYoung
All My Soldiers...
02 Nov '06 12:22
Originally posted by mtthw
No, we wouldn't. It would do a fair bit of damage, but we wouldn't be thrown out into space.
Everything would get chucked eastward though.
8. leisurelysloth
Man of Steel
02 Nov '06 17:25
Originally posted by AThousandYoung
Everything would get chucked eastward though.
..including the oceans. Surf's up, dude!
9. 02 Nov '06 17:30
If the earth suddenly stopped, all the kinetic energy that the rotating earth earlier had would turn into heat energy. This energy would heat up the planet up to that extent that life as we know it no longer have a chance to survive.

Hundreds of centigrades, I believe, but a phycisist have to do the maths.
10. sonhouse
Fast and Curious
04 Nov '06 14:49
Originally posted by FabianFnas
If the earth suddenly stopped, all the kinetic energy that the rotating earth earlier had would turn into heat energy. This energy would heat up the planet up to that extent that life as we know it no longer have a chance to survive.

Hundreds of centigrades, I believe, but a phycisist have to do the maths.
Thats assuming a giant force or machine simply grabbed the entire surface area and stopped it there, then friction with the interior would start to heat things up. It would probably cause a lot of lava flow but the interior is already liquid so it would just redistribute the forces around inside and result in massive volcanic activity but the oceans would have to be held in place by the machine also if it already contacts the ground. At the poles there would be no motion since its already not spinning. That would be the safest place to be but all that volcanic activity would get you there later anyway.
11. 04 Nov '06 15:12
Originally posted by sonhouse
Thats assuming a giant force or machine simply grabbed the entire surface area and stopped it there, then friction with the interior would start to heat things up. It would probably cause a lot of lava flow but the interior is already liquid so it would just redistribute the forces around inside and result in massive volcanic activity but the oceans would h ...[text shortened]... would be the safest place to be but all that volcanic activity would get you there later anyway.
I don't just mean stopping the litsphere of the surface, I mean stopping the entire planet. Then there is no safe place on earth at all.
12. sonhouse
Fast and Curious
05 Nov '06 16:10
Originally posted by FabianFnas
I don't just mean stopping the litsphere of the surface, I mean stopping the entire planet. Then there is no safe place on earth at all.
Maybe, give a time frame. For instance, if you stopped it in one second, then you go from about 1600 Km/hr to zero in one second at the equator. That would subject loose objects to about 50 g's relative to the ground, which would knock the hell of of anyone.
13. 05 Nov '06 21:151 edit
The kinetic rotational energy of the Earth is ~10^29 Joules. If you released it all in one second, the Earth would have 10^29 We / (3.8*10^26 Ws) = ~250 times the power output of the Sun.
14. 06 Nov '06 00:521 edit
15. 06 Nov '06 07:33
Originally posted by thespacemonkey
If the entire planet of Earth stopped rotating in one sole second, but air and water still is free - I think every continent wolud be flooded by an enormous flood.

I think the wind is a minor problem. But, yes, I think we will have a *strong* wind for a while.

This has actually happened once if you read the bible. The sun stood still for 24 hours, meaning that the earth stopped suddenly from rotating and then started again. The effect of this disaster is not documented by the bible though.