Today I Heard My First . . . . .
ChatterBank1 min ago
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If it stopped, a day would last 6 months and night the same. The only energy the Earth creates is seizmic (volcanic,earthquakes etc) and this would go on regardless as it does not fully rely on the Earth spinning, mainly it is gravity drawing the materials in the earth towards the centre where due to extreme pressure heat up and become fluid and volatile. The Sun creates energy we rely on by creating the complex weather we have via the sea and land heating up and cooling down. The moon also influences the sea with it's gravitational pull. I imagine if the Earth stopped spinning, life would end due to the new weather system it creates, or perhaps most life, except species that can adapt such as bacteria and insects, and maybe evolution would start all over again.
There is another consequence. Our weather would change rapidly. At the moment there is a continual rebalancing between low and high pressure regions. The wind moves anti clockwise around a low pressure system due to geostrophic forces caused by the rotating world. In the absence of that rotation, the wind would move directly to the area of low pressure.
Thinking about it, because one area of the world would face the sun's rays for substantially longer than is possible now, you would get massive upward movement of air created by the ground heating up, which would suck in relatively cool air from around it. That air would continue to rise quickly, until it cooled enough to spill out and drop. I guess it would create hurricane like winds.
Kags... as for stopping quickly, that would take a collision of some sort. Remember that Earth is a body revolving in space and is subject to Newton's first law "equal and opposite force etc etc" If that happened we're all toast. Alternatively it would have slow slowly.
Netsquirrel... why would centrifugal force determine your weight??? Newton's second law in essence states that the gravitational force a planet exerts upon an object at the planet's surface is proportional to its mass and to the inverse of its radius squared. That would remain the same providing your mass remained the same.
.....and provided the Earth's radius stayed the same - which it wouldn't.
The lack of centrifugal force would cause a non-spinning Earth to lose its geoidal shape (flattened at the poles and bulging at the equator) causing a decrease in the equatorial radius. So, netsquirrel was on the right lines in that gravity would be altered, though I think there would be a slight increase in the weight of a body at the equator.
Wouldn't the Earth lose its delicate balance b/w graivity and the centripical force caused by it spinning? If there was no gravity and Earth was still spinning, everything on the planet would fly off into space. If the spinning ceased, but there was still gravity, would the force not "pull" us to the ground, virtually unable to move?
There would always be gravity on the Earth by virtue of its mass, irrespective of whether it is spinning or not.
Does gravity not "pull us to the ground" now, yet we can still move?
The only (tiny) changes to gravity that would occur would be where there has been a change in the Earth's radius as explained in the last-but-one post.
you misunderstand my point. Of course, there will always be gravity. It is, IN FACT, what keeps us planted on Earth. But it also is what counteracts the spinning of the Earth.
To answer the elementary question: "if the Earth is spinning, why do we not fly off the planet?" We would in fact, if it wasn't for gravity. So...switch the hypothetical question around and ask what would happen if the Earth were to stop spinning? (the original question by "dan no 1") Then gravity would play its effects, but minus the Earth's centrifugal spinning force of which gravity counteracts.
So if Earth stopped spinning, gravity would be that much moreso, with no spinning (outward) force to counteract. It's simply two forces at work (inward - outward = near equalibrium).
To answer the elementary question: "if the Earth is spinning, why do we not fly off the planet?" We would in fact, if it wasn't for gravity. So...switch the hypothetical question around and ask what would happen if the Earth were to stop spinning? (the original question by "dan no 1") Then gravity would play its effects, but minus the Earth's centrifugal spinning force of which gravity counteracts.
So if Earth stopped spinning, gravity would be that much moreso, with no spinning (outward) force to counteract. It's simply two forces at work (inward - outward = near equalibrium).
Apologies, chaotic1, I see what you mean now. You refer to the centripetal component.
Agreed, due to the rotation of the Earth, we experience an apparent outward force, but this is pretty minute compared with gravity itself.
The centripetal force (given by mV^2 / r ) on a body with a mass of, say, 1kg on the equatorial surface of a spinning Earth is 0.03373 Newtons
The force of gravity on the same 1kg body at the equatorial surface of the Earth is 9.780 N
So, a non-rotating Earth would result in an increase in gravity of only about 0.344%
Which is, I've just realised, the same figure NetSquirrel came up with about 6 posts and 24 hours ago. But is it an increase? Yes, it must be.
Jeez, I'm confused now - serves me right for doing geophysical calculations after a night in the pub.
yes, I see trilobite, you would weigh .344% more with the spinning absent...cause gravity's stronger due to there not being any centriPETAL force. So for a person to fly off the face of the Earth, you'd need much more centripetal force (faster spinning) or the same spinning, but a much smaller planet (less gravity). I'm still trying to imagine a way someone would crumble to the ground, using all their might to lift an arm or leg, due to too much gravity. Wait a second!!, what would happen if JUPITER stopped spinning, then we would...ahhh, forget it. You could imagine though!
GuavaHalf and deamo - It all depends on what you mean by "stops spinning". It could mean that the Earth stops spinning in relation to the Sun (in which case the Earth would have one hot side permanently facing the Sun and one cold side permanently facing outwards), or it could mean that the Earth stops spinning in relation to the background of the rest of the universe (in which case, one bit of the Earth would take six months to move from the Sun side to the dark side, and six months to mobve back again).
We might think of the Earth as "stopping spinning" in the latter sense (in which case GuavaHalf is right), but physically and cosmologically it would be far more likely for the Earth to stop spinning in the former sense (in which case deamo is right) and be locked in by tidal fixing (like the Moon is relative to the Earth, or Charon in relation to Pluto).
Sorry! i should have specified what i meant. i mean what would happen if the earth stopped ROTATING as it revolves around the sun.
reading all these different answers, i am still baffled, as i don't understand alot of the sceintific terminology!! BUT out of all the answers, WHO exactly is correct? is someone here a scientist????
