# Thread: Why does the Earth keep spinning?

1. I am no scientist and thoughts are my own, please be gentle!

For 4.5 Billion years our planet has been spinning, that is perpetual motion in my book.
What i cannot understand is, yes it's in frictionless space but it has gravitational forces pulling at it in the shape of our moon, causing Trillions of tons of water to be displaced every second, its also pulling at Earth's molten core. I thought this would be a huge damping effect.

To do this for 4.5 billion years with only a very small loss seems incredible.

The whole crux of my thoughts were
1. The Earth has been spinning for an awfully long time, thats a long time for anything to spin!
2. What factors are retarding the earths spin and can these be quantified?
3. Do the quantified factors add up to expected losses of spin over the Earths history.
4. Is there another force present assisting spin?

2.

3. There hasnt been a small lose 0.005 seconds per year per year (which means that 4.6 billion years ago the earth was almost spinning twice as fast as it is now) so it has been losing energy.

The spin of the earth is quite complicated (even the winds effect it to a degree) so im not sure that we know about all the things that have an effect on it.

4. Sorry river_rat, i know i'm new here and all but i've just done the basic maths with your quoted figures and the don't add up!
5 mS x 4.6Ga = 23Ms
23 Ms / 60 = 383333.3 Mins
38333.3 / 60 = 6388.8 Hours retardation in spin[/code]

5. told you i was new here, let me try that again

Sorry river_rat, i know i'm new here and all but i've just done the basic maths with your quoted figures and the don't add up!
5 mS x 4.6GYa = 23Ms
23 MS / 60 = 383333.3 Mins
38333.3 / 60 = 6388.8 Hours retardation in spin

assuming linear slowdown

6. Hehe, that is a problem. When figures don't add up bad things happen. If someone messed up, we could all believe that tomorrow Earth will stop spinning.

7. Originally Posted by tuggyman
told you i was new here, let me try that again

Sorry river_rat, i know i'm new here and all but i've just done the basic maths with your quoted figures and the don't add up!
5 mS x 4.6GYa = 23Ms
23 MS / 60 = 383333.3 Mins
38333.3 / 60 = 6388.8 Hours retardation in spin

assuming linear slowdown
Um how do you get that answer if i tell you the rate as 0.005 seconds per year per year?

The correct math is 0.005s * 4.6 billion years = 266 days/year (so we have lost 266 days in our year compared to then). So a year then had 631 days which means that the days were 57% of the length they are now.

8. By the fact you said "if i tell you the rate as 0.005 seconds per year per year" that's pretty linear to me"!

the reason i said "assuming linear slowdown" is due to other factors ie. moons orbit was closer having greater effect on tidal gravity etc

9. Originally Posted by tuggyman
By the fact you said "if i tell you the rate as 0.005 seconds per year per year" that's pretty linear to me"!

the reason i said "assuming linear slowdown" is due to other factors ie. moons orbit was closer having greater effect on tidal gravity etc
Do you agree that the numbers add up though?

10. sorry you are quite correct, i am new
i think im going to be an observer from now on, i realise my place in the great scale of things

11. Originally Posted by tuggyman
sorry you are quite correct, i am new
i think im going to be an observer from now on, i realise my place in the great scale of things
Dont observe - feel free to comment and if the need be there to rant. We all make silly mistakes here, and no one can claim to have all the answers.

12. i'm going to crawl under my metaphorical box!!

13. Isn't it right also, that as the earth slows the magnetic field around it will slowly weaken as well, something to do with the inner and outer core?

14. What the hell, lets go out in style

Is there another force present assisting spin?

Here a thought (just a thought)
The planet spins on it axis and produces a giant gyroscope. The Earth is also in a rotational orbit around the sun, could this angular movement of the orbit impart more rotational spin in our planet?

I suppose it a bit like the bicycle wheel experiment whilst sittng on a swivel chair but in reverse.

Im now holding my breath and closing one eye with both hands in my ears inside my metaphorical box!!

15. If you type 'why is the earth slowing down' into google you will get a whole list of sites explaining the reasons.

It seems it's mostly to do with the moon...

16. Thank you 'billco'.
Is that a polite way of not even having to answer my last question because its too riduculas.

Thats it i've blocked up the air holes, put on large sticker on my 'box' saying "pork products" and posted myself to Iraq.

17. tuggyman, stop being so pathetic. And don't reply to this with a "Oh, no, I'm so stupid I'm going to hide away at the bottom of the ocean." It's getting very tiresome. Contribute, ask questions, or just stop posting. It's entirely up to you.

The spinning of the Earth is not "perpetual motion" in the sense that you can't get any energy out of it without stopping the Earth moving. Perpetual Motion refers to machines that carry on moving although driving some other force which would ordinarily drain the energy - which is impossible of course.

Likewise, the gravitational force which keeps the Earth orbiting the Sun does not count as perpetual motion either. I can't remember the book that claimed that all science was wrong because something could move forever if you drilled a hole through the centre of the earth, but that was entirely based on the same misconception.

18. can anyone verify my statement or did i just imagine it, the one about as the earth slows the magnetic field weakens cause of something to do with the reaction of the inner and outer core

19. silas : Quote "It's getting very tiresome. Contribute, ask questions, or just stop posting."
I was not being pathetic the whiskey did not help!
It was a i think good atempt of being humorous, even now i've reread and sobered up, i laughed again!

Stop pontificating, and lighten up a bit, have drink, get a girl etc.

20. Originally Posted by captaincaveman
can anyone verify my statement or did i just imagine it, the one about as the earth slows the magnetic field weakens cause of something to do with the reaction of the inner and outer core
The Earth's magnetic field is generated by fluid motion in the outer, liquid, core. The conventional explanation for the field sees tt is a self exciting dynamo. The strength of the generated field is dependent, in part, on the rotation of the Earth. Logically, a reduction in the Earth's rotational speed would tend to reduce the magnitude of the magnetic field.

21. A\Q ME EARTH ROTATES DUE TO THE TORQUE EFFECT OF SUN

22. earth keeps rotating since it once started rotate and allways will rotate
There is no frame where earth will not rotate. It will slowdown but it wont stop

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